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The Vertical Farm: A Review of Developments and Implications for the Vertical City

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This paper discusses the emerging need for vertical farms by examining issues related to food security, urban population growth, farmland shortages, “food miles”, and associated greenhouse gas (GHG) emissions. Urban planners and agricultural leaders have argued that cities will need to produce food internally to respond to demand by increasing population and to avoid paralyzing congestion, harmful pollution, and unaffordable food prices. The paper examines urban agriculture as a solution to these problems by merging food production and consumption in one place, with the vertical farm being suitable for urban areas where available land is limited and expensive. Luckily, recent advances in greenhouse technologies such as hydroponics, aeroponics, and aquaponics have provided a promising future to the vertical farm concept. These high-tech systems represent a paradigm shift in farming and food production and offer suitable and efficient methods for city farming by minimizing maintenance and maximizing yield. Upon reviewing these technologies and examining project prototypes, we find that these efforts may plant the seeds for the realization of the vertical farm. The paper, however, closes by speculating about the consequences, advantages, and disadvantages of the vertical farm’s implementation. Economic feasibility, codes, regulations, and a lack of expertise remain major obstacles in the path to implementing the vertical farm.
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buildings
Review
The Vertical Farm: A Review of Developments and
Implications for the Vertical City
Kheir Al-Kodmany
Department of Urban Planning and Policy, College of Urban Planning and Public Affairs,
University of Illinois at Chicago, Chicago, IL 60607, USA; kheir@uic.edu
Received: 10 January 2018; Accepted: 1 February 2018; Published: 5 February 2018
Abstract:
This paper discusses the emerging need for vertical farms by examining issues related to
food security, urban population growth, farmland shortages, “food miles”, and associated greenhouse
gas (GHG) emissions. Urban planners and agricultural leaders have argued that cities will need to
produce food internally to respond to demand by increasing population and to avoid paralyzing
congestion, harmful pollution, and unaffordable food prices. The paper examines urban agriculture
as a solution to these problems by merging food production and consumption in one place, with the
vertical farm being suitable for urban areas where available land is limited and expensive. Luckily,
recent advances in greenhouse technologies such as hydroponics, aeroponics, and aquaponics
have provided a promising future to the vertical farm concept. These high-tech systems represent
a paradigm shift in farming and food production and offer suitable and efficient methods for city
farming by minimizing maintenance and maximizing yield. Upon reviewing these technologies and
examining project prototypes, we find that these efforts may plant the seeds for the realization of
the vertical farm. The paper, however, closes by speculating about the consequences, advantages,
and disadvantages of the vertical farm’s implementation. Economic feasibility, codes, regulations,
and a lack of expertise remain major obstacles in the path to implementing the vertical farm.
Keywords:
advanced cultivation methods; innovative technologies; efficient food production; urban
population increase; sustainability
1. Introduction
1.1. Background
This research stems from a larger research project that examined vertical density applications to
the 21st Century City [
1
3
]. As cities try to cope with rapid population growth—adding 2.5 billion
dwellers by 2050—and grapple with destructive sprawl, politicians, planners and architects have
become increasingly interested in the vertical city paradigm. Unfortunately, cities all over the world
are grossly unprepared for embracing vertical density, because it may aggravate multidimensional
sustainability challenges resulting in a “vertical sprawl” that could have worse consequences than
“horizontal” sprawl. One key problem of future cities will be transporting large amount of food to
serve dense population, and the vertical farm model offers a potential solution to this problem [15].
1.2. Goals and Scope of the Study
As urban population continues to grow and as arable land is diminishing rapidly across the
globe, a fundamental change in food production is needed [
4
7
]. In particular, building-based
urban agriculture is increasingly needed in dense urban environments and a review of current
cultivation techniques and projects would likely to contribute positively to academic discussions [
6
10
].
This is particularly important since vertical farming engages multiple disciplines of natural sciences,
Buildings 2018,8, 24; doi:10.3390/buildings8020024 www.mdpi.com/journal/buildings
Buildings 2018,8, 24 2 of 36
architecture, and engineering and affects both people and the environment [
9
11
]. This paper attempts
to answer the following questions:
What is a vertical farm?
What are the driving forces for building it?
What are the involved high-tech farming methods?
What are the salient project examples on vertical farming?
What are the implications for the vertical city?
1.3. Methods
Currently, we witness a growing body of research on vertical farming. Studies and updates on
the topic come in multiple forms including academic papers, professional reports, news articles, blogs,
and websites, as demonstrated in this paper references. This paper pieces together these materials in
attempt to answer the above questions. It examines a wide-range of literatures related to agronomy,
urban agriculture, vertical farming, and rooftop farming. It also reviews involved technologies, current
cultivation techniques, business models, and analyzes research projects.
This study evolved from anecdotal observations to systematic examination of involved
technologies, actual and visionary projects of vertical farming. In the preliminary stage, surfing
the Internet (website, blogs, movie clips) excited and fueled the research by informing about recent
projects that utilize advanced technology. This sparked systematic examination of generic (secondary)
and specialized (primary) literatures on vertical farming by using various online search engines and
databases including Scopus, ProQuest, and Google Scholar. Researchers collected over 100 sources.
These sources comprised 42% peer-reviewed academic journal articles, 28% books and book chapters,
6% theses, 9% conference papers, and 15% websites. Most of the reviewed literature is relatively recent,
dating 2010–2017. The reviewed projects come mainly from North America, Europe, and Asia.
Overall, this study adopts a qualitative informative approach. The paper gathers complex
technical information and makes them accessible to the non-specialists. Collectively, by reviewing,
organizing, and collating information of various sources, the paper hopes to provide a better
understanding of the theory and practice of vertical farming.
1.4. What Is a Vertical Farm?
Vertical farming seeks to ensure the sustainability of our cities proactively by addressing food
security to the world’s ever-increasing urban population [
4
8
]. In principle, it is a simple concept;
farm up rather than out [
8
10
]. The body of literature on the subject distinguishes between three
types of vertical farming [
9
11
]. The first type refers to the construction of tall structures with several
levels of growing beds, often lined with artificial lights. This often modestly sized urban farm has
been springing up around the world. Many cities have implemented this model in new and old
buildings, including warehouses that owners repurposed for agricultural activities [
8
]. The second
type of vertical farming takes place on the rooftops of old and new buildings, atop commercial and
residential structures as well as on restaurants and grocery stores [
9
,
10
]. The third type of vertical farm
is that of the visionary, multi-story building. In the past decade, we have seen an increasing number
of serious visionary proposals of this type. However, none has been built. It is important, however,
to note the connection between these three types, the success of modestly sized vertical farm projects
and the maturation of their technologies will likely pave the way for the skyscraper farm [9].
Environmentalists, urban farmers, architects, agronomists, and public health experts, among
others, have been joining this mini revolution as they partner to work out a way to salvage a food-scarce,
ultra-urbanized future. A wide number of technology experts have converged on the concept of vertical
farming, advancing the fields of robotics, aeroponics, aquaponics, and hydroponics. Nonprofits
organizations, aiming to promote environmentalism and local economic prosperity, have been backing
the vertical farm concept. Similarly, for-profit ventures that seek to meet the demand for local
Buildings 2018,8, 24 3 of 36
produce have supported this concept. Further, governments looking for ways to boost domestic
food security have been funding these endeavors. Numerous countries including Korea, Japan, China,
Germany, the United Arab Emirates, China, France, India, Sweden, Singapore, and the United States,
have convened to discuss vertical farming. They have repeatedly endorsed the concept as integral to
the long-term sustainability of their cities [9].
The idea of vertical farming is not entirely new. Examples of it can be found dating back to the
ancient era in the Hanging Gardens of Babylon, one of Philon’s Seven Wonders of the Ancient World,
built around 600 BC. In 1915, Gilbert Ellis Bailey coined the term “vertical farming” and wrote a book
titled “Vertical Farming”. He argued that farming hydroponically in a controlled vertical environment
would provide economic and environmental benefits. In the early 1930s, William Frederick Gericke
pioneered hydroponics at the University of California at Berkley. In the 1980s, Åke Olsson, a Swedish
ecological farmer, also proposed vertical farming as a means for producing vegetables in cities. He is
known for having invented a spiral-shaped rail system for growing plants [
4
9
]. Around the turn of
the century, Dickson Despommier, an American ecologist, and professor of public health, passionately
revived the concept of vertical farming. He described the vertical farm as “the mass cultivation of
plant and animal life for commercial purposes in skyscrapers. Using advanced greenhouse technology
such as hydroponics and aeroponics, the vertical farm could theoretically produce fish, poultry, fruit,
and vegetables” [
7
] (p. 15). The vertical farm is considered to promote sustainable agricultural practices
more than that by conventional farming, which refers to large scale, outdoor agriculture that embraces
systems that engage heavy irrigation, intensive tillage and excessive use of fertilizers, pesticides,
and herbicides [5] (p. 16).
1.5. Why Vertical Farms?
1.5.1. Food Security
Food security has become an increasingly important issue. Demographers anticipate that urban
population will dramatically increase in the coming decades. At the same time, land specialists (e.g.,
agronomists, ecologists, and geologists) warn of rising shortages of farmland [
4
6
]. For these reasons,
food demand could exponentially surpass supply, leading to global famine. The United Nation (UN)
estimates that the world’s population will increase by 40%, exceeding 9 billion people by the year
2050 [
12
]. The UN also projects that 80% of the world’s population will reside in cities by this time.
Further, it predicts that by 2050 we will need 70% more food to meet the demands of 3 billion more
inhabitants worldwide [
12
]. Food prices have already skyrocketed in the past decades, and farmers
predict that prices will increase further as oil costs increase and water, energy, and agricultural resources
diminish [
7
10
]. The sprawling fringes of suburban development continue to eat up more and more
farmland. On the other hand, urban agriculture has been facing problems due to land scarcity and high
costs. We desperately need transformative solutions to combat this immense global challenge [811].
The logic of vertical farming is simple: produce more food on less land [
10
,
11
]. The same
rationale that we use to stack homes and offices in limited and expensive land, such as in Hong Kong
or Manhattan, can apply to farming. Proponents of the vertical farm claim that it would create
compact and self-sufficient ecosystems that cover multiple functions, from food production to
waste management. Vertical farming could enable food production in an efficient and sustainable
manner, save water and energy, enhance the economy, reduce pollution, provide new employment
opportunities, restore ecosystems, and provide access to healthy food. In a controlled environment,
crops will be less subject to the vagaries of climate, infestation, the nutrient cycle, crop rotation, polluted
water runoff, pesticides, and dust [
12
]. As such, indoor farming could possibly offer a healthier
environment to grow food [
5
,
13
]. Since indoor farming operates year-round and is independent of
weather conditions, it could also provide greater yields and perpetual income [
14
]. Furthermore, indoor
farming provides a low-impact system that can significantly reduce travel costs, as well as reduce
GHG emissions, by cutting down on travel distances between distant farms and local market [
13
,
15
].
Buildings 2018,8, 24 4 of 36
Also, vertical farming could ignite local economies by providing much needed “green collar” jobs to
urban areas [5,13].
Importantly, vertical farms could help in addressing the problem of farmland shortages [
4
,
5
,
7
].
According to the United Nations’ Food and Agriculture Organization, there was 0.42 ha (1 ac) of
arable land per person on earth in 1961. By 2002, because of population growth and urbanization,
that number has dropped by nearly half, to 0.23 ha (0.5 ac) [
5
]. In 2011, the United Nations completed
a global assessment of the planet’s land resources, determining that a quarter of all arable land is highly
degraded. Further, since 1960, one million farmers in the United States have gave up farming [
5
19
].
Today, the country suffers from “23 million food deserts, defined by the U.S. Department of Agriculture
(USDA) as urban neighborhoods and rural towns without ready access to fresh, healthy, and affordable
food” [
20
] (p. 32). Dickson Despommier explains that current agricultural supply will soon become
largely inadequate. That is, on average, every human being needs 1500 calories daily, and in order to
meet such demand, we will need to add to existing agricultural land an area as big as Brazil by 2050 [
7
].
1.5.2. Climate Change
Climate change has contributed to the decrease of arable land. Through flooding, hurricane,
storms, and drought, valuable agricultural land has been decreased drastically, thereby damaging
the world economy [
7
,
11
,
12
,
18
]. For example, due to an extended drought in 2011, the United States
lost a grain crop assessed at $110 billion [
11
,
19
,
20
]. Scientists predict that climate change and the
adverse weather conditions it brings will continue to happen at an increasing rate. These events
will lead to the despoliation of large tracts of arable land, rendering them useless for farming. It is
common for governments to subsidize traditional farming heavily through mechanisms such as
crop insurance from natural causes [
6
,
21
,
22
]. Furthermore, traditional farming requires substantial
quantities of fossil fuels to carry out agricultural activities (e.g., plowing, applying fertilizers, seeding,
weeding, and harvesting), which amounts to over 20% of all gasoline and diesel fuel consumption in
the United States. We need to understand that “food miles” refers to the distance crops travel to reach
centralized urban populations. On average, food travels 1500 miles from the farm field to the dinner
table [
8
,
15
]. In special circumstances—cold weather, for example—food miles can rise drastically as
stores, restaurants, and hospitals fly produce in from overseas to meet demands. On a regular basis,
over 90% of the food in major U.S. cities is shipped from outside. A 2008 study at Carnegie Mellon
concluded that food delivery is responsible for 0.4 tons of carbon dioxide emissions per household
per year [
23
,
24
]. This is especially important given the increasing distance between farms and cities
from global urbanization. Sadly, the resulting greenhouse gas emissions from food transport and
agricultural activities have contributed to climate change (Figure 1).
1.5.3. Urban Density
Vertical farming offers advantages over “horizontal” urban farming for the former frees land for
incorporating more urban activities (i.e., housing more people, services, and amenities) [
7
]. Research
has revealed that designating urban land to farming results in decreased population density, which
leads to longer commutes. “If America replaced just 7.9% of its whopping one billion acres of
crop and pastureland with urban farms, then metropolitan area densities would be cut in half” [
4
]
(p. 71). Lower density living incurs higher energy use and generates more air and water pollution.
