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The food provisioning of European cities depends on the global food supply system. However, both economic crises, environmental pressure and climate change effects represent a risk for food chain stability. Urban agriculture (UA) increases the self-sufficiency and resiliency of cities and is able to deliver positive environmental and social benefits. However, its efficacy depends on several variables, including the type of UA and the geographical location of the city. This paper analyses ReFarmers’ pilot farm, a vertical high-yield hydroponic croft located in the urban area of Lyon, France, from a life cycle perspective. The results show that the hydroponic farm performs better than cultivations in heated greenhouses, and similarly to conventional open field farms. Moreover, the source of the electricity input is a determinant factor that, if carbon neutral (e.g. wind energy) allows vertical hydroponic production to outperform the two conventional types of agriculture.
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2212-8271 © 201 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
Peer-review under responsibility of the scientific committee of the 25th CIRP Life Cycle Engineering (LCE) Conference
doi: 10.1016/j.procir.2017.11.048
Procedia CIRP 69 ( 2018 ) 540 545
25th CIRP Life Cycle Engineering (LCE) Conference, 30 April – 2 May 2018, Copenhagen, Denmark
Environmental impacts of urban hydroponics in Europe: a case study in
Daina Romeoa, Eldbjørg Blikra Veaa, Marianne Thomsena*
aDepartment of Environmental Science, Aarhus University, Frederiksborgvej 399, Postboks 358, DK-4000 Roskilde, Denmark
* Corresponding author. Tel.: +45 8715 8602; fax: +45 8715 5021. E-mail address:
The food provisioning of European cities depends on the global food supply system. However, both economic crises, environmental pressure
and climate change effects represent a risk for food chain stability. Urban agriculture (UA) increases the self-sufficiency and resiliency of cities
and is able to deliver positive environmental and social benefits. However, its efficacy depends on several variables, including the type of UA
and the geographical location of the city. This paper analyses ReFarmers’ pilot farm, a vertical high-yield hydroponic croft located in the urban
area of Lyon, France, from a life cycle perspective. The results show that the hydroponic farm performs better than cultivations in heated
greenhouses, and similarly to conventional open field farms. Moreover, the source of the electricity input is a determinant factor that, if carbon
neutral (e.g. wind energy) allows vertical hydroponic production to outperform the two conventional types of agriculture.
© 2017 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the scientific committee of the 25th CIRP Life Cycle Engineering (LCE) Conference.
Keywords: Life Cycle Assessment; Urban agriculture; Hydroponics
1. Introduction
The urban population in Europe has been growing at a
constant rate in the last 50 years, and is expected to reach 80%
of the total European population by 2050 [1]. This represents a
challenge for food provisioning, since cities are not able to
internally satisfy it [2]. Hence, the import of goods is
necessary to meet the food demand of urban citizens, which
has caused an increased dependency on the global food
production and supply system. Such a reliance on external
inputs represents a vulnerability when major political or
economic disruptions occur, and it can often be the leading
cause of such instabilities [3, 4]. The inequality in food
distribution represents an additional risk, worsen by the
increasing urban poverty [5, 6].
Adding on to the local challenges for food provisioning, the
global food supply chain is also vulnerable to big-scale
changes. In fact, climate change will put food security at risk
on several levels, for example by reducing yields and land
suitability, and by increasing frequency and severity of
extreme weather events [7]. Satisfying the demand of
fertilisers is another environmental challenge of food
production, given that mineral fertilisers are a non-renewable
resource that is being consumed at an increasing rate [8].
In addition to being vulnerable to disruptions, the food
system is also responsible of environmental degradation [9];
considering the environmental impacts generated by the final
consumptions of the European Union, the production and
distribution of foodstuff accounts for 30% of the impacts on
climate change, 33% of the impacts on ecotoxicity and 60% of
the impacts on eutrophication [10].
Urban agriculture (UA) has been proposed as a practice to
respond to the challenges presented above, and produce
positive environmental, economic and social effects, such as
shortening the food supply chain, reducing the emissions of
greenhouse gasses, microclimate improvement, improved
water management, improved diet-related health, and stress
reduction[3, 11–15]. Smit and Nasr [16] pointed out that urban
© 201 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
Peer-review under responsibility of the scientifi c committee of the 25th CIRP Life Cycle Engineering (LCE) Conference
Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
agriculture could promote the development of a circular
economy by closing ecological loops using wastewater and
organic solid waste as inputs. However, urban agriculture is
not a homogeneous practice, and includes, among the others,
small commercial farms, community-supported agriculture,
community gardens, rooftop gardens or greenhouses,
hydroponic and aquaponics farms and indoor agriculture [17].
Mougeot [18] proposed to categorize UA based on types of
economic activity, products, location, area used, production
system, production scale, and product destination. Given this
variability, a case-by-case evaluation is needed to show if and
in what conditions UA can deliver positive impacts and can
replace conventional agriculture.
Urban agriculture has been studied from a life cycle
perspective, reporting different results that show that UA is
not a less impacting production system per se. For example,
Kulak et al. [14] calculated that up to 34 t CO2eq ha-1 a-1 could
be avoided by substituting conventional agricultural products
with vegetables from community gardens in the UK. On the
other hand, for Goldstein et al. [19] urban agriculture in
northern climates performs worse than its conventional
counterpart, mainly because of its high energy requirement
and/or low yields. Sanyé-Mengual et al. [20] evaluated a
rooftop greenhouse production in Barcelona: their results
show that the UA system had a lower impact on the
environment, but that crop efficiency was determinant for the
performance of the cultivation.
This case study analyses, from an environmental
perspective, a vertical hydroponic urban farm called “La Petite
Ferme du Grand Lyon” and based in Lyon (France), using
Life Cycle Assessment. The pilot farm is run by the private
company ReFarmers and produces leafy greens and herbs that
are sold directly to restaurants and citizens.
