Life cycle assessment of indoor vertical farms

Abstract

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.

Full text

Life cycle assessment of
indoor vertical farms
Michael Martin
1,2
, Francesco Orsini
3
1. IVL Swedish Environment al Researc h Institute, Life Cycle Manageme nt, Sustainable Society, Vallhallavä gen
81, 114 28 Stockholm, Sw eden
2. KTH Roya l Instit ute of Technology, Dep artment of Sustainable Develop ment, Environme ntal Science and
Engineering, Teknikringen 10 B, 114 28 Stockholm, Sweden
3. University of Bol ogna, Department of Agricultural and Foo d Science s, Alma Mater Studi orum, viale Fanin
44, 40127 Bologna , Italy
Abstract
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.
1. Introduction
It is becoming increasingly important to find solutions for more resilient food production
methods closer to urban environments with less vulnerability to supply-chain shocks (Benke
and Tomkins, 2017; O’Sullivan et al., 2020; Pulighe and Lupia, 2020). Indoor vertical l farming
This is the accepted version of the chapter. The final version will be available
in Advances in plant factories: New technologies in indoor vertical farming
(ed. Emeritus Prof. Toyoki Kozai and Dr. Eri Hayashi), Burleigh and Dodds,
forthcoming 2022. The material cannot be used for any other purpose without
further permission of the publisher, and is for private use only.

(IVF
1
) systems have emerged worldwide as a result of the need for more resilient food
provisioning. IVF has been promoted for its potential to extend the seasonal availability,
produce more sustainable food, secure food supplies, and reduce pressure on agricultural
land (Graamans et al., 2018; Martin and Molin, 2019; Thomaier et al., 2014; van Delden et al.,
2021). Furthermore, IVF has seen a dramatic increase in recent years, attracting considerable
interest and funding (Agritecture, 2022; Orsini et al., 2020; Weidner et al., 2019)
IVFs are relatively new in the context of food supply chains, and thus it is an expanding
subject of inquiry. 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 and Molin, 2019; 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. (Graamans et al., 2018;
Weidner et al., 2021; Weidner et al., 2022). Nonetheless, empirical evidence from real case
studies is lacking in the literature, which may be due in part to their novelty and evolving
nature. As such, there are few studies that validate claims made by vertical farming of their
resource efficiency and reduced environmental impacts, which are often focused primarily
on the farm-level metrics.
Consumers, businesses, and decision-makers are becoming increasingly attentive to the use
of feedback and information through credible systems to communicate and evaluate the
environmental impacts of goods and services. In particular, the food sector has been
increasingly employing life cycle assessment for highlighting the ‘footprint’ of their products
(Freidberg, 2014). Employing life cycle assessments (LCA) may be an important methodology
for IVFs to meet the criticism of many of the claims in the industry and provide knowledge
for working with sustainability more strategically, providing transparent and scientifically
based metrics.
This chapter aims to provide insights on conducting an environmental sustainability
assessment of an IVF employing life cycle assessment methodology and outline important
considerations during the process. The chapter is designed to provide an overview of the
method, and thereafter describe the different phases of conducting a life cycle assessment,
providing guidance specifically for IVFs. It also outlined the limitations of employing LCA
and provides knowledge on challenges, important aspects, and possibilities to improve the
environmental performance of IVFs based on previous research. The methodology and
insights are applicable to different forms of IVF. This includes assessments of, for example,
the production of edible crops, mushrooms, and production of crops for other purposes
(e.g. pharmaceutical applications).
2. LCA and its application in IVF
Life Cycle Assessment (LCA) is a broadly employed and accepted method in which the
environmental impacts related to a product system or service are quantified and illustrated
1
The acronym IVF henceforth refers to the verb ‘indoor vertical farming’ to denote the practice and
the noun ‘indoor vertical farm’ to denote the sites.

during its life cycle, i.e., from raw material extraction via production and use phases to
waste management and transportation (Finnveden et al., 2013). The method has been used
for several decades and has even been standardized by the International Standards
Organization (ISO, 2006). It is used by organizations to identify so-called ‘hot-spots’ in their
life cycle which can be used to improve processes and make strategic decisions on the best
course of action to improve. LCA also provides information that can be used for labeling
and decision-making.
According to ISO 14044 (2006), the process of conducting an LCA is based on four required
steps (also referred to as phases), including 1) goal and scope definition, 2) inventory
analysis, 3) environmental impact assessment, and 4) interpretation, see Figure 1 below.
These steps are specifically reviewed in subsequent sections with application to applying
LCA of IVFs.
Figure 1: Elements of the Life Cycle Assessment Method (based on ISO, 2006)
Goal and Scope of the Study
In the first step, the goal and scope of the LCA are defined to ensure that the outcome is
consistent with the objectives, setting the context for the study. For this step, it is important
that the purpose of the study is clearly defined in the documentation but also agreed upon
between those conducting the LCA and the receiver (typically the client). For example, this
can include the intended application of the study, such as communication, comparative
assertions, product improvement, planning processes, strategic decisions, or policy-making.
It is also important to highlight the conditions and assumptions for which the results of the
assessment are valid, which are of utmost importance to the study.
In the scope description, the definition of the functional unit, i.e. the service delivered by the
product system, is critical to agree upon. Specifically for IVFs this is typically associated
with the production output, e.g. one kilogram of the edible portion (fresh weight) of a
particular food available to consumers.