The National Highway Travel Survey (NHTS) indicates, “If we decrease urban density by 50%,
households will purchase an additional 100 gallons of gas per year. The increased gas consumption
resulting from moving a relatively small percentage of farmland into cities would generate an extra
1.77 tons of carbon dioxide per household per year” [
23
]. Despommier details space efficiency of
vertical farms. He suggested that a 30-story building (about 100 m high) with a basal area of 2.02 ha
(5 ac) would be able to produce a crop yield equivalent to 971.2 ha (2400 ac) of conventional horizontal
farming. This means that the production of one high-rise farm would be equivalent to 480 conventional
horizontal farms [24,25].
Buildings 2018,8, 24 5 of 36
Figure 1.
Food travels great distances from farm fields to dinner table. The map illustrates the case of
the travel of basic ingredients of a strawberry yogurt can (Adapted from [8]).
1.5.4. Health
Conventional farming practices often stress profit and commercial gain while paying inadequate
attention to inflicted harm on the health of both human and the natural environment [
7
,
8
,
10
]. These
practices repeatedly cause erosion, contaminate soil, and generate excessive water waste. Regarding
human well-being, the World Health Organization has determined that over half of the world’s farms
still use raw animal waste as fertilizer which may attract flies, and may contain weed seeds or disease
that can be transmitted to plants [
1
]. Consequently, people’s health is adversely affected when they
consume such produce.
Further, growing crops in a controlled indoor environment would provide the benefit of reducing
the excessive use of pesticide and herbicide, which create polluting agricultural runoff [
25
]. According
to Renee Cho, “In a contained environment, pests, pathogens, and weeds have a much harder time
infiltrating and destroying crops” [
25
]. When excess fertilizer washes into water bodies (e.g., rivers,
streams, and oceans), a high concentration of nutrients is created (called eutrophication), which could
disturb the ecological equilibrium. For example, eutrophication may accelerate the proliferation of
algae. However, when it dies, microbes consume algae and suck all the oxygen in water, resulting in
dead aquatic zones [8]. “As of 2008, there were 405 dead zones around the world” [25].
Further, indoor vertical farming employs high-tech growing methods that use little water
(about 1/10th of that used in traditional farming) by offering precision irrigation and efficient
scheduling
[25,26]
. This can have a significant ameliorative effect since demands on water will
increase as the urban population grows. Agricultural activities use more than two-thirds of the world’s
fresh water, and farmers are losing the batter for crop water because urban areas are expanding and
consuming more water. The water crisis is likely to become severer as climate change causes warmer
temperatures and proliferates more droughts [25].
1.5.5. The Ecosystem
Traditional agriculture has been encroaching upon natural ecosystems for millennia. According
to Dickson Despommier, “Farming has upset more ecological processes than anything else—it is the
most destructive process on earth” [
4
] (p. 7). In the past half century or so, the Brazilian rainforest
has been severely impacted by agricultural encroachment, with some 1,812,992 km
2
(700,000 mi
2
) of
Buildings 2018,8, 24 6 of 36
hardwood forest being cleared for farmland [
4
]. Despommier suggested that encroachment on these
ancient ecosystems is furthering climate change. In this way, indoor vertical farming can reduce the
agricultural impact on the world’s ecosystems by restoring biodiversity and reducing the negative
influences of climate change. If cities employed vertical farms to produce merely 10% of the ground
area they consume, this might help to reduce CO
2
emissions enough to develop better technological
innovations for improving the condition of the biosphere long-term. By eliminating fertilizer runoff,
coastal and river water could be restored, and fish stock of wild fish could increase. Wood, et al.
summarize this point by stating “The best reason to consider converting most food production to
vertical farming is the promise of restoring [the] services and functions [of ecosystems]” [26] (p. 110).
1.5.6. Economics
Proponents of the vertical farm also argue that it will supply competitive food prices [
27
].
The rising expense of traditional farming is quickly narrowing the cost gap. For example, when
vertical farms are located strategically in urban areas, it would be possible to sell produce directly to
the consumer, reducing transportation costs by removing the intermediary, which can constitute up to
60% of costs [
27
]. Vertical farms also utilize advanced technologies and intensive farming methods
that can exponentially increase production. Researchers have been optimizing indoor farming by
calibrating, tuning and adjusting a wide-range of variables including light intensity, light color, space
temperature, crop and root, CO
2
contents, soil, water, and air humidity [
27
29
]. In addition, vertical
farming provides an opportunity to support the local economy. Abandoned urban buildings can
be converted into vertical farms to provide healthy food in neighborhoods where fresh produce is
scarce. Additionally, the high-tech environment of indoor farming can make it fun to farm. Hence,
a technology-savvy younger generation has been enticed by the practice, grooming a new breed of
farmers. Further, vertical farming provides impetus in the development of innovative agricultural
technologies. Finally, it could reconnect city dwellers with nature through the activity of farming [
27
].
2. High-Tech Indoor Farming
2.1. Farming Methods
Researchers have advanced myriad methods of urban and vertical farming in the hopes of
contributing to sustainable food production. Advanced farming methods could provide greater yields
and use far less water than traditional farming [
17
,
18
]. The design, layout, and configuration of these
high-tech farms would provide optimal light exposure, along with precisely measured nutrients for
each plant. Designed to grow in a controlled, closed-loop environment, these farms would eliminate the
need for harmful herbicides and pesticides, maximizing nutrition, and food value in the process. Indoor
farmers could also “engineer” the taste of produce to cater to people’s preferences [
30
]. Researches
intend to develop, refine, and adapt these systems so that they can be ultimately deployed anywhere
in the world and provide maximum production and minimum environmental impacts. They represent
a paradigm shift in farming and food production and scholars view them as suitable for city farming
where land availability is limited [
5
]. These systems (mainly hydroponics, aeroponics, and aquaponics)
and associated technologies are rapidly evolving, diversifying, and improving (Table 1). The paper
explains these systems in a gradual manner, from simple to complex.
Buildings 2018,8, 24 7 of 36
Table 1. High-Tech Indoor Farming.
Farming
Method Key Characteristics Major Benefits Common/Applicable
Technologies
Hydroponics Soilless based, uses water as
the growing medium
Fosters rapid plant growth;
Reduces, even eliminates
soil-related cultivation
problems; Decreases the use of
fertilizers or pesticides.
Computerized and monitoring
systems; Cell phones, laptops,
and tablets; Food growing apps;
Remote control systems and
software (farming-from-afar
systems); Automated racking,
stacking systems, moving belts,
and tall towers; Programmable
LED lighting systems; Renewable
energy applications (solar panels,
wind turbines, geothermal, etc.);
Closed-loop systems, anaerobic
digesters; Programmable nutrient
systems; Climate control, HVAC
systems; Water recirculating and
recycling systems; Rainwater
collectors; Insect-killing systems;
Robots
Aeroponics
A variant of hydroponics;
it involves spraying
the roots of plants with mist
or nutrient solutions.
In addition to benefits
mentioned above, Aeroponics
requires less water.
Aquaponics It integrates aquaculture
(fish farming) with
hydroponics.
Creates symbiotic
relationships between the
plants and the fish; it uses the
nutrient-rich waste from fish
tanks to “fertigate”
hydroponics production beds;
and hydroponic bed cleans
water for fish habitat.
2.1.1. Hydroponics
Hydroponics is a method of growing food using mineral nutrient solutions in water without
soil. Encyclopedia Britannica defines hydroponics as “the cultivation of plants in nutrient-enriched
water, with or without the mechanical support of an inert medium such as sand or gravel” [
27
]
(p. 8). The term is derived from the Greek words hydro and ponos, which translates to “water doing
labor” or “water works”. The use of water as a medium for crop growing is not totally new, but the
commercial introduction of hydroponics arose only recently [
28
]. The National Aeronautics and Space
Administration (NASA) researchers have seen hydroponics as a suitable method for growing food in
outer space. They have been successful in producing vegetables such as onions, lettuce, and radishes.
Overall, researchers have advanced the hydroponic method by making it more productive, reliable,
and water-efficient.
Currently, the use of hydroponics in industrial agriculture has become widespread, providing
several advantages over traditional soil-based cultivation. One of the primary advantages of this
method is that it could eliminate or at least reduce soil-related cultivation problems (i.e., the insects,
fungus, and bacteria that grow in soil) [
28
30
]. The hydroponic method is also relatively
low-maintenance as well, insofar as weeding, tilling, kneeling and dirt removal are non-issues.
The hydroponic method also provides a less labor-intensive way to manage larger areas of
production [
8
,
31
,
32
]. Furthermore, it may offer a cleaner process given that no animal excreta are
used. Furthermore, the hydroponic method provides an easier way to control nutrient levels and pH
balance. According to Ebba Hedenblad and Marika Olsson, “In soil, many factors, such as temperature,
oxygen level, moisture, and microorganisms, affect how soil-fixed nutrients are made accessible to
plants since the nutrients are being dissolved in water through erosion and mineralization. Therefore,
the hydroponic method may result in more uniform [produce] and better yields, as the optimum
combination of nutrients can be provided to all plants” [30] (p. 17).
2.1.2. Cylindrical Hydroponic Growing Systems
The Volksgarden or cylindrical Omega Garden hydroponic growing system is a rotating-system
technology where plants are placed inside rotary wheels. When wheels spin, plants rotate around
centralized induction lights. The wheels rotate once every 50 min using a low-horsepower motor (it is
possible to run the wheels via wind turbines and solar panels). In advanced rotary systems, the “plants
rotate constantly and slowly around the light source, and their roots pass through a nutrient solution
Buildings 2018,8, 24 8 of 36
when they reach the bottom of the orbit. Turning at a constant rate allows the plants to take advantage
of orbitotropism (based on the impact of gravity on growth) to grow bigger, stronger and faster” [32]
(pp. 28–29). The Volksgarden system also provides a compact arrangement for the plants’ roots in rock
wool, thereby allowing the plants to grow more quickly than in traditional hydroponics [32].
Importantly, the “Ferris wheels”, can multiply their capacity by adding “extreme verticality”,
i.e., unit stacking. To appreciate the efficiency of the system experts have noted, “Each cylinder
holds 80 plants, and six cylinders are stacked together about 20 feet high at each station” [
32
] (p. 28).
This adds up to 480 units per station requiring only 3.4 m2(36 ft2) of space. Green Spirit Farms plans
to fit 200 stations compactly in one of its vertical farms to grow 96,000 plants per year. For comparison,
“conventional basil growers average 16,000 plants per acre (43,560 ft
2
), less than 20% of the production
Green Spirit Farms could have in just 7200 ft
2
” [
32
] (p. 28). Furthermore, the Volksgarden system
efficiently uses distilled water, requiring one-tenth the water used by traditional hydroponic systems.
“Their distillation process allows multiple reuses of water. Rather than discarding the nutrient-dense
liquid that remains after the produce has been harvested, it can be re-distilled and reused” [
32
] (p. 29).
Furthermore, the Volksgarden system entails virtually no evaporation because the liquid reservoir
for the growing system is closed. Additional water savings are provided by harnessing rainwater,
collectively minimizing the demand on municipal water systems [32].
2.1.3. Ultrasonic Foggers
Scientists have designed ultrasonic fogger systems to minimize maintenance and maximize yield.
They envision using them for myriad horticultural applications, including hydroponics, to provide
multiple benefits such as [33]:
Supplying upper roots with nutrient enriched fogs that penetrate deep into root tissues, keeping
them moist, well-nourished, and free of decay [16].
Promoting the growth of minuscule root hairs, which exponentially increase the root’s ability to
absorb water, nutrients, and exchange gases [32].
Reducing the use of water and nutrients by up to 50% [32].
Reducing the need for bulky and costly growing mediums [33].
Efficiently using space, as the units are compact and designed to be fed by a remotely located
reservoir [33].
By integrating ultrasonic foggers, hydroponic systems come close to aeroponic systems [33].
However, there are some concerns that the hydroponic method relies heavily on chemicals whereby
all of the nutrients supplied to the crop are dissolved in water [
29
]. A hydroponic system is based on
chemical formulations to supply concentrations of mineral elements [
30
]. Liquid hydroponic systems
utilize floating rafts and the Nutrient Film Technique (NFT), and they largely rely on non-circulating
water culture—though, new recirculation systems can be applied in NFT techniques [
30
]. Further,
some complain that the produce is tasteless because of all the added chemicals in the system and
because the roots do not get adequate oxygen [
30
]. These shortcomings are partially addressed by the
aeroponic method.
2.1.4. Aeroponics
Aeroponics is a technological leap forward from traditional hydroponics. An aeroponic system is
defined as an enclosed air and water/nutrient ecosystem that fosters rapid plant growth with little
water and direct sun and without soil or media [
34
]. The major difference between hydroponics and
aeroponic systems is that the former uses water as the growing medium while the latter has no growing
medium. Aeroponics uses mist or nutrient solutions instead of water, so it does not require containers
or trays to hold water. It is an effective and efficient way of growing plants for it requires little water
(requires 95 percent less water than traditional farming methods) and needs minimal space [
34
]. Plant
boxes can be stacked up in almost any setting, even a basement or warehouse.
Buildings 2018,8, 24 9 of 36
The stacking arrangement of plant boxes is structured so that the top and bottom of the plants are
suspended in the air, allowing the crown to grow upward and the roots downward freely. Plants are fed
through a fine mist of nutrient-rich, water-mix solution. Because the system is enclosed, the nutrient
mix is fully recycled, leading to significant water savings. This method, therefore, is particularly
suitable in water-scarce regions. An additional advantage of the aeroponic method is that it is free of
fertilizers or pesticides. Furthermore, research has revealed that this high-density planting method
makes harvesting easier and provides higher yields. For example, one of the aeroponic experiments
with tomato in Brooklyn, NY, resulted in quadrupling the crop over a year instead of the more common
one or two crops [34].