2. Methods
Life Cycle Assessment (LCA) is a methodology used for
the evaluation of the environmental impacts of a product or a
service. Its utility in the food sector has been recognized,
thanks also to the opportunity of improving the performance
of a product by acting on the most burdensome processes
2.1. Goal and scope definition
This work’s goal is to evaluate the environmental
performance of a high-yield vertical hydroponic farm, and to
compare it to conventional agriculture. The analysis shows
whether and to what extent this type of hydroponic is able to
produce vegetables with a lower environmental impact than
soil-based conventional agriculture. By showing if urban
agriculture can compete with conventional vegetable
production, this study highlights the strong and weak points of
urban hydroponic production in temperate continental
climates, and therefore supports the improvement and
development of sustainable urban food supply systems.
Urban agriculture is, in this case, a supplementary source
of vegetables; therefore, the capacity of urban hydroponic
agriculture to fulfil the entire food requirement of European
cities is outside of the scope of this study.
The modelling framework applied is attributional LCA.
According to the ILCD Handbook we identified our case
study as a Situation A “micro-level, product or process-related
decision support study”. In fact, by having a small market
share, the farm’s products can impact on the market solely to
a limited extent, generating only small-scale consequences
2.1.1 Functional unit
The selected functional unit is one kg of leafy greens
delivered to the retailer. To be able to perform the comparison
between hydroponic and conventional agriculture, we
assumed that: lettuce and leafy greens can be considered
substitutes, given their almost overlapping function; the
quality of the vegetables is the same for all cultivation types.
The same assumptions were made and described by Goldstein
et al. [19].
2.1.2 System boundaries
We performed a cradle-to-gate analysis considering the
cultivation phase and the transport of the products to the
retailers. Figure 1 shows the boundaries of the system. Capital
goods were included into the analysis as they are considered
fundamental assets in hydroponic cultivation. The end-of-life
of the capital goods was selected depending on the material:
steel, aluminium and iron parts are recycled, as well as PVC
and PE plastic components; the other plastic materials, which
cannot be recycled due to their composition, are sent to
We had to exclude the process of pest control through
insect release; the insects are not bred in the farm, and no
literature data could be found about the breeding process of
parasitoids and the related inputs. The fixation of CO2by the
plants was omitted because the gas is expected to be released
in the near future as a biogenic emission of carbon dioxide.
Moreover, as we compare the same amount of produced
lettuce, the uptake of carbon dioxide is the same for both
types of cultivation. Since the fertilisers are not lost through
the soil, but remain available to the plants thanks to the
recirculation of the water, we assumed the fertilisers
emissions to be zero.
For conventional agriculture, we considered two
scenarios: the production and delivery of lettuce grown in
heated greenhouses (scenario S2) and the production and
delivery of open field cultivated lettuce (scenario S3); both
the scenarios were derived from the Ecoinvent database [23].
In all the three scenarios, the packaging of the vegetables
has not been included. This choice is justified by the fact that
the impact of packaging has been showed to be relatively low
2.1.3 Impact categories
The impact assessment was performed using the software
Simapro 8 and the ReCiPe methodology (version 1.13) at
Midpoint level. We focused on seven impact categories that,
accordingly to Goldstein et al. [19], are considered
representative of the main potential impacts of agriculture:
climate change (CC), freshwater and marine eutrophication
(respectively FE and ME), freshwater ecotoxicity (FT),
agricultural land occupation (ALO), water depletion (WD)
and fossil depletion (FD).
542 Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
2.1.4 Sensitivity analysis
Based on the results of the Life Cycle Impact Assessment
(LCIA), we performed a one-at-a-time (OAT) analysis of
scenario S1; the parameters that contributed most to the
impacts were varied of ±10%, and the change in the results
was calculated and discussed.
A scenario sensitivity analysis was also carried out for
scenarios S1 and S2: the type of one of the most impacting
inputs was changed to see the performance of the scenarios in
these new conditions.
3. Results and discussion
3.1. Life Cycle Inventory
The Life Cycle Inventory (LCI) of scenario S1 (Table 1)
consists of data provided by the farmers, covering four
months of production in 2016. The annual production was
extrapolated considering the seasonal variation of some
inputs, such as the water demand. Moreover, we took into
account that the production stopped for 1.5 months in winter
due to low temperatures. The losses of production in the farm
are indirectly accounted for, since the farmers reported the
yields as production ready to be sold, i.e. the losses has been
already subtracted.
The farm covers an area of around 325 m2, of which (at the
time of the analysis) only 18% were used for the plant
cultivation. The seedlings are not produced in the farm but
bought from a local organic company; since no direct data
were available, we refer to the seedling production process
from Stössel et al. [24]. We assumed no heating is required,
since the plant variety are selected according to the season.
A neighbour farm manages the transport to the retailers of
the vegetables from the hydroponic farm, together with their
production; a mass allocation was performed to distribute the
impacts of this process, and a car trip of 20 km per week was
estimated. No losses of products are assumed in this phase,
due to the length and frequency of the trip.
The Ecoinvent database was the source of the inventories
of scenarios 2 and 3. In particular, we referred to the market
activity dataset “market for lettuce, GLO, Allocation, at the
point of substitution, ecoinvent database version 3.3”, and to
the ordinary datasets “Stössel F., lettuce360 production, GLO
(Global), Allocation, at the point of substitution, ecoinvent
database version 3.3”, and “Stössel F., lettuce361 production,
GLO (Global), Allocation, at the point of substitution,
ecoinvent database version 3.3”.
Table 1. Life Cycle Inventory of scenario S1.
ut U/M Value Lifetime
uts U/M Value Years
reenhouse k
4.34*10-5 15
Iron greenhouse kg 3.01*10-5 50
Aluminium greenhouse kg 3.29*10-4 50
Steel greenhouse kg 2.53*10-3 50
PVC greenhouse kg 1.23*10-4 50
Polyethylene greenhouse kg 6.39*10-4 15
Polycarbonate greenhouse kg 5.71*10-4 15
PVC structure kg 8.87*10-3 20
Recycled PET matrix media kg 7.04*10-3 5
Polyester rope kg 2.83*10-4 6
Steel hanging hook kg 4.96*10-5 50
PVC gutter kg 2.61*10-3 50
PVC pipe kg 1.27*10-4 50
PE tubing kg 2.16*10-4 25
Steel tubing kg 1.02*10-3 50
HDPE tank1 kg 2.31*10-4 25
Steel tank1 kg 2.76*10-4 25
HDPE tank2 kg 1.34*10-4 25
Irrigation pump n 3.73*10-5 10
Sump pump n 3.73*10-5 10
Organic seedlings n 1.96
Peat for seedlings cm339.1
N in fertiliser kg 2.57*10-2
P2O5in fertiliser kg 1.29*10-3
K2O in fertiliser kg 3.60*10-3
Nitric acid L 5*10-3
Potassium hydroxide pest kg 7.97*10-5
Coconut oil pest control kg 7.97*10-5
Water pest control kg 1.85*10-2
Electricity irrigation pump kWh 2.29
Electricity sump pump kWh 0.15
Water irrigation L 5.96
Urban land use m2a 2.24*10-2
Transport t*km 1.00*10-2
Figure 1. System boundaries.
Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
Table 2 reports the yields and the water and fertiliser inputs
required by the three scenarios. In scenario S1, five
cultivation cycles can be achieved per year, while scenarios
S2 and S3 support four cycles per year.
Table 2. Comparison of yield, water and fertiliser consumption of the three
types of cultivation.
3.2. Life Cycle Impact Assessment
As an overview, the urban vertical hydroponic production
(S1) shows the best performance in the categories of marine
eutrophication and agricultural land occupation. For climate
change, freshwater eutrophication, freshwater ecotoxicity and
fossil depletion, the impact is higher than on-field
conventional agriculture (S3). Anyway, in all cases except for
water depletion the performance of S1 is visibly better than
the production of lettuce in heated greenhouses (S2).
These results are explained by taking into consideration the
characteristics of the different systems. The vertical
hydroponic farm requires more capital goods than the other
types of cultivations, since it does not rely on soil substrate,
but needs vertical plastic structures and a recirculating
irrigation system, which requires electricity (see Figure 2).
For climate change, the consumption of electricity
contributes for two thirds to the impact in scenario S1, while
in scenario S3 the production and use of fertilisers are the
main responsible of greenhouse gas (GHG) emissions.
Whereas these two scenarios differ for only 0.10 kg CO2eq,
when lettuce is grown in heated greenhouses (scenario S2), it
is responsible of the emission of 7.08 kg CO2eq per every kg
of lettuce that reaches the supermarket.
By recirculating water and avoiding losses for infiltration,
scenario S1 has a water consumption seven times lower than
greenhouse conventional production, and around four times
lower than on-field cultivation, that benefits from rain events
(see Table 2). In Mediterranean climates, such as Greece, the
water demand per kg of lettuce production reaches 83 litres,
fourteen times higher than in vertical hydroponics [25].
However, the irrigation system requires a constant water flow
guaranteed by a pumping system, which consumes electricity.
The impact of electricity depends on how this electricity is
produced; given the location of the farm, we considered the
French energy mix, of which more than 70% is nuclear energy
[26]. The production of nuclear energy has a high requirement
of cooling-water, which explains why scenario S1 has a worse
impact on water depletion, even if it has a smaller direct water
Table 3. Results of the Life Cycle Impact Assessment of 1 kg of lettuce
grown in the three scenarios: vertical hydroponic production (S1), heated
greenhouse production (S2) and on-field cultivation (S3). The results are
normalised with respect to the yields in Table 2.
The consumption of electricity for irrigation is among the
main contributing processes for all the impact categories, but
is less impacting than the consumption of heat of the
conventional greenhouse scenario. In facts, scenario S2 has
the worst performance (except for water depletion) in every
The controlled temperature in S2 results in a doubled yield
with respect to on-field cultivation, but still half of the one of
vertical hydroponic (see Table 2). Having a high production
in a limited space is one of the main qualities of vertical
hydroponic systems. Moreover, since no soil is needed, the
cultivation can take place in many different spaces: on
rooftops, indoor, on abandoned industrial sites, on walls. An
additional positive characteristic of hydroponics is that the
quality and eventual contamination of the soil does not
represent a risk for the products – simply because the two
compartments are not in direct contact. This advantage is
shown in the agricultural land occupation of scenario S1: by
being soil independent and vertical, this type of hydroponics
requires from four to 20 times less agricultural land than
conventional agriculture.
However, this means that hydroponic production needs to
be supported by an external input of fertilisers to satisfy the
nutrient requirement of the plants. The use of NPK fertiliser in
the three scenarios is reported in Table 2. Scenario S1 needs
more nutrient input than greenhouse cultivation, but less than
on-field production, where part of the applied fertilisers is lost
due to leaching processes. The different NPK proportion
indicates that hydroponics allows an optimization of nutrient
supply to support the growth phases of the plants.
S1 S2 S3
Yield [kg/m2year] 44.7 20.0 10.4
Water consumption [L/kg] 5.96 42.3 23.2
Fertiliser use per kg of
product [kg/kg]:
N 0.0026 0.0016 0.0037
P as P2O50.0013 0.0005 0.0007
K as K2O 0.0036 0.0024 0.0052
Table 3 reports the results of the Life Cycle Impact
Assessment for the four scenarios.