2.1.5. GrowCube
Recent research and technological development take the aeroponics method to a higher level of
productivity and efficiency. For example, GrowCube has proposed a new aeroponic prototype through
the high-tech cube, which contains five light plastic plates that spin via a rotisserie-esque wheel and
are lit by a strip of light-emitting diodes (LEDs) that provide the necessary light for photosynthesis [
34
].
At the top of the cube, a device sprays a nutrient-rich mist. The cube and its devices are controlled and
managed via computer and software, and sensors inside the cube communicate with the computer to
optimize the microclimate. The cube is also pressurized and equipped with an ultraviolet germicidal
lamp and a high-efficiency particulate absorption (HEPA) filter, as well as “bug-killing filters in the
pipes where the nutrient mixes are pumped” [34].
Consequently, the microclimate inside the cube is bug-free, making its produce free of pathogens.
Remarkably, IT companies are developing special apps and food growing food recipes, increasingly
available online. Consequently, the aeroponics system and the entire growing process can be optimized
remotely [
34
]. “When it comes time to planting, simply stick your seeds in a growing medium
. . .
and download the iOS app. From there, you can select and download a ‘grow recipe’ from the
cloud
. . .
Users are also encouraged to tweak and fork the recipes as they see fit, helping to improve
the growing and to offer variations. So if you want crisper lettuce, you can select that as an option” [
34
].
Furthermore, by conducting the work autonomously, the computer-controlled environment reduces
human errors and minimizes the effort of growing food [35].
With such a computerized system, almost anyone could become a sophisticated farmer. What
is more, the computerized system will help to “engineer” taste and other characteristics producing
crispy or spicy produce! GrowCube has managed to produce “herbs, flowers and foodstuffs like
wheatgrass, microgreens, pea-shoots and even 28 heads of lettuce”, and it plans to produce fruits
such as grapes [
34
]. The prototype is costly and will likely benefit from economies of scale when it is
produced in masses. Consequently, GrowCube plans to expand the project by producing hundreds of
these high-tech cubes [34].
2.1.6. Solar Aquaculture
Solar aquaculture involves growing high-quality fish protein in small, clean, translucent,
and controllable ponds that are exposed to sunlight. Microscopic green algae (nonflowering plants
lacking a true stem, roots, and leaves) live in the pond with the fish and grow by absorbing nutrients
from the water. In addition, sunlight that strikes the pond helps the algae to grow and causes the
water to become warmer. Fish and algae grow faster in warmer water. This method could be suitable
for vertical farms, enabling higher rates of production in limited spaces. A solar pond that is 1.5 m
high, 1.5 m in diameter (5 ft high, 5 ft diameter) and contains 2649 L (700 gal) of water can produce
an annual growth of 18 kg (40 lb) of fish [35].
In addition to supporting fish, solar ponds can serve indirectly as storage units for solar heat.
Algae capture about five percent of the entered solar energy while water absorbs the rest (95%).
The pond makes air cooler during the day, given that much of the incoming sunlight is stored as warm
water rather than hot air. In contrast, the pond warms the air at night as it releases heat. As such,
Buildings 2018,8, 24 10 of 36
heat from a solar pond can substitute for heating a greenhouse with gas, oil or wood or electricity,
thereby saving on energy. However, the solar pond requires extensive maintenance because of the fish
waste and some of the un-eaten food that transforms into waste. These problems are addressed by
closed-loop systems and the aquaponics method.
2.1.7. Aquaponics
Aquaponics is a bio-system that integrates recirculated aquaculture (fish farming) with hydroponic
vegetable, flower, and herb production to create symbiotic relationships between the plants and the
fish. It achieves this symbiosis through using the nutrient-rich waste from fish tanks to “fertigate”
hydroponic production beds. In turn, the hydroponic beds also function as bio-filters that remove gases,
acids, and chemicals, such as ammonia, nitrates, and phosphates, from the water. Simultaneously,
the gravel beds provide habitats for nitrifying bacteria, which augment the nutrient cycling and
filter water. Consequently, the freshly cleansed water can be recirculated into the fish tanks. In one
experimental project, aquaponics consisting of wetland pools containing perch and tilapia, whose waste
provided nutrients for greens, solved the principal problems of both hydroponics and aquaculture as
mentioned above [36] (Figure 2).
Figure 2. Basics of an aquaponic system (Adapted from [19]).
Researchers envision that the aquaponics system has the potential to become a model of
sustainable food production by achieving the 3Rs (reduce, reuse, and recycle). It offers bountiful
benefits, such as [36]:
Cleaning water for the fish habitat;
Providing organic liquid fertilizers that enable the healthy growth of plants;
Providing efficiency since the waste products of one biological system serves as nutrients for
a second biological system;
Saving water since water is re-used through biological filtration and recirculation. This feature is
attractive particularly in regions that lack water;
Reducing, even eliminating, the need for chemicals and artificial fertilizers;
Buildings 2018,8, 24 11 of 36
Resulting in a polyculture that increases biodiversity;
Supplying locally-grown healthy food since the only fertility input is fish feed and all of the
nutrients go through a biological process;
Facilitating the creation of local jobs; and
Creating an appealing business that supplies two unique products—fresh vegetables and
fish—from one working unit.
Consequently, aquaponics is preferable to hydroponics. However, aquaponics systems continue
to be at the experimental stage, having had limited commercialized success. This is because the
technologies necessary to build aquaponics systems are relatively complex, requiring the mutual
dependence of two different agricultural products. For this reason, aquaponics also requires intensive
management [36].
2.2. Lighting Technologies
One of the important components of successful vertical farming is sound lighting. Available
LED technologies provide only 28% efficiency, an efficiency rate that should be increased to about
50–60%, at a minimum, to make indoor farming methods cost-effective [
37
]. Fortunately, experimental
developments in LEDs have reached that mark [
37
,
38
]. Dutch lighting engineers at Philips have
produced LEDs with 68% efficiency. Such an increase in lighting efficiency will dramatically cut costs.
Also, a Dutch-based group called PlantLab has recently invented a lighting technology that could
help to grow food on a small footprint. According to Michael Levenston, “This invention replaces
sunlight with LEDs that produce the optimal wavelength of light for plant growth. Contrary to the
sun, traditional assimilation lighting, and TL lighting LED only omits one color of light. No energy is
wasted with light spectra that are not used
. . .
by the plant” [
38
]. As such, the new lighting technology
provides the correct lighting colors plants need for photosynthesis—blue, red, and infrared light.
Furthermore, new “induction” lighting technology simulates the color spectrum of sunlight to
foster the growth of vegetables and fruits. “The light uses an electro-magnet to excite argon gas as
its light source, instead of a filament. For this reason, [it] uses much less energy and can last up
to 100,000 hours, twice as long as an LED light” [
39
]. It also generates more heat than LED light,
but less than an incandescent bulb. Therefore, the lights create enough heat for growing plants without
wasting energy to heat the entire building. Moreover, the light units are calibrated to create an “ideal”
microenvironment by producing high-quality lighting that is similar to daylight. These units are also
long lasting, with a life span of about one decade, and are sold at affordable prices.
2.3. Farming Operation
Researchers predict that farming operations will be fully automated in the near future.
For example, monitoring systems will be widely implemented (in the form of sensors near each
plant bed) to detect a plant’s need for water, nutrients and other requirements for optimal growth and
development. Sensors can also warn farmers by signaling the presence of harmful bacteria, viruses or
other microorganism that cause disease. Also, a gas chromatograph technology will be able to analyze
flavonoid levels accurately, providing the optimal time for harvesting. These specific technologies are
not totally new. Their development has been on going and will likely proliferate in the near future [
39
].
2.4. Farming from Afar
One of the promising ideas under development is “farming from afar”. The cell phone, its software
and apps, will ultimately handle much of the day-to-day tending of crops, and vertical farmers will
be able to manage multiple farms remotely. New apps will allow farm managers to adjust “nutrient
levels and soil pH balance from a smartphone or tablet, and sound alarms if, say, a water pump fails
on a vertical-growing system
. . .
So if I’m over in London, where we
'
re looking for a future vertical
farm site to serve restaurants, I’ll still be able to adjust the process in Michigan or Pennsylvania”,
Buildings 2018,8, 24 12 of 36
as Paul Marks explained [
40
]. Farming from afar will drastically reduce operational costs by reducing
labor and will provide considerable convenience, flexibility, and efficiency in managing farms. Further,
by engaging new information technology and working with new online applications, farming could
become an exciting and fun activity.
2.5. “Closed-Loop Agricultural” Ecosystems
“Closed-loop agricultural” ecosystems intend to mimic natural ecosystems that treat waste as
a resource. Similar to aquaponics, the waste of one part of the system becomes the nutrients for the
other. The closed-loop system recycles and reuses nearly every element of the farming process—dirty
water, sewage, and nutrients. Food waste can also be converted to compost. In a closed-loop system,
everything remains in the system, leading to a zero-waste outcome. This results not only in drastic
decreases in waste but also in the creation of energy and other byproducts such as bedding and
potting soil.
Anaerobic Digester
An anaerobic digester is a biogas recovery system that converts food waste into biogas to produce
power and heat [
41
]. The Plant, a vertical farm in Chicago, has employed an anaerobic digester that
captures the methane from 27 tons of daily food waste to produce electricity and heat. Figure 3
illustrates how The Plan has integrated an anaerobic digester in its employed close-loop system
(also see Section 3.2 on The Plant). Similarly, Great Northern Hydroponics (GNH), in Quebec, Canada,
has employed a cogeneration machine that reduces its heating costs and reliance on fossil fuels. GNH’s
power production has increased such that it is capable of selling electricity back to the Ontario Power
Authority, decreasing the province’s dependence on fossil fuels.
Main features of the closed-loop system:
At the heart of the system is an anaerobic digester that turns organic materials into biogas, which
is piped into turbine generator to make electricity for plant grow light.
The plants make oxygen to the Kombucha tea brewery, and Kombucha tea brewery makes CO
2
to
the plant.
Waste from the fish feeds the plants and the plants clean the water for the fish.
More fish waste goes to the digester along with plants’ waste, waste from outside sources and
spent grain from the brewery.
Spent barley from the brewery feeds the fish.
Sludge from the digester that becomes algae duckweed also feeds the fish.
Along electricity, the turbine makes steam which is piped to the commercial kitchen, brewery,
and the entire building for heating and cooling.
Therefore, the kitchen produces Kombucha tea, fresh vegetables, fish, beer, and food, all with
no waste.
2.6. Renewable Energy
Some vertical farms have implemented, and others have proposed employing wind turbines and
photovoltaic panels to supply power. Other systems, such as thermal systems that collect solar heat
and warehouse refrigeration exhaust, are also under consideration.
2.7. Integration within City Infrastructure
Future proposals, for example by Plantagon, envision the integration of vertical farms with the
city symbiotically. The proposal envisions that the vertical farm will collect organic waste, carbon
dioxide, manure, CO
2
, and excess heat from plants and factories, and transform these into biogas for
heating and cooling. In this way, the vertical farm not only could grow food but also help to develop
sustainable solutions for better energy, heat, waste, and water use (Figure 4).
Buildings 2018,8, 24 13 of 36
Figure 3.
An illustration of an integrated food production through a closed-loop system (Adapted
from [41]).
Figure 4.
The proposed vertical farm in the downtown of Linköping, south of the capital Stockholm in
Sweden by Plantagon provides an industrial symbiotic system. Partnership will be established between
Plantagon, local energy company and local biogas plant. The greenhouse gets district heating from the
power plant that runs through a major road, it gets excess heat and carbon dioxide from the biogas
plant, and the leftover from the greenhouse goes into the biogas digestor. (Adapted from [42]).
Buildings 2018,8, 24 14 of 36
2.8. Redefining Vertical Farms
The aforementioned technologies are redefining the vertical farm as “a revolutionary approach
to producing high quantities of nutritious and quality fresh food all year round, without relying on
skilled labor, favorable weather, high soil fertility or high water usage” [
24
]. These new systems add
advantages to vertical farming, summarized in Table 2.
Table 2. Advantages of high-tech vertical farming systems [42].
1. Reliable harvests Controlled indoor environments are independent of outside weather conditions and would provide
consistent and reliable growing cycles to meet delivery schedules and supply contracts.
2. Minimum
overheads Production overheads would decrease by 30%.
Low energy usage
The use of high efficiency LED lighting technology ensures minimum power use for maximum plant
growth. Computer management of photosynthetic wavelengths, in harmony with phase of crop growth,
further minimizes energy use while ensuring optimized crop yields.
Low labor costs
Fully automated growing systems with automatic SMS text messaging would require manual labor only
for on-site planting, harvesting, and packaging.
Low water usage Vertical farms would use around 10% of the water required for traditional open field farming.
Reduced washing
and processing Vertical farms would employ strict bio-security procedures to eliminate pests and diseases.
Reduced transport costs Positioning of facilities close to the point of sale would dramatically decrease travel times, reducing
refrigeration, storage and transport costs in the process.
3. Increased
growing areas Vertical farms would supply nearly ten times more growing area than traditional farms.
4. Maximum crop
yield
Irrespective of external conditions, vertical farms can provide more crop rotations per year than open
field agriculture and other farming practices. Crop cycles are also faster due to controlled temperature,
humidity, light, etc.
5. Wide range
of crops The vertical farm would provide a wide range of crops.
6. Fully integrated
technology The vertical farm would be fully monitored, controlled, and automated.
Optimum air quality The temperature, CO2, and humidity levels of the vertical farm would be optimized at all times.
Optimum nutrient and
mineral quality
The vertical farm would use specially formulated, biologically active nutrients in all crop cycles,
providing organic minerals and enzymes to ensure healthy plant growth.
Optimum water quality All fresh water’s contaminants would be removed before entering the vertical farm.
Optimum light quality
High-intensity low-energy LED lighting would be specifically developed and used for maximum growth
rates, high reliability, and cost-effective operations.
3. Vertical Farm Project Examples
Several cities have embarked on vertical farming projects. The following narrative provides a
concise summary, and Table 3offers a list of these projects.
Table 3. Summary of examined projects.