Impact category S1 S2 S3
CC [kg CO2eq] 0.39 7.1 0.29
FE [kg Peq] 5.88*10-5 3.10*10-4 1.27*10-5
ME [kg Neq] 1.14*10-4 8.91*10-4 1.37*10-3
FT [kg 1,4-DBeq] 2.55*10-4 9.98*10-4 1.69*10-4
ALO [m2a] 0.024 0.522 0.095
WD [m3] 0.033 0.019 0.017
FD [kg oileq] 0.10 1.43 0.07
Figure 2. Process contribution of scenario S1 in the seven impact categories
544 Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
These results do not completely explain the impacts on
freshwater eutrophication: in scenarios S1 the production of
electricity and fertilisers are the main contributing processes,
and in scenario S2 the production of heat is the dominant
process. Scenario S3 has a negligible use of these inputs, but
needs more fertilisers, which determines the emission of
nutrients into the water streams. It is important to distinguish
where the emissions of nutrients take place, since
eutrophication is a local phenomenon. In this sense, in
scenario S1 and S2 the major risk of eutrophication is in the
areas where fuels, metals and fertilisers are extracted, i.e.
mining sites distant from the place of final use. On the
contrary, in scenario S3 the release of nutrients following the
application of fertilisers represents a noteworthy impact on
local water quality.
About marine eutrophication, the actors in play are the
same of freshwater eutrophication (electricity, fertiliser
production and use), but since scenario S3 has a high release
of nitrogen (which is the limiting factor of ME), its impact is
higher than scenario S1.
Regarding eutrophication, a merit of hydroponics is the
efficient use of nutrients, that, by being recycled with the
water, are not released through the soil but remain available
for the plants. The impact on freshwater ecotoxicity is due to
the heat consumption in scenario S2, whereas for the other
two scenarios several processes impact with the same order of
magnitude: electricity production, fertiliser production,
equipment production, pesticide production and transport.
The combination of equipment and energy requirements is
responsible of the impact of scenario S1 on fossil depletion.
Scenario S2, due to the necessity to heat the greenhouse, has a
performance more than ten times worse, while on-field
cultivation (S3), that is relatively low-input, has half the
impact of S1.
A benefit of urban agriculture is the shortening of the
supply chain and the reduction of losses during the transport
of the products. Thanks to the proximity of the farm to the
consumers, the vegetables are fresher and do not need to be
cooled during the delivery. For these reasons, we assumed
zero losses in the transport phase. For conventional
agriculture, on the other hand, the reported distribution losses
are approximately 12%.
3.2.1 Sensitivity analysis
To determine the influence of the main inputs identified in
the LCIA, we performed a one-at-a-time (OAT) analysis of
scenario S1 by varying the yield, the electricity consumption
and the water consumption by ±10%. The results in Table 4
show that the yield is the parameter that most affects the
results, especially when it changes negatively. Variations in
electricity consumption have different effects on the different
categories, but notably this parameter is more important than
water for the water depletion impact category.
We performed also a scenario sensitivity analysis where we
considered the case in which the hydroponic farm (S1) and
the heated-greenhouse farm (S2) use only wind energy to
satisfy their energy requirements. We chose this type of
energy because wind is the second renewable energy source in
France, after hydropower, and is easier to implement than the
latter [26].
Table 4. OAT sensitivity analysis.
As visualized in Table 5, the use of wind energy makes the
hydroponic production the least impacting method of
cultivation, except for the impacts on freshwater where it is
comparable to on-field agriculture. The use of wind energy in
the heated greenhouse improves the overall performance of
this scenario, however, this cultivation remains the one with
the highest impacts on the considered categories.
Table 5. Scenario sensitivity analysis: LCIA of scenario S1 using wind
energy as electricity input.
3.2.2 Data quality and limitations of the study
The quality of the data influences the results. The primary
data collected for scenario S1 refer to four months of
production. Even if the farmers considered the seasonal
variability for a better estimation of the annual consumptions,
e.g. the water consumption, we recognise that the annual
estimations could eventually not correspond to the actual
Moreover, scenarios S2 and S3 are based on LCI datasets
representative of the Integrated Production in Switzerland.
Even though the authors of the datasets affirm that, most
probably, their data are representative for similar cultivations
in industrialised countries, these values cannot capture the
peculiarities of country-specific cultivation practices. In
conclusion, we acknowledge that the data do not have the
same level of precision, and this affects the quality of the
To compare the performance of the systems, we chose the
environmental indicators considered the most representative
for LCA analyses of agricultural systems. We recognise that
the agricultural sector can deliver other positive and negative
effects, such as potential contribution to biodiversity, social
issues and economic development. Consequently, integrating
the analysis with other methodologies could give a broader
perspective on the impacts of agriculture on an environmental,
economic and social level.
Impact category Yield
CC [kg CO2eq] -9.1% +11.1% ±6.7% ±0.1%
FE [kg Peq] -9.1% +11.1% ±7.9% ±0.0%
ME [kg Neq] -9.1% +11.1% ±3.9% ±0.0%
FT [kg 1,4-DBeq] -9.1% +11.1% ±3.7% ±0.0%
ALO [m2a] -9.1% +11.1% ±3.1% ±0.1%
WD [m3] -9.1% +11.1% ±7.0% ±1.8%
FD [kg oileq] -9.1% +11.1% ±6.5% ±0.1%
Impact category S1 wind energy S2 wind energy
CC [kg CO2eq] 0.156 1.139
FE [kg Peq]1.61*10-5 6.60*10-5
ME [kg Neq]7.86*10-5 6.72*10-4
FT [kg 1,4-DBeq] 1.74*10-4 2.98*10-4
ALO [m2a] 0.0017 0.071
WD [m3]0.011 0.018
FD [kg oileq] 0.044 0.252
Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
4. Conclusions
The results of the comparative analysis of lettuce
production in vertical hydroponic, heated greenhouse and on-
field cultivation show that the former is able to deliver higher
yields and have an environmental impact comparable to on-
field cultivation, and 2 to 12 times lower than heated
greenhouse production. A special case is represented by the
impact on water depletion, where the type of energy used
affects the results more than the direct water consumption. In
conclusion, the need of energy inputs is determinant for the
efficiency of plant production systems, as highlighted by the
bad performance of scenario S2, due to the need for heating.