Vertical Farm Location Type Status
Nuvege Kyoto, Japan LR Built
PlantLab Den Bosch, Holland LR Built
Sky Greens Singapore LR Built
Green Spirit Farms New Buffalo, Michigan, USA LR Built
FarmedHere Bedford Park, Illinois, USA LR Built
The Plant Chicago, Illinois, USA LR Built
Green Girls Produce Memphis, Tennessee, USA LR Built
Brooklyn Grange Brooklyn, New York, USA RT Built
Gotham Greens Brooklyn, New York, USA RT Built
Plantagon Sweden HR Proposed
La Tour Vivante France HR Proposed
Harvest Green Tower Vancouver, Canada HR Proposed
Skyfarm Toronto, Canada HR Proposed
Pyramid Farm NA HR Proposed
TBD Philippine HR Proposed
LR = Low Rise; HR = High Rise; RT = Rooftop.
Buildings 2018,8, 24 15 of 36
3.1. Modest-Scale Vertical Farms
Companies interested in modest-scale vertical farming are proliferating around the world.
For example, Nuvege in Kyoto, Japan, is a 2787 m
2
(30,000 ft
2
) hydroponic facility with 5295 m
2
(57,000 ft
2
) of vertical grow-space that produces a variety of lettuces in a safe environment from the
nearby Fukushima nuclear plant [
25
]. PlantLab in Den Bosch, Holland, is a three-story underground
vertical farm that uses advanced LED technology that calibrates light composition and intensity to
precise needs, entirely removing the wavelengths of sunlight that prevent plant growth [
25
]. The farm
employs an automated system that monitors and controls numerous variables including humidity,
CO
2
, light intensity, light color, air velocity, irrigation, nutritional value, and air temperature [
25
].
The high-tech farm produces a yield three times the amount of the average greenhouse while reducing
water use by 90%.
3.1.1. Sky Greens
One of the promising vertical farms is the Sky Greens of Singapore. As a small island, but with
a population of over five million, Singapore faces potential issues of food security. With land at
a premium, limited space for farming is available. Singapore produces only 7% of the food it consumes,
and only 250 acres of the island are devoted to farming. The remaining need is supplied by food
imports from all over the world. However, the transportation costs of food are becoming increasingly
prohibitive. For these reasons, Singapore has been taking vertical farming seriously. Although
Singapore is an extreme case, it represents a looming problem facing myriad cities worldwide [26].
Sky Greens is Singapore’s first commercial “tropical vegetable urban vertical farm
. . .
to achieve
enhanced green, sustainable production of safe, fresh and delicious vegetables, using minimal land,
water, and energy resources” [
43
]. The five-year-old farm is 3-stories tall (9 m or 30 ft) and uses
a method called “A-Go-Gro (AGG) Vertical Farming” that utilizes translucent green houses to grow
tropical leafy vegetable year-round at significantly higher yields than traditional farming methods.
Sky Greens is capable of producing one ton of fresh veggies every other day. It supplies a variety of
tropical vegetables including Chinese cabbage, Spinach, Lettuce, Xiao Bai Cai, Bayam, Kang Kong,
Cai Xin, Gai Lan and Nai Bai. By providing high-quality produce at relatively affordable costs, the farm
has thrived and intends to expand its production, providing a wider variety of vegetables.
Structurally, the AGG system consists of tall aluminum A-frames that can be as high as 9 m
(30 ft) tall with 38 tiers of growing troughs that contain various growing media—soil and hydroponics.
The A-frame system takes up only 5.6 m
2
(60 ft
2
), making it ten times more efficient than conventional
farming [
43
]. The troughs slowly rotate around the aluminum frame (about three rotations per
day) to ensure that the plants obtain uniform sunlight. Such continuous exposure also reduces or
even eliminates the need for artificial lighting in some areas of the building. Rotation is powered
by a patented low carbon hydraulic system that contains trays of plants. The hydraulic system is
an ancient technology empowered with a modern twist; it is a closed-loop that makes efficient use of
gravity and consumes little energy. Each 9-m (30 ft) tower uses only 60 W of energy and, therefore,
the owner spends only about “$360/month ($3/tower) on electricity” to power the farm [43].
In addition to providing commercial benefits, Sky Greens is engaged in educational programs
in the surrounding neighborhoods where students visit the farm, getting exposure and hands-on
experience in transplanting, harvesting, and understanding the power of science and technology in
creating green urban solutions. According to Sky Green’s website, the project provides numerous
economic and environmental benefits, summarized in Table 4. The project started as a prototype
developed jointly with Agri-Food and the Veterinary Authority of Singapore (AVA) in 2010. Sky Greens
together with AVA won the Minister for National Development’s Research & Development Award
2011 (Merit Award) for Vertical Farming. Sky Greens promises to become a viable food supplying
option [43,44].
Buildings 2018,8, 24 16 of 36
Table 4. The environmental and socioeconomic benefits of the Sky Greens vertical farm project [43].
Environmental Benefits
Environmentally
friendly and high-tech
Sky Greens observes, learns and works with nature to achieve sustainability for the good of the
environment to grow safe, high-quality vegetables using green technologies.
Low energy usage Outdoor green houses have abundant sunlight in the tropics. The A-Go-Gro system uses
patented low carbon hydraulic green technology to power the rotation of the tower at very low
energy costs, while still allowing the plants to receive abundant sunlight.
Low water usage As the troughs of plants rotate, irrigation occurs using an innovative flooding method, using
very little water. Water is also recycled and reused.
Good waste &
water management Sustainable water management practices are utilized with all organic wastes being composted
at the farm to ensure the use of safe, high-quality fertilizers.
Green technologies Green technologies have been stringently implemented at the farm to achieve the three Rs
(reduce, reuse and recycle).
Socioeconomic Benefits
Increased productivity
The production yield of Sky Greens Farm is 5 to 10 times greater per unit of area than traditional
Singaporean farms that growing leafy vegetables in a conventional fashion.
Tasty Vegetables Tropical leafy vegetables are grown in special soil-based media, which contribute to good
tasting vegetables, suitable for stir-fry and soups. The vegetables are harvested every day and
delivered almost immediately to retail outlets for consumers.
Year-round production
As the vertical farm structures are in protected-outdoor green houses, the vegetables are grown
in a controlled environment, protected from pests, winds and floods.
Consistent and
reliable harvest A steady supply of fresh leafy vegetables is assured as growing takes place in a
controlled environment.
Easy to install and easy
to maintain The modular A-frame rotary system allows quick installation and easy maintenance.
Better ergonomics
& automation The rotary system allows the troughs to be immediately adjusted for easy harvesting.
Automation increases the productivity of workers per ton of vegetables grown.
Space savings The footprint of the vertical system is small but can produce significantly more per unit area
than traditional farms. It can also be customized to suit different crop requirements and
varying environments.
In the United States, cities such as New York, Chicago, Milwaukee, and others are becoming
pioneers of vertical farming by repurposing vacant urban warehouses, derelict buildings and high-rises
to grow food. With so much vacant space available, the cost of property is often affordable to buy or
rent. Within the buildings, vertical farmers build tall structures with several levels of growing beds,
often lined with artificial lights, to grow crops and “microgreens”, i.e., salad vegetables such as arugula,
Swiss chard, mustard, beetroot, and sunflowers. Indoor vertical farming is playing an important role
in spurring economic development by repurposing vacant industrial buildings, supplying fresh and
healthy food and providing jobs in distressed areas. Among the pioneering vertical farm projects
to spread across the U.S. are those carried by companies such as Green Spirit Farms, FarmedHere,
The Plant, and Green Girls.
3.1.2. Green Spirit Farms
Located in New Buffalo, Michigan, Green Spirit Farms (GSF) is a professional food company
that has openly embraced vertical farming. The New Buffalo facility has grown out of a former
plastic factory. The building contains about 3716 m
2
(40,000 ft
2
) of space and sits on an 11-ha (27-ac)
site. As standard practice, GSF will enter older vacant industrial or commercial buildings to supply
produce nearby urban markets. It aims to provide local markets with high quality, fresh, pesticide-free,
non-genetically modified organism (GMO) foods at affordable prices. The company chooses to grow
products with a high local demand like lettuce, basil, spinach, kale, arugula, peppers, tomatoes, stevia,
strawberries, and Brussel sprouts. It sells its produce locally to grocery stores and restaurants and to
a host of small “Harvest Markets” which sells directly to consumers. GSF runs vertical organic farms
in Atlanta, Philadelphia, Canada, and the United Kingdom [
45
]. The company has a strong belief in
Buildings 2018,8, 24 17 of 36
vertical farming. According to Green Spirit Farms’ Research and Development Manager Daniel Kluko,
the future of farming is heading in one clear direction: the vertical. “If we want to feed hungry people
this is how we need to farm
. . .
We cut out the risk of traditional farming, the labor, and most of the
equipment costs
. . .
This is not a niche business, it’s not something novel, this is a necessity for the
human race to continue to live” [46].
GSF has advanced several technologies to grow vegetables. These include the Volksgarden Rotary
Garden unit, referred to as a Rotary Vertical Growing Station (RVGS), and a multi-level tray system,
referred to as a Vertical Growing Station (VGS). GSF has lately commercialized rotary and vertical
farming systems using patented techniques to grow local vegetables, herbs, and some fruits, and has
opened vertical farms in repurposed industrial buildings, including one in East Benton, Pennsylvania.
The new facility constitutes a major expansion compared to GSF’s first facility in New Buffalo, Michigan,
containing 1715 vertical growing stations that will produce herbs, leafy vegetables, peppers and
tomatoes, the equivalent of 81 ha (200 ac) of farmland harvested year-round. This is enabled by
facility’s efficiency, which uses “98 percent less water, 96 percent less land, and 40 percent less energy”
than would be required by traditional agriculture [
46
]. It is expected that the facility will create over
100 jobs to support the local economy. GSF has invested about $27 million to establish the vertical
farm and received financial aid including a $300,000 Pennsylvania First Program grant, $303,000 in
Job Creation Tax Credits, and a $45,450 Guaranteed Free Training grant to train new employees [
47
].
The location has appealed to Green Spirit because of its proximity to large local markets, with most of
its produce selling within approximately 75 miles of the farm [
47
]. In summary, the vertical farm project
provides a useful example of adaptive reuse established through a strong public-private partnership.
This has been made possible through the collaboration between GSF and several agencies including
the Commonwealth of Pennsylvania, Lackawanna County, Benton Township, and the Greater Scranton
Chamber of Commerce.
3.1.3. FarmedHere
FarmedHere is a company that was founded in 2011 and has recently expanded to three locations
in Illinois: Englewood, a Chicago Southside neighborhood; Flanagan in downstate Illinois; and recently
in Bedford Park, a Southwest Chicago suburb. As the company grows, it expects to supply 6% or
more of the Chicago area’s demand for premium green and culinary herbs. The company also hires
local youths through Windy City Harvest, a Chicago Botanic Garden-led urban agriculture-training
program targeted to underserved youths. FarmedHere received the USDA (the U.S. Department of
Agriculture) Organic Certification at the end of 2012 [
48
]. The company’s product is spreading in
several grocery stores including Whole Foods, Chicago-area Mariano’s Fresh Market, Green Grocer,
and possibly soon at Trader Joe’s and Meijer. FarmedHere was able to receive financial support from
Good Food and Whole Foods, the farm’s largest customers. The company expects that it has a market
niche given the recent generational demands for healthy and organic foods. These new businesses also
expect to obtain subsidies from tax-increment financing as well as property-tax breaks for reviving
industrial properties [48].
Bedford Park’s facility is about 8361 m
2
(90,000 ft
2
), much larger than both the first facility in
Englewood (371 m
2
(4000 ft
2
)) and the second facility in Flanagan (929 m
2
(10,000 ft
2
)). Bedford Park’s
facility, about 24 km (15 mi) from downtown Chicago, is now hyped as the first of its kind and the
largest indoor vertical farm in America [
48
]. It was opened in 2013 and is expected to become a
new model for growing produce efficiently in a high tech manner. The farm resides in a two-story,
windowless warehouse, and is designed to occupy the full extent of the space. Currently, the farm
consists of two structures with large growing beds lit by fluorescent lighting. The first structure
contains the aquaponics system where water circulates between fish tanks, feeding plants that rest in
cutouts on Styrofoam “floats” above. The second structure contains the aeroponics system, with water
misters underneath that spray the exposed roots of the plants. Workers plant the seeds and grow
seedlings on racks that then are transferred into the growing systems. After about a month, the crops
Buildings 2018,8, 24 18 of 36
are harvested and packaged manually in a cooling room at the facility, and then shipped the next
morning to grocers in Chicago’s metropolitan area [49].
By stacking aquaponics and aeroponics systems vertically, the facility contains 13,935 m
2
(150,000 ft
2
) of growing space, or about 1.4 ha (3.5 ac). Planting in a controlled environment with
ideal humidity and temperature ensures optimal growth. FarmedHere produces about 136,078 kg
(300,000 lb) of leafy greens and plans to grow to what will eventually amount to more than 453,592 kg
(a million pounds) of chemical, herbicide and pesticide-free leafy greens yearly [
49
]. It also plans to
expand by producing peppers, tomatoes, and other popular vegetables. Their aquaponics produces
fish and organic herbs—basil and the like—while their aeroponics produces leafy greens like arugula
and watercress. For space efficiency, plants are grown on six shelves that receive artificial fluorescent
lighting and that are attended by workers using scissor lifts. The aquaponics method filters the
nitrogen-rich waste of the tilapia fish and uses it to feed plants, and the hormone-free tilapia are bred
in four 3028-L (800-gal) tanks, where water is ultimately recycled to create a closed loop that reduces
water use by 97%. Therefore, the system is efficient in its use of water and space.