When the needs of external inputs are satisfied using fossil-
based resources, the environmental performance decreases,
but if renewable sources are used, the high yields and
efficiency make vertical hydroponic the best production
system in the considered climatic area. Moreover, the ability
to grow local food without agricultural land occupation is for
sure an added value of vertical hydroponics, representing a
less environmentally harmful way to supplement the
vegetable demand of urban populations.
The research was performed as part of the DECISIVE
(Decentralised valorisation of biowaste) project
(, funded by the European Union’s
Horizon 2020 research and innovation program under the
grant agreement N° 689229 and the Graduate School of
Science and Technology at Aarhus University. We thank our
project partner ReFarmers for sharing their data.
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... Considered at all relevant life cycle stages of the functional unit, results are used in this study to compare impacts of IVF and of UA supply chains [53]. Generating results for indicators such as GWP in CO 2 e per kg supports comparison with other LCA research into IVF technology [12,[58][59][60]. Ecotoxicity impact categories were applied as representative of toxicity impacts on urban environments [33], and serve to assess the technologies' impact on freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity and human toxicity [57] (Table S2 and Figure S1). ...
... In CS, it is responsible for 10.01 kg (54%) and LS for 10.03 kg CO2e/kg (45%). This result was expected in an IVF system, as high energy demand in urban farm operations is a known challenge [46,[58][59][60]. In this study the primary consumption of electricity was from four inputs (climate system and equipment, LEDs and cleaning). ...
... In CS, it is responsible for 10.01 kg (54%) and LS for 10.03 kg CO 2 e/kg (45%). This result was expected in an IVF system, as high energy demand in urban farm operations is a known challenge [46,[58][59][60]. In this study the primary consumption of electricity was from four inputs (climate system and equipment, LEDs and cleaning). ...
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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.
... A large share of the scientific and grey literature promotes vertical farming as a sustainable solution for food provisioning (Al-Chalabi, 2015;Benke and Tomkins, 2017;Despommier, 2011). However, assessments of the environmental implications of IVFs remain limited in scientific literature, with few cases applying systematic environmental assessments (Dorr et al., 2021;Martin et al., 2022;Romeo et al., 2018). A number of theoretical studies have assessed IVFs to compare their performance against competing systems such as open-field production and greenhouses, see e.g. ...
... In previous studies, packaging has been found to contribute only to a small share of the environmental impacts of IVFs. However, a large number of studies have also excluded packaging from their assessment (Graamans et al., 2018;Romeo et al., 2018;Weidner et al., 2022) motivating its minor share of the overall impacts. However, despite its relatively small share to the overall impacts, annually the total consumption of certain materials may contribute to a large environmental footprint (e.g. ...
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Indoor vertical farms (IVF) have expanded rapidly in recent years as an approach to secure resilient food provisioning in urban areas. Sustainability is often promoted by IVFs, focusing primarily on farm-level metrics and information about work with packaging. However, there are few assessments of the implications IVFs have throughout their life cycle due in part to the novelty of the industry. This chapter aims to provide information and guidance on conducting an environmental sustainability assessment of an IVF employing life cycle assessment (LCA) methodology. Throughout the chapter, the different phases of an LCA are outlined, and guidance is provided for practitioners in order to aid their work, assumptions, and methodological choices. Furthermore, important processes and insights from previous research are provided to promote a more sustainable IVF industry.
... Many authors promote these systems as a sustainable solution for urban areas (Despommier, 2009;Benke and Tomkins, 2017;Van Delden et al., 2021). However, evaluations of their benefits remain limited in the literature, with few studies assessing the sustainability of the systems (Romeo et al., 2018;Sanjuan-Delmás et al., 2018;Gentry, 2019;. Furthermore, despite some studies addressing the potential benefits of including these systems in urban environments (Eigenbrod and Gruda, 2015;Kozai and Niu, 2016;Eaves and Eaves, 2018), the literature remains limited. ...
... This stems largely from electricity demand from LED lighting and the HVAC system. These results concur with a number of previous studies, suggesting that energy consumption for artificially maintained climatic and light regimes contribute significantly to the environmental impacts of such systems; see, e.g., Chance et al. (2018), Romeo et al. (2018), and . This was also apparent in the sensitivity analysis, where the choice of electricity heavily influenced the results. ...
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Vertical farms have expanded rapidly in urban areas to support food system resilience. However, many of these systems source a substantial share of their material and energy requirements outside their urban environments. As urban areas produce significant shares of residual material and energy streams, there is considerable potential to explore the utilization of these streams for urban agriculture in addition to the possibility of employing underutilized urban spaces in residential and commercial buildings. This study aims to explore and assess the potential for developing more circular vertical farming systems which integrate with buildings and utilize residual material and energy streams. We focus on the symbiotic development of a hypothetical urban farm located in the basement of a residential building in Stockholm. Life cycle assessment is used to quantify the environmental performance of synergies related to energy integration and circular material use. Energy-related scenarios include the integration of the farm's waste heat with the host building's heating system and the utilization of solar PV. Circular material synergies include growing media and fertilizers based on residual materials from a local brewery and biogas plant. Finally, a local pickup system is studied to reduce transportation. The results point to large benefits from integrating the urban farm with the building energy system, reducing the vertical farm's GHG emissions up to 40%. Synergies with the brewery also result in GHG emissions reductions of roughly 20%. No significant change in the environmental impacts was found from the use of solar energy, while the local pickup system reduces environmental impacts from logistics, although this does not substantially lower the overall environmental impacts. However, there are some trade-offs where scenarios with added infrastructure can also increase material and water resource depletion. The results from the synergies reviewed suggest Martin et al. Urban Symbiotic Vertical Farming that proximity and host-building synergies can improve the material and energy efficiency of urban vertical farms. The results provide insights to residential building owners on the benefits of employing residual space for urban food provisioning and knowledge to expand the use of vertical farming and circular economy principles in an urban context.
... Sustainability of food production systems has been investigated using scientifically reliable methods. Some studies have been conducted to measure the sustainability of biofloc de Lima Vieira et al., 2021) and hydroponic systems (Martin and Molin, 2019;Romeo et al., 2018), but none were found for FLOCponics. ...