These new facilities also provide “on-demand farming” meaning they are flexible and responsive
to market demands. For example, demand may suddenly increase for particular types of mixed greens
or mini greens. “We could change the whole system ... and pretty much within the next 14 to 28 days,
we [would] have a full grown plant, whatever the market requires” [
50
]. However, the prime obstacle
these farms face remains the electricity needed to grow the plants and heat the space. Because of
exorbitant energy bills, some indoor farms have been closed down. Dickson Despommier, in his book
“The Vertical Farm: Feeding the World in the 21st Century”, stresses the fact that energy remains the
primary hurdle [
4
]. Nevertheless, vertical farmers are trying to find solutions by exploring solar, wind
and methane gas as ways to generate electricity, or by supplementing artificial light with natural light
through windows and skylights. Other farmers are experimenting with flickering lights sufficient to
grow plants with little power.
3.2. The Plant
Located in the heart of Chicago’s derelict stockyards, the almost century old site of The Plant
has a long history of food production as a former meatpacking facility and the former home of
Peer Foods. The four-story, 8686 m
2
(93,500 ft
2
) red brick warehouse is now set to become a major
net zero vertical farm where the operation is fueled by food waste [
51
]. The zero-energy facility relies
on an on-site Combined Heating and Power (CHP) system that contains a large anaerobic digester
that converts food waste into biogas to power, heat and cool the building. The anaerobic digester
captures the methane from 27 tons of food waste daily and 11,000 annually and burns it to produce
electricity and heat. The Plant plans to turn the facility into a food business incubator, research lab and
educational and training facility for vertical farming. The building’s transformation, which started in
2010, was completed in 2016 [51].
The Plant is currently producing greens, mushrooms, bread, and Kombucha tea. Eventually,
the facility will combine a tilapia farm, beer brewery, Kombucha brewery, communal kitchen,
an aquaponics system, and green energy production. “We’re working to show what truly sustainable
food production and economic development looks like by farming inside an old meatpacking facility,
incubating small craft food businesses, brewing beer and kombucha, and doing it all using only
renewable energy that we make onsite. By connecting outputs of one business to the inputs of another,
we are harnessing value from materials that most people would throw away” [
51
]. The conversion of
the space into a vertical farm and food business incubator was partly made possible by a $1.5 million
grant from the Illinois Department of Commerce and Economic Opportunity (DCEO) to support the
development of a comprehensive renewable energy system [51].
Buildings 2018,8, 24 19 of 36
3.3. Green Girls
Green Girls Produce, a professional food company, is Tennessee’s first indoor vertical farm
that supplies local restaurants with a year-round fresh produce in an effort to improve the health of
Memphians and to fight urban blight. The 60,000-ft
2
facility is located in Memphis’ Historic Downtown
on the 4th floor of the Emerge Building. Restaurants have a desire for microgreens, which give meals
an additional flavoring and pizzazz [
52
]. “Chefs love them because they make a boring dish pop, they
add intense flavor, texture and vivid color
. . .
On top of that, they are nutritious with up to 40 times
the nutrients and vitamins of their mature counterparts” [
52
]. However, restaurants often refrain
from purchasing microgreens given their high costs. Restaurants typically pay about $100 a pound
for microgreens. The vertical farm reduces the costs down to below $40 per pound. Green Girls
estimates a revenue of about one million dollars a year. It supplies affordable microgreens and makes
a profit because of efficient technologies provided by automated, re-circulating hydroponic systems
that require only two employees to run. It is characterized by being clean, efficient in its water use
(Green Girls uses 90% less water than conventional farming) and green in its energy use, employing
only LED lighting [52].
3.4. Rooftop Farming
Rooftop farming simply involves the growing of fruits and vegetable on a rooftop. With a dearth
of suitable urban farming land, roofs are increasingly being seen as a plausible space for growing food
and a proactive measure in building a sustainable future for cities. Indeed, an abundance of unused
rooftop spaces prevails. For example, Honolulu’s buildings alone contain more than 1,579,351 m
2
(17,000,000 ft
2
) of rooftops. Consequently, in recent years, a great number of rooftop farms have sprung
up and some green roofs have been transformed into rooftop farms [5355].
Overall, converting green roofs into rooftop gardens is a rising trend that aims to “scale up”
urban agriculture. Similar to green roofs, rooftop farms are viewed as a necessity for combatting
the heat-island effect, to mitigate stormwater runoff and to insulate buildings. In addition to these
environmental benefits, rooftop farming provides the benefits of supplying the community with fresh
produce and promoting modest-scale urban agriculture as well as providing tangible connections to
food, See Table 5. Among the common vegetables grown on rooftops are kale, collard greens, carrots,
radishes, peppers, beans, beets, cherry tomatoes, and various herbs [
56
]. Though, it should be noted
that a slight distinction between a vertical garden and a vertical farm exists. While both grow plants
vertically, the former not always produces fruits and vegetable, and the latter does that exclusively.
Vertical farms usually occupy larger areas than that by vertical gardens. Nevertheless, the produce of
both types (vertical gardens and vertical farms) is offered to local communities, stores, and restaurants.
Rooftop farming is not a wholly original idea given that its history goes back to the ziggurats
of ancient Mesopotamia and the Hanging Gardens of Babylon. To this day, however, continuing
challenges in implementing rooftop farms persist. The structure must be strong enough to support the
heavy weight of soil and greenhouse structures. Usually, the edges of rooftops are suitable to support
moderate loads, but the central areas may need extra reinforcement [57].
Furthermore, a rooftop requires building access, which imposes logistical issues, liability, weather
conditions, and insurance risks. Zoning codes could also be obstacles to obtaining permits. For these
reasons, urban farmers are struggling to create efficient farming systems while making a profit.
Balancing costs and profits indicates that not every green roof is well suited for farming. For example,
in 2012 Local Garden, a rooftop farm that was opened in Vancouver, Canada, was recently closed due
to economic reasons. Overall, rooftop farming is still a work in progress, but it has great potential as
an urban farming system [58].
Buildings 2018,8, 24 20 of 36
Table 5. Summary of the benefits of rooftop farms [53].
Environmental Benefits
Energy
Conservation
The use of green roofs compared to conventional roofing surfaces significantly affects the energy
balance within a building. Studies have revealed that green roofs have the potential to reduce a
building’s energy use by as much as 30%.
Stormwater
Management
A green roof absorbs rainwater and helps to prevent sewer system back-ups and contaminated
stormwater overflow. Green roofs can also help to prevent catastrophic environmental events,
such as the Ala Wai Canal sewage spill disaster.
Fossil Fuel
Reduction
A rooftop farm can grow hyper-local foods. Growing Low Food Mile organic produce substantially
reduces the fossil fuel consumption associated with the traditional food transportation system.
Global Warming
Green roofs sequester carbon from the atmosphere, lower the levels of carbon dioxide in the air,
eliminate the build-up of greenhouse gases, and keep city temperatures cooler by effectively
reducing the “Urban Heat Island Effect”.
Biodiversity By replacing inorganic, lifeless roofs with living and thriving green spaces, green roofs support
increased biodiversity in urban environments—offering a habitat for a multitude of
organisms—from birds to butterflies to countless other beneficial insects.
Environmental
Stewardship Organic rooftop farming protects soil and water from toxic pesticides, herbicides, fungicides,
and other dangerous chemicals typically used in conventional farming.
Socioeconomic Benefits
Community A rooftop farm is a beacon of sustainable community building that creates tangible connections
between farmers and consumers. Rooftop farms have the power to do this throughout the city,
no matter how scarce or valuable the land.
Local Food
Economy
Rooftop farms generate revenue for local farmers and businesses. In this way, rooftop agriculture
can also be viewed as an emerging green technology that creates jobs and improves food
self-sufficiency by providing organic and Hyper-Local produce.
Nutrition and
health
As an example, the produce of FarmRoof™ is extraordinarily nutritious and healthy. Thanks to a
special soil that has been infused with minerals, trace elements, omegas, proteins and
microorganisms, all of their crops are packed with enzymes, antioxidants, nutrients, and minerals.
Aesthetics and
Beauty
Supplanting inorganic, lifeless roofs with vibrant greenery, green roofs can beautify cityscapes and
balance an otherwise bleak horizon of concrete and tar.
3.4.1. Brooklyn Grange
Several rooftop farms have recently sprung up in New York City, the largest of which is Brooklyn
Grange rooftop farm—about one acre in size—and is claimed to be the world’s largest rooftop
garden [
59
]. Placed on top of a six-story warehouse that was built in 1919, Brooklyn Garage grows
a wide-range of “organic produce that includes 40 varieties of tomatoes, peppers, fennel, salad greens,
kale, Swiss chard, beans and a variety of delicious root vegetables such as beets, carrots, and radishes,
as well as herbs” [
42
]. Their produce is grown in 19 cm (7.5 in) deep beds with Rooflite soil [
59
,
60
].
“Rooflite is a lightweight soil composed of organic matter compost and small porous stones which
break down to add trace minerals that are needed for the produce to grow into a healthy and mature
state” [60]. Brooklyn Grange is thriving and plans to expand its operation [61].
3.4.2. Gotham Greens
Gotham Greens is a 1394 m
2
(15,000 ft
2
) facility atop a two-story building in Greenpoint, Brooklyn,
New York. Constructed in 2011, it is claimed to be the first rooftop hydroponic commercial farm that
uses technologically sophisticated Controlled Environment Agriculture (CEA) in an urban setting
in the United States. The facility enjoys unusual farming efficiencies given that it uses less square
footage to grow 7–8 times more food than traditional farming, providing produce year-round that
is pesticide free [
62
,
63
]. Gotham Greens offers the advantage of growing summer vegetables in the
winter, enhancing New York City’s barren landscape at this time, and plans to produce 80–100 tons of
pesticide-free, premium-quality lettuce, salad greens, and herbs yearly. Gotham Greens is not only
aiming to provide quality produce but also to save on energy by employing advanced computer
systems that control heating, cooling, irrigation and plant nutrition, while utilizing on-site solar
Buildings 2018,8, 24 21 of 36
photovoltaics. Energy use is reduced further by providing natural ventilation, double-glazing,
and thermal insulation that is supplied by the rooftop farm and through high-efficiency pumps
and fans. As such, the facility optimizes energy use and consumes less land and water than that of
a conventional farm. These energy-saving measures are particularly suitable for New York City given
its rapid increase in energy costs. Because of these energy saving innovations, Gotham Greens will
likely be able to reduce its production costs significantly [
45
,
46
]. Interestingly, Gotham Greens was
the only fresh food supplier in New York during the Sandy Hurricane. This highlights the benefits
of protected agriculture in urban areas—particularly as we face climate change—while open-air
agriculture can suffer from weather damages [64].
3.5. Multi-Story Farms
As mentioned earlier, there have been an increasing number of proposals for multi-story farms
that remain ideas on the drawing board. This is due, in large part, to the fact that these ideas are not yet
economically feasible. However, some companies have taken this endeavor seriously and are on the
verge of implementing some of these visionary ideas. Among the pioneering companies is Plantagon.
3.5.1. Plantagon
Founded in 2008 in Stockholm and headed by Hans Hassle, Plantagon is a Swedish vertical
agriculture company that has flourished through the establishment of offices in cities around the
world, including Shanghai, China, and Singapore. Plantagon collaborates with other companies such
as SymbioCity and SWECO that are also devoted to finding new methods of vertical farming and
in clean technologies (Figure 5). It has also established research ties with academic institutions such
as Linköping University in Linköping, Sweden, Nanyang Technological University in Singapore,
and Tongji University in Shanghai, China. The company participated in Shanghai’s World Expo 2010
and won the Globe Sustainability Innovation Award that same year. It also won a Silver Stevie Award
for being Europe’s “most innovative company” in 2012 [65].
Figure 5.
Map of global cleantech innovation ranking (on a scale from 1 to 5, with 5 being the highest
score). (Adapted from [65]).
3.5.2. Organizational Structure
Plantagon has embraced an innovative organizational structure, which they call “companization”,
that combines two legally bound units, a profit-driven company called Plantagon International AB,
Buildings 2018,8, 24 22 of 36
and a non-profit association called Plantagon Non-profit Association [
65
]. This “companization”
aims to unite profit-driven comercial forces with nonprofit organizational values [
66
]. It is a blend
between the top-down action oriented commercial organization and the bottom-up inclusive and
democratic nonprofit association. The two units of the company are dependent upon one another,
thereby making it difficult for the company to act irresponsibly and unethically. Plantagon is also tied
to overarching ethical frameworks provided by the “UN Global Compact” and the “Earth Charter” in
their articles of association and statutes. Their board members, from both the profit and nonprofit units,
constantly co-review financial and social performance, bringing “moral questions to the otherwise
purely economic forum [65,66] (Figure 6).
3.5.3. Technical Innovations
The company is not only innovative in its organizational structure but also in its technology.
The company has invented an automated growing food process through a helical structure that would
be placed in the center of a building. This structure employs an efficient robotic belt that moves each
row of plants one by one rather altogether. At the ground level, workers place seeds in pots and then
lifts elevate them to the top of the helix. Here, automatically they are placed on a belt that takes them
steadily back down to the ground, controlling the amount of sunlight they receive depending on their
age and size. By the time they reach the ground, the plants are ready to be harvested. To keep the
crops in sunlight as much as possible, the trays move more quickly when in the shade. Eventually,
LED-lights will be employed to complement solar exposure (Figure 7). Plantagon has also made
advancements in hydroponics by introducing pumice soil as a growing medium instead of relying
completely on water. Pumice, a volcanic rock that results from the cooling of lava in water, possesses
a unique porosity that absorbs nutrients and then channels them to plants. This may overcome the
common problem of tastelessness that hydroponically generated produce is notorious for, though both
methods provide similar levels of nutrition [66].
Figure 6.
The concept of “companization” by Plantagon. The model is described as a hybrid
system that combines two legally bound units: one of the units is a profit-driven company called
Plantagon International AB, and the other one is non-profitable association called Plantagon Non-profit
Association [
65
]. The “companization” aims to combine profit-driven commercial forces with non-profit
moral and ethically-oriented driving forces in one organization [
65
]. It is a blend between the top-down
action oriented commercial organization and the bottom-up, inclusive and democratic nonprofit
association. (Adapted from [65]).
Buildings 2018,8, 24 23 of 36
Figure 7.
A proposed vertical farm by Plantagon. It comprises a helix structure placed in the center of
a sphere-shape building and stretches vertically. The helix structure contains a robot belt that instead
of moving thousands of plants over the whole belt, it moves each raw of plants one by one. Seeds are
placed in pots on the belt at the ground floor level. Then, plants are elevated to the top by an elevator
and placed on the moving belt which takes them back to the ground, and by the time they reach the
ground floor, plants are ready to harvest. (Drawing by author).
Plantagon offers three approaches to vertical farming: façade farming, multifunctional farming,
and standalone farming [65].
The Plantawall Façade System
This approach proposes turning a building’s façade into a productive greenhouse. It specifically
suggests placing a six-meter-deep (20 ft) greenhouse at the perimeter where solar exposure is greatest.
Plants sit in trays that constantly move on parallel conveyor belts, obtaining maximum exposure to
natural light in the process. The PlantaWall façade system is based on a flexible modular structure that
can be attached to the whole facade or part of an existing structure. In addition to structural flexibility,
the façade system provides the benefit of soundproofing, supporting a healthy work environment,
and improving thermal insulation and shade. Furthermore, the system fosters a symbiotic relationship
that creates a healthy environment for everyone by transferring CO
2
from people to plants and O
2
from
plants to people. However, the façade system reduces the amount of natural light that can penetrate
deeply into a space [65].
Multi-Functional
In addition to farming, the multifunctional vertical farm incorporates functions such as office
space, hotel, and retail space as well as residential and educational uses.
Standalone
The standalone vertical farm is dedicated exclusively to the industrial production of food.
The company has produced two prototypes, a sphere for tropical climates and a half-moon shape for
temperate climates. The later prototype, named “Plantscraper” is a building that has been proposed
Buildings 2018,8, 24 24 of 36
in downtown Linköping, south of the Swedish capital of Stockholm (Figure 8). The purpose of this
structure has been to create a reference building that can be used as a model of vertical farming.
The “Plantscraper” is a 12-story, mixed-used tower that houses an indoor farm along the southern
façade (The PlantaWall), a farmers market at the ground floor and office spaces for proposed urban
farming research [
65
]. The renting of office space will provide supplemental income to the building.
It is estimated that the Plantscraper will produce between 300 and 500 metric tons of leafy greens,
particularly pak choi, a year. Pak choi, also known as celery cabbage, is a Chinese vegetable that
can be eaten raw or cooked [
65
]. This leafy green has been emphasized because Plantagon wants
to use this building as a model for Asian cities. In addition, the building will collect and reuse
all wastewater, with all pesticides, fertilizers, and soil pollution being automatically monitored
and controlled. Interestingly, Plantagon plans to integrate the vertical farm with the city’s civic
infrastructure, i.e., electricity, gas, water, and sewage [66].
Figure 8.
One of Plantagon’s prototype for the vertical farm. Seeds are planted in the first floor, then
carried to the top via elevators, and next moves down by the helix belt system. (Adapted from [65]).
3.5.4. La Tour Vivante
The French architecture firm Atelier SOA has proposed a 30-floor mixed-use vertical farm—Tour
Vivante (Living Tower)—that houses farming, residences, office spaces, restaurants, and retail.
The concept evokes the sense of a self-contained vertical neighborhood that enjoys autonomy and
reduces travel needs between the rural and the urban, by bringing together the activities of production
and consumption into one space [
67
]. People who live and work in the tower can enjoy proximity
to fresh, ripe, and preservative-free produce while the tower’s tenants provide a constant income
that supports the farms. It is also possible that residents of the tower could be employed in the
building to reduce travel times between home and work. Additionally, combining farming, housing,
and office spaces brings together the traditionally distant rural farming experience close to residents,
reconnecting them with nature. The tower’s architects explain that “the separation between city and
countryside, urban planning and natural areas, places of living, consumption, and production is
Buildings 2018,8, 24 25 of 36
increasingly problematic for sustainable land management
. . .
The concept of Tour Vivante aims to
combine agricultural production, housing and activities in a single system” [67].
The interweaving of these functions and activities aims to provide a symbiotic relationship
between the inhabitants and the farming environment. For example, food waste from restaurants
and residents will be collected and processed to be used as a liquid fertilizer to fruits and vegetables.
Similarly, the oxygen produced by plants will be channeled to tenants, while the carbon dioxide
produced by the tenants will be transferred to plants. Rainwater from the roof and the façades will
be collected, filtered, and used in the farm, and the waste generated by the farm and other functions
(housing, offices) will be collected and used to generate power for the tower [67].
Blackwater produced by the tower will be recycled and purified to feed and fertilize the plants.
The Tour Vivante also embraces renewable energy by employing two large wind turbines, as well as
photovoltaic panels, placed on the southern façade of the building and its roof. The tower will also be
constructed from recycled and recyclable materials. A thermal concrete shaft at the core of the building
will help to control solar gain and humidity in the building while facilitating natural ventilation
through the “chimney effect” and the application of a double skin façade. Overall, the tower explores
possibilities of blending architecture with agriculture, merging food production and consumption into
one place [67].
3.5.5. Harvest Green Tower
The city of Vancouver, British Columbia, Canada, expects to face rapid urban growth in the
coming decades that would result in substantial demands on food. Romses Architects has recently
proposed a multifunctional vertical farm in Vancouver in support of the City’s 2030 Challenge of
reducing carbon emissions. The project, named “Harvest Green Tower”, provides space for a mix of
uses including residences, offices, entertainment, retail, restaurants, and vertical farming that will
produce vegetables, herbs, fruits, fish, egg-laying chickens, goat cheese, and sheep dairy. The project
also connects well with the city’s public mass-transit system. The main sections of the tower are
described as follows [68].
Underground. A parking lot and shared car co-op
Street level. A grocery store, farmer’s market, restaurants, and a transit hub
Lower floors. A livestock grazing plain, bird habitat, goat cheese, and sheep dairy facility
Middle floors. A space for producing fruits, vegetables, and fish
Upper floors. Residential units
Tower’s top. A large rainwater cistern
The tower will harness renewable energy by installing rooftop mounted wind turbines on the
roof, photovoltaic glazing on the façade, a geothermal station underground, and bio-energy from the
compost of plants and animals. All of these combined factors provide the possibility of selling surplus
power back to the grid. Rainwater will be collected in a cistern atop the tower and used to irrigate
plants through the downward pull of gravity. The project was a winning entry in Vancouver’s 2030
Challenge given that it addressed climate change through the promotion of high-density mixed-use
developments in the urban core, thereby curtailing sprawl [68].
3.5.6. Skyfarm
Designed by architect Gordon Graff, the Skyfarm is a 59-floor vertical farm proposed for
downtown Toronto, Canada. This tower embraces the hydroponic method for growing food, using
an area totaling about 743,224 m
2
(8,000,000 ft
2
). It is predicted that the Skyfarm will produce
the equivalent of a thousand-acre rural farm, feeding about 35,000–50,000 people per year [
69
].
The building will be equipped with its biogas plant that contains an anaerobic digester to produce
methane from its waste, which is then burned to generate electricity. The system can also reclaim the
Buildings 2018,8, 24 26 of 36
waste and sewage by diverting it to the Skyfarm’s anaerobic digester to produce the methane necessary
to generate electricity. Furthermore, the liquid slurry extracted by the anaerobic digesters could be
used by rural farms as fertilizer [69].
3.5.7. Pyramid Farm
Architecture professors Eric Ellingsen and Dickson Despommier have proposed a self-sustaining
30-story “Pyramid Farm” to produce a wide variety of fruits and vegetables as well as fish and poultry
farm that will feed about 50,000 people annually. The project embraces a closed-loop agricultural
ecosystem where nearly every element of the farming process—including water and nutrients—is
recycled and re-used, minimizing waste drastically. The farm will include a heating and pressurization
system that splits sewage into water and carbon, fueling machinery and electrifying lighting. Overall,
the proposed farm will be efficient, as it will utilize only 10% of the water used in traditional farming
techniques and only 5% of the space of a traditional farm. Finally, the visual quality of the pyramid is
appealing and would fit well into an urban area [70].
3.5.8. Vertical Farm in Philippine
A recent visionary project proposed a vertical aeroponics farm that offers high yields of rice in the
Philippines; a country that faces food insecurity and lacks farmland. Rice is a particularly valuable
food not only in the Philippines but also across the globe, given that half of the world’s population
relies on rice as a major food source. Jin Ho Kim has proposed using aeroponics technology that uses
minimal water to grow rice compactly on a terraced vertical farm to be constructed by an array of
bamboo parallelograms. The project will create local jobs, supply local food, and lead to significant
savings in transportation, storage, refrigeration, and packaging, eventually incorporating spaces for
social gatherings and children [70,71].
4. Discussion: Opportunities and Challenges
Vertical farming represents a proactive thinking approach that aims to ensure the sustainability
of cities by addressing the issue of food security. The urban population already faces food shortages,
and food prices are skyrocketing due to increases in oil prices, shortages of water and the diminishment
of other agricultural resources. The current practices of supplying food to urban areas suffer from
environmental and economic problems, such as the inefficient practice of transporting food great
distances. As an answer to these problems, the vertical farm will grow food efficiently and sustainably
by saving energy, water, and fossil fuels, reducing toxins and restoring ecosystems, as well as
providing new opportunities for employment. We have seen the rapid growth of modest-scale
vertical farming, and these projects have provided excellent examples of adaptive reuse of vacant
industrials spaces [7276].
Therefore, the vertical farm may offer opportunities in the three pillars of sustainability:
environment, society, and economy (Table 6). It can offer a sustainable food-production model
that supplies crop year-round with no interruption due to climate change, season, or adverse natural
events (e.g., hurricane, drought, and flood). It has also the potential to provide greater yield per space
unit—the ratio is 1:4–1:6, depending on the type of crop [
77
,
78
]. Further, the high-tech cultivation
methods of the vertical farm reduce demand on potable water. They are often efficient in irrigating
plants, by targeting plant roots and reducing evaporation [
79
]. They may also recycle wastewater (grey,
even black water) and harness rainwater. When fish farms are integrated, fish removes waste (esp. fish
filet). The vertical farm can also produce energy by burning methane from compost. For example,
the Plant Vertical Farm in Chicago and the Republic of South Korea VF factory convert waste to
energy [80,81].
Buildings 2018,8, 24 27 of 36
Table 6. Key sustainable benefits of the vertical farm.
# Benefit Environmental Social Economic
1Reducing food-miles
(travel distances) Reducing air pollution
Improving air quality
improves environmental
and people’s health.
Customers receive
“fresher” local food
Reduce energy, packaging,
and fuel to transport food
2
Reducing water
consumption for food
production by using
high-tech irrigation systems
and recycling methods
Reducing surface water
run off of traditional farms
Making potable water
available to more people Reduce costs
3 Recycling organic waste Save the environment by
reducing needed land fills
Improve food quality and
subsequently consumers’
health Turn waste into asset
4 Creating local jobs
People do not have to
commute to work and
hence will decrease
ecological footprint
Create a local community
of workers and social
networks with farmers
Benefit local people
economically
5Reduced fertilizers,
herbicides, and pesticides Improve the
environmental well-being
Improve food quality
and subsequently
consumers’ health Decrease costs
6 Improve productivity Needs less space
Reduce redundant,
repetitive work,
and save time to do
productive and socially
rewarding activities
Offer greater yields
7
Avoid crop losses due to
floods, droughts, hurricane,
over exposure to sun, and
seasonal changes
Decrease environmental
damage and cleanups of
farms after damage Improve food security Avoiding economic loss
8Control product/produce
regardless to seasons Produce regarding season
Increase accessibility
year-round and improve
respond to population
demand
Fuel economic activities
year-round
9 Using renewable energy Reducing fossil fuel Improve air quality Reduce costs
10
Bringing nature closer to city
Increase bio-diversity Improve health, reduce
stress and enhance
psychological well-being Create jobs in the city
11 Promoting high-tech and
green industry
“green technology”
reduce harm and improve
environmental
performance
Encourage higher
education and generate
skilled workers
Provides new jobs in
engineering, biochemistry,
biotechnology,
construction and
maintenance, and research
and development
12 Reducing the activities of
traditional farming Preserving natural
ecological system Improve health of citizens Saving money
required to correct
environmental damage
13 Repurposing dilapidated
buildings
Enhance the
environment. Remove eye
sores and stigma from
neighborhoods
Create opportunities for
social interaction Revive economy
When compared to traditional farming, the vertical farm may reduce the need for fossil fuel
required for tractors, plows, or shipping. Traditional farming uses lots of fossil fuel; for example,
conventional farming in North America consumes 20% of fossil fuel due to plowing, seeding,
harvesting, fertilizing and so on [
82
,
83
]. The vertical farm can also reduce food travel distance
(food-miles) by promoting “local for local” life style, i.e., distances between food production and
consumption are minimized [
84
86
]. As mentioned earlier, in conventional farming, food travels on
Buildings 2018,8, 24 28 of 36
average 1500 miles. Further, the vertical farm eliminates the need of packing agricultural crops for
long-distance transportation [6,87,88].
Indoor farming is immune to weather change, which affects traditional farming by changing
temperature, water supply, and photo intensity. These factors often reduce produce yield; for example,
droughts destroy crops every year worldwide [
88
,
89
]. As such, the vertical farm will be important
for food security especially as climate change threatens our cities. As mentioned earlier, Gotham
Greens was the only fresh food supplier in New York during the Sandy Hurricane. Additional benefit
of the vertical farm is providing an ideal growth environment for each plant that improves crop
yield [
62
,
73
]. Advances in technologies, for example, the LED lighting, promises to increase yields as
LED emits programmed wavelength of light for optimal photosynthesis of different types of crops.
Luckily, the prices of these technologies are dropping [
74
]. The vertical farm provides an environment
almost free of invasive pest species [
90
]. It also reduces, and possibly eliminates the use of mineral
fertilizers, herbicides and pesticides, and nitrogen (N) and phosphorous (P), which have been causing
environmental degradation by polluting surface water and groundwater [9193].