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FLOCponics is an intensive integrated agri-aquaculture system that combines biofloc-based aquaculture with hydroponics. Since research on FLOCponics is in its early stage of development, and many aspects of this system still need to be explored, the objective of this study was to assess and discuss the sustainability of a FLOCponics system and compare it to stand-alone biofloc and hydroponic cultures. This investigation will lead to a novel perspective of what troubling points need to be covered in the FLOCponics research field before they turn into a commercial scale problem. To do this, we conducted an experiment-based study by applying emergy synthesis to assess the sustainability of tilapia juveniles and lettuce production in FLOCponics, biofloc and/or hydroponic systems. The results indicate that the resources from the larger economy were the inputs that made the greatest contribution in all systems. Overall, most of the emergy indicators are similar for all systems, suggesting that FLOCponics, biofloc and hydroponic systems use low amounts of natural renewable resources, cause a moderate environmental load (EIR and ELR of 3.1 to 3.6), and lead to environmental stress seven times higher than the contribution to the economy (ESI of 0.3). Unit emergy values (UEVs) are different for each system, indicating that, under the evaluated conditions, FLOCponics (UEV: 2.54E + 06 sej/J) is more efficient than hydroponics (UEV: 5.55E + 10 sej/J) and less efficient than a biofloc system (UEV: 1.42E + 06 sej/J). Our findings provide valuable insights regarding the (un)sustainable aspects of FLOCponics and direct further research to improve the system's emergy performance. Based on the emergy performance, FLOCponics can be considered a promising sustainable food production approach, mainly considering that it is a system under development and there are still many opportunities for improvement.
... To systematically assess the environmental advantages and disadvantages of vertical approaches compared to traditional methods of food production, it would be useful to look at an LCA, although only a very limited number of such analyses of vertical or similar systems have been published at present [163]. ...
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Resources such as fertile soil and clean water are already limited in many parts of the world. Additionally, the conventional use of arable land is becoming increasingly difficult, which is further exacerbated by climate change. Soilless cultivation systems do not only offer the opportunity to save water and cultivate without soil but also the chance to open up urban areas such as residential rooftops for food production in close proximity to consumers. In this review, applications of soilless farming systems are identified and compared to conventional agriculture. Furthermore, aspects of economic viability, sustainability and current developments are investigated. An insight into the most important soilless farming systems—hydroponics, aquaponics and vertical farming—is provided. The systems are then differentiated from each other and, as far as possible, evaluated in terms of their environmental impact and compared with conventional cultivation methods. Comparing published data analyzing the yield of hydroponic cultivation systems in comparison to soil-based cultivation methods enables a basic overview of the profitability of both methods and, thus, lays the foundation for future research and practical applications. The most important inert substrates for hydroponic applications are presented, and their degree of sustainability is compared in order to emphasize environmental impacts and affect substrate selections of future projects. Based on an assessment of the most important soilless cultivation systems, the challenges and developments of current techniques are highlighted and discussed.
Attributional life cycle assessment was applied to determine environmental footprints of lettuce produced across ten supply chain configurations, based on either hydroponic closed-environment agriculture (CEA) with six different electricity sources, or field supply chains involving regional, continental or inter-continental transport. Hydroponic CEA systems use circa 15 kWh of electricity for lighting, cooling, ventilation and pumping per kg of lettuce supplied. Based on typical current national grid electricity generation mixes with significant fossil fuel dependence, this results in large environmental footprints, e.g. up to 17.8 kg CO2 eq. and 33 g N eq. per kg lettuce – compared with 10 kg CO2 eq. and 16 g N eq. per kg lettuce air-freighted across continents. However, hydroponic CEA can produce orders of magnitude more produce per m².yr and can be integrated into existing buildings (e.g. on roof tops, in basements and disused warehouses, etc). Factoring in the carbon opportunity costs of land use, and meeting electricity requirements exclusively through renewable generation, could result in closed hydroponic CEA delivering produce with a smaller carbon footprint than most field-based supply chains, at 0.48 kg CO2 eq. per kg lettuce. However, this would only be the case where renewable electricity originates from genuinely additional capacity, and where a land use policy or other mechanisms ensure that modest areas of land spared from horticultural production are used for “nature based solutions” such as afforestation. Hydroponic CEA uses orders of magnitude less direct water than field-based systems, and could help to mitigate water stress and associated soil degradation in arid and semi-arid regions used for horticulture – so long as upstream water stress associated with electricity generation is mitigated. CEA could be one of the least sustainable forms of food production if poorly implemented, and has numerous environmental hotspots. But with careful design and scaling, in appropriate contexts of high demand and low agro-climatic potential for production of horticultural produce, CEA deployment could play a role in sustainable food system transformation, potentially helping to reconnect consumers with (urban) producers. There may be opportunities to link building air handling systems with rooftop or basement CEA requiring inputs of cooling, CO2 and water.
This chapter starts with a classification of controlled environment agriculture types: rooftop greenhouses, façade farms and plant factories that utilise sunlight or rely solely on artificial lighting sources. When designing a viable scenario for the adaptive reuse of buildings for food production, an architect must make strategic decisions in the planning, architectural and environmental dimensions. The literature review on opportunities and limitations for repurposing urban structures for food production within these thematic categories is presented and summarised. Then these findings are applied to the three building-based farming operations. The case study reveals that the opportunities and limitations in the planning domain are similar for all types of controlled environment agriculture. However, the architectural and environmental analysis indicated a different potential to place food growing installations arising from specific attributes of the building.