The vertical farm can assist in cooling the environment, sequestering CO
2
, reducing the Urban
Heat Island (UHI) effect, and combating climate change [
94
,
95
]. As such, it can help in reducing energy
needed to cool indoor spaces in summer time and reduce carbon dioxide emission [
96
98
]. Further,
the vertical farm can help in absorbing noise since vegetation reduces sound reflection. Vegetation and
soil can function together as sound insulator [
97
,
99
]. When rooftop farming or green roofs are also
applied, noise could be lowered further by absorbing higher frequency noise produced by auto traffic,
machineries, and airplanes [99].
The vertical farm may also provide socio-economic benefits by offering employment
opportunities [
100
]. Building a vertical farm requires a multi-disciplinary team of architects, engineers,
scientists, farmers, horticulturists, environmentalists, marketers, and economists. For example,
industrial, mechanical and electrical engineers will be needed to design water recycling systems,
lighting systems, heating, ventilation and air conditioning (HVAC) systems, seed and plant growth
monitoring and harvesting systems. Computer experts will be needed to build databases and software
applications. As such, the vertical farm offers new exciting careers in biochemistry, biotechnology,
construction, maintenance, marketing, engineering, and research and development opportunities for
improving the involved technologies [
100
102
]. Further, robotics and software engineers could also be
needed. Moreover, a vertical farm may include grocery stores and engage distribution centers, which
provide additional work opportunities [68,103].
Further, vertical farming is likely to create new social networks and communities that forge new
friendship in the workspace and beyond, among producers, farmers, and consumers [
93
]. In addition,
vertical farmers may enjoy selling their produce directly to customers and develop friendships [
104
].
Vertical farms could have an important educational role in informing about plants and produce by
bringing farming activities closer to city dwellers. For example, Gotham Greens in New York frequently
invites visitors and students to their vertical farm and holds educational sessions [105].
Our health is directly impacted by the “freshness” and wholesomeness of food we consume and
the vertical farm intends to supply quality, local organic food [
58
,
89
]. It could help consequently to
reduce or stop the transmission of harmful infectious diseases for currently much produced food by
conventional agriculture is polluted and carry bacterial diseases that endanger the lives of millions of
inhabitants. That is, since the vertical farm product is not soil-based, it is likely to be not affected by
polluted soil or irrigation water. Further, vertical farm’s crops are rich in nutrients [
106
,
107
]. Moreover,
being close to nature helps to reduce stress and has positive influence on mental health.
Notwithstanding the promising future and large potential benefits, challenges and barriers in the
path to the vertical farm implementation should be noted. Research has highlighted social resistance,
where masses of people do not accept the alteration of traditional farming for it is the natural way to
grow food [
77
,
89
,
94
,
99
]. Importantly, the core argument against vertical farming is that growing food
indoors requires more energy, effort, and resources than traditional farming [
86
,
98
,
100
]. That is, “It is
Buildings 2018,8, 24 29 of 36
much more expensive, of course, to build a vertical greenhouse than to build a normal greenhouse” [
72
].
Despommier acknowledges that the costs of implementing vertical farms are high, particularly the
start-up costs, and he calls on the government to provide the seed money to fund these projects.
Apparently, to raise the required investment capital is a challenge. In short, in order for the vertical
farm to be sustainable, it must be profitable.
Further, central cities are ideal locations for vertical farms for enjoying proximity to dense
population and major retail outlets [
69
]. However, the issue of affordability is salient in central cities
where land and space are expensive. For example, central areas in major cities in Hong Kong, Australia
(e.g., Melbourne, Sydney), United Kingdom (e.g., London) have very expensive real estate, which
presents an economic difficulty at the commercial scale [
107
]. However, some major cities such as
New York and Chicago have sizable stocks of vacant older properties that could be repurposed into
vertical farming. This has happened in projects such as The Pant in Chicago, IL and AeroFarms in
Newark, NJ [49,72].
Overall, residential, retail, office, and commercial uses of high-rises continue to be more profitable
than that by agricultural activities [
95
]. It seems that increasing the productivity of the vertical farm
is the prime factor to make it prevail in the future. “If the yield per hectare for indoor farming
is much higher than rural outdoor farming, perhaps as much as up to 50 times, this factor will
eventually outweigh the initial cost of land acquisition
. . .
and assuming 50-fold improved productivity,
the break-even point may well be an estimated 6–7 years” [
106
] (p. 295). Such production will likely
to offset the startup costs including expensive land or rent. Another drawback of the vertical farm is
inability to produce all types of crops. In fact, current vertical farms produce limited crops such as
lettuce, tomatoes, strawberries, and to less extent, grape, and soy products. Also, produced quantities
are too small. Martin’s research indicates an imbalance between vertical farms’ production and their
catchment areas, where many of population reside in these areas are underserve. They found that in
the near future, urban food will continue to come from distant rural areas [98,107].
Further, due to economic reasons, most vertical farms produce and then distribute leafy greens to
restaurants, and local residents remain not the prime client. In the same manner, low-value agricultural
commodities such as wheat continue to be economically unviable. Therefore, the current product of
vertical farms is limited in scope and quantities. Overall, production volumes of vertical farms are
small, particularly when compared to “limitless” acres of traditional farming. Further, scaling up
vertical farming could be costly and complex [86,108,109].
Another limitation is that current renewable energy sources, such as photovoltaics and wind
turbine, produce little energy that would make it difficult not to rely on the city grid. It is only the
plants at the building’s perimeter and on the top level that could benefit from solar radiation [
34
,
109
].
In this regard, it is important to employ rotatable stacked arrays of plants inside each floor of a high-rise
enclosure so that plants receive maximum natural light [93].
Consequently, until now, no multi-story vertical farm tower has been built, and despite copious
attempts to make this a reality, the concept of the vertical farm tower remains on the drawing board.
Despommier hints at a solution by stating that “High-rise food-producing buildings will succeed only
if they function by mimicking ecological process, namely by safely and efficiently re-cycling everything
organic, and recycling water from human waste disposal plants, turning it back into drinking water” [
4
]
(p. 121).
5. Conclusions
A plethora of research and pioneering projects has demonstrated the potential of vertical farming
at the pilot scale, prototypes and at the production level. The vertical farm has the potential to play
a critical role in the sustainability of food in urban areas. This is most important as we project
into the future when urban population will increase significantly. Vertical farming has various
advantages over rural farming, observed within the three pillars of sustainability: environmental,
social, and economic. New high-tech cultivation methods, including hydroponics, aeropnics and
Buildings 2018,8, 24 30 of 36
aquaponics, largely challenge the need for soil-based farming for a range of crops. Advancements
in greenhouse and supporting technologies such as multi-racking mechanized systems, recycling
systems, LED lighting, solar power, wind power, storage batteries, drones as well as computing
power, software applications, databases and The Internet of Things are likely to coalesce into efficient
production systems in the near future. Increasingly, there is a need for interdisciplinary research and
collaboration that promote collective thinking among the various disciplines involved in creating
vertical farms [110114].
Perhaps, in the distant future, there is the prospect of developing fully automated vertical farms.
And hypothetically, if vertical farms were integrated in the city, they will be able to supply food for
the entire population. However, there is still a need for more developments that scale up projects so
that the economic and commercial feasibility and return on investment (ROI) are offered at best rates.
As such, there is a need for research that accurately assesses the ROI of various types and sizes of
vertical farms. There is a need to investigate the full life-cycle analysis (LCA) and the number of years
to reach parity with a traditional farm [109,115,116].
The success of the vertical farm will depend not only on innovation in technologies but also on
local conditions including demand on certain produce by population, availability of labors, and farming
conditions. An effective organizational structure and sound leadership are also important factors.
Creativity, stewardship, and inventiveness are critical ingredients for companies that venture into new
businesses such as vertical farming. In a globalized world, competition is stiff, but the first to succeed
may gain a competitive edge [
99
,
108
,
115
]. As such, robust and resilient business models are needed
in a world characterized by increasing complexity, nonlinearity, and “glocal” exchanges of goods.
According to Copenhagen Institute for Futures Studies, Instituttet for Fremtidsforskning “Tomorrow’s
innovative leader isn’t necessarily the person in front with innovative ideas, but the one who discovers
the front-runners and harvests their ideas to cultivate and nourish the innovative environment in his
organization” [
74
]. Nevertheless, interest in vertical farming will increase as climate change prevails
further and available arable land per capita declines [117].
One more serious obstacle remains; the increasing populations of developing countries. Do these
countries possess the required technologies and technical expertise to implement the vertical farm?
These countries are largely poor. Can we make the products of the vertical farm affordable to the
poor? Furthermore, many of these poor populations live in slums, in food deserts, away from modern
life. How can we make the produce of vertical farms accessible to slum populations? Ultimately,
the effectiveness of vertical farming will depend on various local factors, including the demand and
supply of food, urban populations and their density, technological development, culture and eating
habits, water and energy supply, as well as weather conditions.
6. Future Research
Vertical farming is growing rapidly, and this research barely scratches the surface of long and
complex endeavor. The examined projects offer catalysts to further developments. Future studies
may examine other projects including, but not limited to, Green Sense Farms (Portage, Indiana and
Shenzhen, China), AeroFarms (Newark, NJ, USA), Metropolis Farms (Philadelphia, PA, USA), Plenty
(San Francisco, CA, USA) VerticalHarvest (Jackson, WY, USA), Lufa Farms (Montreal, QC, Canada),
VertiCrop
TM
(Vancouver, BC, Canada), and a new un-named project in Suwon, South Korea. Also,
future research may examine specialized technologies and methods for various indoor farming systems.
For example, hydroponic systems offer multiple methods, including Nutrient Film Technique (NFT),
Wick System, Water Culture, Ebb and Flow (Flood and Drain), Drip Feed System and Aeroponic
Systems. Further, there is a need for conducting quantitative research that gives accurate assessments
of the benefits and shortcomings of various types of vertical farms. Importantly, future research should
examine the issue of affordability of advanced equipment of vertical farming to developing countries.
Researchers should invent, advance, and further develop local farming techniques to make vertical
farm projects feasible in these countries. For example, they may invent recycling methods that reduce
Buildings 2018,8, 24 31 of 36
reliance on water, design local systems by capturing rainwater, and may capitalize on local solar power
for providing natural light and energy.
Acknowledgments:
The author would like to thank the journal’s reviewers for providing helpful comments,
and the staff for careful and professional work.
Conflicts of Interest: The author declares no conflict of interest.
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... According to Al-Kodmany (2018), to respond to the aforementioned question, why vertical farms? It is significant to explore the following trends [17]; ...
... According to demographers, urban populations are expected to multiply in the future decades. According to experts in land use (such as agronomists, ecologists, and geologists) [17]. Even in industrialized nations where fresh food supplies are scarce areas referred to as "food deserts" figuratively, food security is a significant concern. ...
... Closed-loop farms would remove the need for toxic herbicides and pesticides while boosting nutrition and food value at the same time [33]. VF can be classified into three methods of production: hydroponics, aeroponics, and aquaponics [17]. ...
... At the same time, the FAO states that the use of chemical fertilizers has increased by 40% since 2000 and the total of fertilizers used in 2018 was 188 million tons. Simultaneously, the world is facing challenges posed by climate change and the inability to exploit further arable land due to erosion or adverse weather conditions, while about 80% of the available arable land has already been utilized [6,20,157]. Despommier [158] characteristically stated that if farming techniques continue as they are, in 2050 arable land the size of Brazil (1 billion ha) will be necessary to meet global food demand. ...
... In most cases, crops travel several km and need to be stored in special packages and often refrigerated in order to be preserved until they reach their destination. Especially in cases where the weather does not favor the cultivation or food is not produced locally, crops are imported from other countries, thus greatly increasing the miles they need to travel from farm till fork [157]. In addition to the fuels consumed in traditional farming methods for agricultural operations, food transport includes trucks, ships and airplanes, which consume large amounts of fuels both for food transportation and preservation via cooling methods [6,20]. ...
... Labrador et al. [165] mentioned batteries' use for the storage of excess electricity generated by PV panels, which could consequently be distributed to other VFs through fuzzy logic control, to improve power consumption and reduce the carbon footprint. Al-Kodmany [157] mentioned in his work already existing CEA systems that use biogas produced from organic waste for heating, CO 2 enrichment and electricity production, while plant residues are recycled by biogas facilities. Other CEAs implement systems for recycling, reusing and composting both the water used by the building they are located at and the plant residues, thus contributing significantly to the discharge of the city's recycling system [146]. ...
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The rapidly growing population and increasing urbanization have created the need to produce more food and transport it safely to urban areas where the majority of global consumers live. Open-field agriculture and food distribution systems have a lot of food waste, and, in parallel, the largest percentage of available arable land is already occupied. In most cases, food produced by compatible agricultural methods needs to be frozen and travel several miles until it reaches the consumer, with high amounts of greenhouse gas (GHG) emissions produced by this process, making it an unsustainable method with huge amounts of CO2 emissions related with fresh food products. This research contains an extensive literature review based on 165 international publications (from 2006–2022) describing and analyzing the efficiency and impact of controlled-environment agriculture (CEA) methods, and more precisely, greenhouses (GHs) and vertical farms (VFs), in the environmental footprint of food production and consumption. Based on various publications, we could draw the conclusion that VFs could highly influence a greener transition to the sustainability of urban consumption with reduced CO2 emissions sourcing from food transportation and limited post-harvest processes. However, there is a significant demand for further energy efficiency, specifically when it comes to artificial lighting operations inside VFs. A large-scale implementation of VFs that operate with renewable energy sources (RES) could lead to significant urban decarbonization by providing the opportunity for integrated energy–food nexus systems. Under this direction, VFs could optimize the way that cities interact with meeting the food and energy demand in densely urbanized areas.
... Indoor farming was originally developed from conventional greenhouse farming systems; today, it has deviated radically, and comprises many variations. Al-Kodmany [11] described the urban smart farm as a system that is often called 'vertical farming', which allows food to be grown under smart climate-controlled indoor environments by using technological innovation. ...