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The past decade has seen a renaissance of urban agriculture in the world's wealthy, northern cities. The practice of producing food in and around cities is championed as a method to reduce environmental impacts of urban food demands (reducing distance from farm to fork - ‘food miles’) whilst conferring a number of ancillary benefits to host cities (runoff attenuation, urban heat island mitigation) and ex-urban environments (carbon sequestration). Previous environmental assessments have found urban agriculture to be more sustainable than conventional agriculture when performed in mild climates, though opposite findings emerge when external energy inputs are significant. In this study we perform an environmental life cycle assessment of six urban farms in Boston, US producing lettuce and tomatoes, with conventional counterparts across six impact categories. Performance of urban agriculture was system dependent and no farm provided superior performance to conventional for all indicators. High-yield, heated, greenhouse production of tomatoes has potentially higher environmental burdens than conventional methods in terms of climate change (267–369%) and non-renewable resource depletion (108–239%), driven primarily by external energy inputs. Heated lettuce production systems showed similar trends. Low-tech, empty-lot farming appears to hold some advantages in terms of climate change burdens and resource use, though water and land usage was found to be elevated relative to conventional lettuce and tomatoes. Open rooftop farming apparently provides benefits if high yield crops (e.g. tomatoes) are cultivated, otherwise significant capital inputs detrimentally affect environmental performance. In general, the benefits of reduced food miles may be overwhelmed by energy inputs and inefficient use of production inputs. A comparison of urban agriculture and solar panels showed that the latter would confer greater benefits to mitigate climate change per unit area. Thus, urban agriculture may not be the optimal application of space in northern cities to improve urban environmental performance.
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Purpose Good background data are an important requirement in LCA. Practitioners generally make use of LCI databases for such data, and the ecoinvent database is the largest transparent unit-process LCI database worldwide. Since its first release in 2003, it has been continuously updated, and version 3 was published in 2013. The release of version 3 introduced several significant methodological and technological improvements, besides a large number of new and updated datasets. The aim was to expand the content of the database, set the foundation for a truly global database, support regionalized LCIA, offer multiple system models, allow for easier integration of data from different regions, and reduce maintenance efforts. This article describes the methodological developments. Methods Modeling choices and raw data were separated in version 3, which enables the application of different sets of modeling choices, or system models, to the same raw data with little effort. This includes one system model for Consequential LCA. Flow properties were added to all exchanges in the database, giving more information on the inventory and allowing a fast calculation of mass and other balances. With version 3.1, the database is generally water-balanced, and water use and consumption can be determined. Consumption mixes called market datasets were consistently added to the database, and global background data was added, often as an extrapolation from regional data. Results and discussion In combination with hundreds of new unit processes from regions outside Europe, these changes lead to an improved modeling of global supply chains, and a more realistic distribution of impacts in regionalized LCIA. The new mixes also facilitate further regionalization due to the availability of background data for all regions. Conclusions With version 3, the ecoinvent database substantially expands the goals and scopes of LCA studies it can support. The new system models allow new, different studies to be performed. Global supply chains and market datasets significantly increase the relevance of the database outside of Europe, and regionalized LCA is supported by the data. Datasets are more transparent, include more information, and support, e.g., water balances. The developments also support easier collaboration with other database initiatives, as demonstrated by a first successful collaboration with a data project in Québec. Version 3 has set the foundation for expanding ecoinvent from a mostly regional into a truly global database and offers many new insights beyond the thousands of new and updated datasets it also introduced.
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Global food production faces great challenges in the future. With a future world population of 9.6 billion by 2050, rising urbanization, decreasing arable land, and weather extremes due to climate change, global agriculture is under pressure. While today over 50 % of the world population live in cities, by 2030, the number will rise to 70 %. In addition, global emissions have to be kept in mind. Currently, agriculture accounts for around 20–30 % of global greenhouse gas emissions. Shifting food production to locations with high demands reduces emissions and mitigates climate change. Urban horticulture increases global food production by exploiting new locations for cultivation. However, higher land prices and urban pollution constrain urban horticulture. In this paper, we review different urban cultivation systems throughout the world. Our main findings from ecological, economical, and social aspects are: (1) Urban horticulture activities are increasing globally with at least 100 million people involved worldwide. With potential yields of up to 50 kg per m2 per year and more, vegetable production is the most significant component of urban food production which contributes to global food security. (2) Organoponic and other low-input systems will continue to play an important role for a sustainable and secure food production in the future. (3) Despite the resource efficiency of indoor farming systems, they are still very expensive. (4) Integrating urban horticulture into educational and social programs improves nutrition and food security. Overlaying these, new technologies in horticultural research need to be adopted for urban horticulture to increase future efficiency and productivity. To enhance sustainability, urban horticulture has to be integrated into the urban planning process and supported through policies. However, future food production should not be “local at any price,” but rather committed to increase sustainability.
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Purpose Rooftop greenhouses (RTGs) are increasing as a new form of urban agriculture. Several environmental, economic, and social benefits have been attributed to the implementation of RTGs. However, the environmental burdens and economic costs of adapting greenhouse structures to the current building legislation were pointed out as a limitation of these systems in the literature. In this sense, this paper aims to analyse the environmental and economic performance of RTGs in Barcelona. Methods A real RTG project is here analysed and compared to an industrial greenhouse system (i.e. multi-tunnel), from a life cycle perspective. Life cycle assessment (LCA) and life cycle costing (LCC) methods are followed in the assessment. The analysis is divided into three parts that progressively expand the system boundaries: greenhouse structure (cradle-to-grave), at the production point (cradle-to-farm gate), and at the consumption point (cradle-to-consumer). The applied LCIA methods are the ReCiPe (hierarchical, midpoint) and the cumulative energy demand. A cost-benefit analysis (CBA) approach is considered in the LCC. For the horticultural activity, a crop yield of 25 kg · m−2 is assumed for the RTG reference scenario. However, sensitivity analyses regarding the crop yield are performed during the whole assessment. Results and discussion The greenhouse structure of an RTG has an environmental impact between 17 and 75 % higher and an economic cost 2.8 times higher than a multi-tunnel greenhouse. For the reference scenario (yield 25 kg · m−2), 1 kg of tomato produced in an RTG at the production point has a lower environmental impact (10–19 %) but a higher economic cost (24 %) than in a multi-tunnel system. At the consumption point, environmental savings are up to 42 % for local RTGs tomatoes, which are also 21 % cheaper than conventional tomatoes from multi-tunnel greenhouses in Almeria. However, the sensitivity assessment shows that the crop efficiency is determinant. Low yields can produce impacting and expensive vegetables, although integrated RTGs, which can take advantage from the residual energy from the building, can lead to low impacting and cheap local food products. Conclusions RTGs face law limitations that make the greenhouse structure less environmentally friendly and less economically competitive than current industrial greenhouses. However, as horticultural systems and local production systems, RTGs can become an environmentally friendly option to further develop urban agriculture. Besides, attention is paid to the crop yield and, thus, further developments on integrated RTGs and their potential increase in crop yields (i.e. exchange of heat and CO2 with the building) are of great interest.