... Critics of USF point towards its low practicality. However, the outdoor open environment and conditions are often more uncontrollable than those inside high-performing buildings [11]. ...
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African cities are growing rapidly into inefficient, unsustainable, resource-starved ecosystems that negatively affect the local economy and food production. Food as a critical resource needs to be produced and managed more efficiently by local communities in the urban area. Urban smart farming (USF) has emerged as an important mechanism to address these challenges to achieve sustainable, resilient, and inclusive cities. USF has the potential to be the industry 4.0 green revolution in agriculture, which embodies innovative digital technologies. However, it is unclear how local African communities and key stakeholders perceive this novel solution and if they are willing to engage in its uptake. This study examines the relationship between the perceived benefits and challenges of USF and the willingness of local African communities to actively participate in USF projects as a potential mechanism to improve local economy and food production. To assess this relationship, a causal model was developed. In this causal model, the local economy and food production were defined as dependent variables. The conceptualized model and the inherent causality between the constructs were validated through a survey administered among African cities’ residents. The results of structural equation modelling indicate a significant positive impact of perceived benefits of USF as well as the willingness of African communities to engage in this technology on local economy and food production. Only minimal adverse effects of the perceived challenges of USF on the local economy and food production have been found. The study concludes that the benefits and willingness of local communities are the key drivers for implementing urban smart farms in African metropolitans. Therefore, it is recommended to focus on the benefits and the motivation of local communities in African cities where USF shall be further developed, rather than on the barriers. The validated causal model can be used as a framework to facilitate the adoption of USF in Africa and consequently enhance the local economy and food production in African cities.
... This is a main factor that creates barriers to increased technology uptake [38,39]. Indoor UA farms have been found to cause emissions ranging from 4.2 to 26.5 kg CO 2 e to produce a kg of leafy green plants and are highly influenced by the installed technology [15,30,[40][41][42]. In most cases the major contributor was electricity, highlighting the need for extensive energy efficiency modeling of IVF equipment and considering alternative renewable electricity sources depending on the location [25,29,43,44]. ...
... The latter 26.5 kg CO 2 e/kg value was found for a controlled environment greenhouse with heating demand in winter, whereas the lower results represent a system without climate control and lighting [24]. Due to the urban location, combination of technologies, system boundary and lack of standardization for measurement of functional units in fresh or dry weight, it can be difficult to make meaningful comparisons [40]. ...
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Indoor Vertical Farms (IVF) can contribute to urban circular food systems by reducing food waste and increasing resource use efficiency. They are also known for high energy consumption but could potentially be improved by integration with buildings. Here, we aim to quantify the environmental performance of a prospective building-integrated urban farm. We performed a Life Cycle Assessment for a unit installed in a university campus in Portugal, producing broccoli microgreens for salads. This technology integrates IVF, product processing and Internet of Things with unused space. Its environmental performance was analyzed using two supply scenarios and a renewable energy variation was applied to each scenario. Results show that the IVF system produces 7.5 kg of microgreens daily with a global warming potential of 18.6 kg CO2e/kg in the case of supply direct on campus, or 22.2 kg CO2e/kg in the case of supply off campus to retailers within a 10-km radius. Consistently in both scenarios, electricity contributed the highest emission, with 10.03 kg CO2e/kg, followed by seeds, with 4.04 kg CO2e/kg. The additional use of photovoltaic electricity yields a reduction of emissions by 32%; an improvement of approximately 16% was found for most environmental categories. A shortened supply chain, coupled with renewable electricity production, can contribute significantly to the environmental performance of building-integrated IVF.
... The Babylonian Hanging Gardens were constructed in 600 BC based on a similar concept (Container Farms, 2021). Gilbert Ellis Bailey coined the term "vertical farming" in his book Vertical Farming in 1915 and claimed that VF can provide many economic and environmental benefits (Al-Kodmany, 2018;Jasrotia & Chandra, 2016). Recently, Dickson Despommier defined VF as the combination of plant and animal life in skyscrapers for commercial purposes, grown using hydroponic and aerodynamic technologies (Despommier, 2010). ...
... Starting to attract significant attention. (Al-Kodmany, 2018;Cooper, 2013;Gupta & Ganapuram, 2019) Aquaponics . A bio-system that creates a symbiotic relationship. . ...
Can skyscrapers survive after COVID-19? Can the idea of integrating vertical farming (VF) into vertical architecture support the environmental, economic, and social issues in the post-pandemic era? Answering these questions is the main objective of this study. Therefore, it explores a) the impact of the pandemic on the built environment, especially skyscrapers; b) the challenges facing the survival of skyscrapers; c) the design parameters and main components of VF; and d) the expected feasibility of integrating VF into vertical architecture to reduce the effects of the pandemic. The research concludes that the skyscraper-integrated vertical farming (SIVF) paradigm can create a closed ecosystem that preserves the environment by a) supporting food security, b) improving indoor environmental quality, c) enhancing psychological and physical health, d) saving energy, e) reducing greenhouse gas emissions and releasing oxygen, and f) supporting the local economy. Consequently, the SIVF paradigm can inaugurate an innovative approach that provides insights into new research trends and discoveries. However, further constraints in the adoption of SIVF should be addressed, and collaborations between researchers and multidisciplinary experts must be created to achieve suitable solutions. KEYWORDS COVID-19; skyscrapers; vertical architecture; vertical farming; food security; skyscraper-integrated vertical farming
... The fact that vertical garden enterprises are located in the city reduces transportation costs considerably and thus, both carbon emission and food losses during transportation can be reduced considerably [6]. One of the most important contributions of vertical garden to supply food, it provides production opportunities throughout the year [7]. Tomato is one of the vegetables with the highest production in the world and its production is increasing all over the world [8]. ...
... The fact that vertical garden enterprises are located in the city reduces transportation costs considerably and thus, both carbon emission and food losses during transportation can be reduced considerably [6]. One of the most important contributions of vertical garden to supply food, it provides production opportunities throughout the year [7]. Tomato is one of the vegetables with the highest production in the world and its production is increasing all over the world [8]. ...
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One of the most important realities of today and the future is that the number of people living in urban areas across the world is greater than that of rural areas. Implementing measures at the city level that challenge current food systems and improve urban sustainability are time sensitive and necessary, and has led to a search for sustainable and alternative methods of urban food production. Urban agriculture can be done in open and closed areas including vertical garden. The field experiment was conducted under vertical garden at Daye town, in sidama region, Ethiopia in 2022 cropping season to determine the optimum vertical and horizontal distances for tomato production under vertical garden. The experiment was laid out in Randomized Complete Block Design with factorial arrangement with three replications and consisted two vertical distances (40 cm and 50 cm) to ward vertical and two horizontal distances (50cm, and 60cm) with Total of 4 treatments combination. Interaction effects influenced days for all phonological parameters, growth, yield and yield components. 40 cm toward vertical with 60 cm toward horizontal spacing exhibited the highest tomato fruit yield (68.73 kg per structure). The highest marginal rate of return (MRR%), 5592.9 was recorded from 40 cm toward vertical with 60 cm toward horizontal spacing under this vertical garden on tomato production. Given the fact that fruit yield performance between the two vertical spacing in combinations two horizontal spacing, 40 cm toward vertical with 60 cm toward horizontal spacing is recommended for tomato production under vertical garden of Daye town and similar agro-ecologies in the midlands towns of Ethiopia.
... There is an urgent need to use technologies that allow for space optimization, water use efficiency, and input management to improve fruit and vegetable production [16]. By adopting vertical gardens, the available vertical space can be utilized to increase the number of plants grown per unit area [17]. Vertical gardens are a popular and preferred method for rooftop, indoor, balcony, and other forms of urban agriculture, with high productivity of vegetables at a lower cost [18]. ...
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The wonder multistorey garden (WMSG) is an innovative vertical farming system tailored for urban settings that can be constrained by the irrigation regime, and by types and levels of fertilizer application. This study evaluated the effects of applying NPK fertilizer and black soldier fly frass fertilizer (BSFFF) under different irrigation regimes on the growth, yield, and pest infestation of kale (Brassica oleracea) and Swiss chard (Beta vulgaris). The fertilizers were applied at rates equivalent to 371 kg N ha −1. For each crop, the BSFFF or NPK was applied to supply 100% of the N required (100% BSFFF), and then a combination of BSFFF and NPK was applied so that each fertilizer supplied 50% of the N required (50% BSFFF + 50% NPK). Crops' water requirements were provided using three irrigation regimes: daily, every two days, and every three days. The control treatment was not amended with any fertilizer, while water was provided ad libitum. The results revealed that the irrigation regime significantly affected the leaf production of both vegetables. Irrigation regimes significantly influenced kale plant height, where plants provided with water daily achieved the highest average heights of 20 cm, 46 cm, and 54 cm at 14, 28, and 42 days after transplanting (DAT), respectively. Furthermore, the application of 100% BSFFF produced kale with significantly higher plant heights (55 cm) and number of leaves (9.9 leaves) at 42 DAT compared to other treatments. The interaction between irrigation regimes and fertilizer significantly influenced kale height at 14 DAT and 42 DAT. Use of daily irrigation regime and 100% BSFFF produced the tallest kale plants of 59 cm at 42 DAT. Application of 50% BSFFF + 50% NPK or 100% BSFFF with daily irrigation achieved the highest values of kale and Swiss chard leaf chlorophyll concentration, recorded at 42 DAT. Fertilizer application significantly affected pest population, with the lowest pest infestation being recorded from kale and Swiss chard grown in soil amended with BSFFF. The application of 100% BSFFF or NPK, together with daily irrigation, significantly increased the fresh shoot weight and leaf dry matter of kale and Swiss chard, as compared with the control. The fresh shoot yields of kale and Swiss chard achieved through using a combination of 100% BSFFF and daily irrigation were 14-69% and 13-56% higher than those of NPK, respectively. The same treatment combination also produced kales and Swiss chard with 8-73% and 16-81% higher leaf dry matter compared to NPK, respectively. It was noted that soil amendment with BSFFF maintained higher values of kale (41-50%) and Swiss chard (33-49%) leaf dry matter compared with NPK treatments, during periods of water stress. Our study has demonstrated the high potential of single (100% BSFFF) or combined applications of BSFFF (50% BSFFF + 50% NPK) with a daily irrigation regime to improve the growth, yield, and pest management in Swiss chard and kale under vertical farming. Our study advocates for the scaling of WMSG and BSFFF for sustainable food systems in urban settings. Citation: Abiya, A.A.; Kupesa, D.M.; Beesigamukama, D.; Kassie, M.; Mureithi, D.; Thairu, D.; Wesonga, J.; Tanga, C.M.; Niassy, S. Agronomic Performance of Kale (Brassica oleracea) and Swiss Chard
... A plant factory is a closed plant production system that aims to achieve high-precision control of plant growth environment and high crop yield (Avgoustaki and Xydis, 2020). Plant factory can avoid the impact of outdoor extreme weather conditions on plant growth (Al-Kodmany, 2018). Light-emitting diode (LED) is an indispensable lighting system that can provide different light quality, light intensity, and photoperiod to control plant growth. ...
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Pea sprouts have rich nutrition and are considered good for heart health. In this study, the kaspa peas and black-eyed peas were chosen to clarify the effect of different LED spectral combinations on the growth, yield, and nutritional quality of pea sprouts under long photoperiod (22 h light/2 h dark). The results showed that the two pea varieties responded differently to light spectral combinations. Black-eyed pea sprouts had higher plant height, fresh weight per plant, dry weight per plant, soluble sugar content, and lower malondialdehyde (MDA) content than kaspa peas under the same light treatment. Compared with white light, red-to-blue ratio of 2:1 significantly increased peroxidase (POD) and superoxide dismutase (SOD) activity, soluble sugar and soluble protein content of kaspa pea sprouts, and decreased MDA content of black-eyed pea sprouts. Blue light was negatively correlated with the plant height of pea sprouts and positively correlated with SOD activity, vitamin C, soluble sugar, and soluble protein content. Antioxidant capacity, yield, and nutritional quality of black-eyed pea sprouts were higher than those of kaspa pea sprouts under the same light treatment. Blue light improved the nutritional quality of pea sprouts. Compared with other light treatments, the red-to-blue ratio of 2:1 was more conducive to improving the antioxidant capacity and nutritional quality of pea sprouts under long photoperiod.
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This paper examines recent sustainable tall buildings in the Global South, mainly in the Middle East and China. These buildings are redefining how architects, engineers, and planners view skyscrapers, creating a new building typology in regards to function, ecology, technology, and user comfort, in the process. These "futuristic" buildings are setting new social, spatial, and environmental standards, setting a milestone in ecologically friendly architecture. Most of the reviewed projects in this paper have achieved national and international recognition from architectural and planning organizations. They represent the most recent work in the field and have exerted a profound impact on the architectural profession. This paper also summarizes the key lessons that sustainable tall buildings have brought to the field, highlighting the role of breakthrough technologies in enhancing the efficient performance and sustainability of future tall buildings. © 2016 Archnet-IJAR, International Journal of Architectural Research.
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Agriculture faces huge challenges regarding sustainable use of soils and its sustainability performance in general. There are three different approaches to sustainable agricultural production commonly proposed, namely intensification, agro-ecological approaches and high-tech industrial approaches. Often, some propose that only agro-ecological approaches are truly sustainable options, with particular benefits for soil protection, while others argue that intensification or high-tech performs better through land sparing. In this viewpoint, we scrutinize the notion of “sustainable agricultural production” and the role these approaches may play for such, in particular addressing the controversy of “naturalness” versus “artificiality” in production systems. Consumers often perceive agriculture as “natural”, but agriculture today thrives always on strong human intervention. We posit that agriculture is linked to soils and natural processes, but that this provides little guidance on what sustainable agriculture should be. Being “natural” need not be an aspect of being sustainable. If it is, arguments for this need to be provided. Furthermore, revealed consumer preferences may much less frequently posit being “natural” as a central criterion for food consumed than usually assumed. By all this, we do not want to promote any of those three approaches uncritically. We rather argue for enlarging the option space for sustainable agriculture in an unprejudiced way.