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This article examines the role played by urban gardens during historical collapses in urban food supply lines and identifies the social processes required to protect two critical elements of urban food production during times of crisis—open green spaces and the collective memory of how to grow food. Advanced communication and transport technologies allow food sequestration from the farthest reaches of the planet, but have markedly increasing urban dependence on global food systems over the past 50 years. Simultaneously, such advances have eroded collective memory of food production, while suitable spaces for urban gardening have been lost. These factors combine to heighten the potential for food shortages when—as occurred in the 20th century—major economic, political or environmental crises sever supply lines to urban areas. This paper considers how to govern urban areas sustainably in order to ensure food security in times of crisis by: evincing the effectiveness of urban gardening during crises; showing how allotment gardens serve as conduits for transmitting collective social-ecological memories of food production; and, discussing roles and strategies of urban environmental movements for protecting urban green space. Urban gardening and urban social movements can build local ecological and social response capacity against major collapses in urban food supplies. Hence, they should be incorporated as central elements of sustainable urban development. Urban governance for resilience should be historically informed about major food crises and allow for redundant food production solutions as a response to uncertain futures.
Urban agriculture appears to be a means to combat the environmental pressure of increasing urbanization and food demand. However, there is hitherto limited knowledge of the efficiency and scaling up of practices of urban farming. Here, we review the claims on urban agriculture’s comparative performance relative to conventional food production. Our main findings are as follows: (1) benefits, such as reduced embodied greenhouse gases, urban heat island reduction, and storm water mitigation, have strong support in current literature. (2) Other benefits such as food waste minimization and ecological footprint reduction require further exploration. (3) Urban agriculture benefits to both food supply chains and urban ecosystems vary considerably with system type. To facilitate the comparison of urban agriculture systems we propose a classification based on (1) conditioning of the growing space and (2) the level of integration with buildings. Lastly, we compare the predicted environmental performance of the four main types of urban agriculture that arise through the application of the taxonomy. The findings show how taxonomy can aid future research on the intersection of urban food production and the larger material and energy regimes of cities (the “urban metabolism”).
The environmental sustainability of an organic and a conventional lettuce cultivation system, situated at Northern Greece, was investigated. Data from all stages (i.e. irrigation, machinery used, and fertilizing) of lettuce cultivation were collected and their sustainability was assessed by means of the life cycle assessment (LCA) methodology. Two different functional units, namely per hectare of cultivation and per ton of lettuce produced, were used and the environmental impacts, on mid and endpoint level, and CO2 emissions were estimated by means of the SimaPro 8 LCA software. It was found that the environmental footprint and the CO2 emissions were lower by 11% and 15%, respectively, for organic than for the conventional lettuce cultivation, when sustainability was assessed per area (ha) of cultivation. On the contrary, conventional lettuce cultivation showed a better environmental performance than organic by 51% and 53% in terms of CO2 emissions and total environmental impacts, respectively, when the amount of lettuce produced is used as the functional unit of calculations. This is attributed to the fact that the organic system, due to its lower crop yields, requires significantly larger cultivation area to achieve the same crop production with conventional. Moreover, it was found that in all cases the irrigation stage primarily contributed to most impact categories, due to its high energy demands for ground water pumping and the fossil-dependent Greek electricity grid. In addition, in all cases the conventional lettuce cultivation system yielded a significantly high impact onto freshwater eutrophication, due to the use of chemical fertilizers, thus posing serious stresses on local freshwater ecosystems. A sensitivity analysis was carried out and alternative, more sustainable, scenarios were proposed.
The production and supply of food currently accounts for 20–30% of greenhouse gas (GHG) emissions in the UK and the government and nongovernmental organisations are seeking to reduce these environmental burdens. Local authorities all over UK establish community farms with the aim to produce more sustainable food for citizens. This study used environmental Life Cycle Assessment (LCA) to quantify the potential savings of food-related GHG emissions that may be achieved with the establishment of an urban community farm, based on a case study recently found in the London Borough of Sutton. The work identified elements of the farm design that require the greatest attention to maximise these savings. The greatest reductions can be achieved by selecting the right crops: (i) providing the highest yields in local conditions and (ii) usually produced in energy-intensive greenhouses or air-freighted to UK from outside Europe. Implications from further development of the farm on the local, unused land were examined, taking into account market requirements. This showed that land used on an urban fringe for food production could potentially reduce greenhouse gas emissions in Sutton by up to 34 t CO2e ha−1 a−1. Although the percentage of this reduction in total diet emissions is relatively low, the result exceeds carbon sequestration rates for the conventional urban green space projects, such as parks and forests.
This paper describes how cities can be transformed from being only consumers of food and other agricultural products into important resource-conserving, health-improving, sustainable generators of these products. In particular, agriculture in towns, cities and metropolitan areas can convert urban wastes into resources, put vacant and under-utilized areas into productive use, and conserve natural resources outside cities while improving the environment for urban living. Agriculture within urban and peri-urban areas is defined as a common and beneficial land use. This paper also gives examples of urban agriculture programmes which help alleviate poverty while creating these benefits. -Authors