Figure 2: System boundaries for the life cycle assessment of an IVF, including inputs, outputs, of the system.
Based on Martin et al. (2022)
The definition of system boundaries should also be set. This includes what is to be included
and what is to be omitted. Ideally, the system boundaries cover the full life cycle, with both
upstream and downstream inputs and outputs, including all material, energy, and
processes. However, often simplifications are done in order to match the scope of the study
and reduce the complexity. In the LCA field, the system boundaries are typically referred to
as being e.g. a cradle-to-gate study versus a cradle-to-grave study
2
. Cradle-to-gate
assessments include all inputs and processes up to the availability of a product at retail or
availability at the consumer. Cradle-to-grave assessments include the same as the cradle-to-
gate studies but also include the use and waste management of the product after
consumption, e.g., the waste handling methods for the growing media and packaging.
Figure 2 illustrates an example of the system boundaries for a cradle-to-gate and a cradle-to-
grave perspective applicable for an IVF. Note that the waste handling from the farm is
included in the cradle-to-gate boundaries and that retail is often not included. However, the
‘gate’ can also be extended to include the availability of the product at the retail location,
but not the use and final disposal of the product. This should be clear in the system
boundaries of the study. Typically, the retail phase for food products has only a minor
contribution to the environmental performance compared to other processes along the life
cycle and is often omitted given this motivation.
2.1. Life Cycle Inventory
The life cycle inventory (LCI) is used to collect data necessary for the quantification of the
environmental impacts of the service or product. This is done by mapping the applicable
material and energy flows and processes involved along the life cycle confined within the
system boundaries set in the scope of the project.
2
In agricultural LCAs, cradle-to-gate can also be referred to as ‘farm-to-gate’ and the cradle-to-grave
approach, referred to as a ‘farm-to-fork’ assessment.

For IVFs, data collection includes all material and energy inputs, all transportation
requirements, processes, infrastructure, and processes required for cultivation and waste
handling. Figure 2 above outlines many of these for a typical IVF. This is often the most
tedious part of conducting any LCA, and will require a number of iterations between the
LCA practitioner and the IVF, i.e. if the LCA is performed by an external source.
In order to alleviate the data collection, especially for IVFs, often a timeframe is chosen to
collect data, e.g., based on annual production
3
figures. For the LCI, data quality issues can
also be noted. For example, data should be as accurate as possible. Nonetheless,
assumptions may need to be made when the availability of accurate data is limited, which
may require a sensitivity analysis later in the assessment to see the influence this has on the
results. When assumptions are made by the LCA practitioner, these should be reviewed by
the IVF representative involved with the LCA in order to assure the assumptions are
realistic.
2.1.1. Material Inputs
For IVFs, a number of material inputs, or consumables, are required. Depending upon the
system, this can include all consumable inputs such as, packaging for inputs (e.g.,
cardboard, plastics, etc.), growing media, water, fertilizers, pH control, protective wear,
seeds, CO
2
enrichment, cleaning supplies, other chemicals, and packaging for products
(including pots, outer wrapping, cardboard, plastics). For some materials, there may be
more thorough data available. Assumptions can be made and documented on the amounts
employed based on the total outputs. Practically, it may also be possible to review expenses
and make estimates on the amounts used annually.
2.1.2. Energy
For IVFs, the energy demand is of key importance to the environmental impacts. As such, it
is crucial that data is collected on the amount of energy employed, in addition to its
sourcing. For electricity, information on the source are important for the LCA, and relevant
information on certificates of origin for the electricity should be reviewed.
Energy consumption may be primarily related to electricity demand for LED lighting,
pumps, HVAC
4
systems, monitoring equipment, and other processes. If external heating
sources from other energy carriers than electricity are used, these should also be included in
the study, e.g. natural gas or district heating.
2.1.3. Transportation
For the life cycle assessment, information on the transportation distance of all materials into
the farm, and products and waste leaving the farm, are included in the assessment.
Important information here includes the distances from the sourcing of the materials and
supplies. While detailed information can be included, assumptions can be made on the
distances. Furthermore, for transportation of the products to markets, a breakdown of
different markets can be provided, or an average travel distance could be provided.
3
It is recommended to conduct the study using annual values if a screening of impacts from the system
are to be done. If the production, and energy demand are consistent, a monthly value may be used. If
more details on how to improve seasonally are required, monthly data can be important.
4
Heating, ventilation, and air-conditioning (HVAC).

For LCAs, transportation of materials and products are typically assessed as tonne-
kilometers (tonne-km) as the LCI datasets for transportation logistics are provided in these
units. As such, the distance is then multiplied by the mass (in tonnes) of the material or
product. See, e.g., the row ‘Transportation-Inputs’ in Table 1, which sums up all the tonne-
km for all material inputs; similarly this is also done for the outputs and infrastructure. If
transportation of items to and from the farm are conducted in other forms, datasets, e.g. for
driving a car or van, can also be included, and are typically related to the amount of
kilometers driven.
2.1.4. Infrastructure
Infrastructure for IVF is an important input in the assessment of the system. For an IVF, this
can include steel structures, tanks, tubing, pumps, electronics, machinery (seeding,
packaging, etc.), HVAC equipment, LED armatures, etc. It is also important to take into
account the lifetime of the infrastructure. As such, the entire infrastructure does not affect
the environmental impacts of the vertical farm on one specific year but is distributed over
the lifetime. An example is the assumed steel structures which have a long lifetime. As 1500
kg of steel are assumed to be included in the structure, with a lifetime of 25 years, the
impact for the annual system would be related to employing 60 kg steel. The infrastructure
also may have varying durability, i.e. associated lifetimes. While steel structures may have
an assumed long lifetime, LED lighting fixtures and other active equipment, such as pumps,
tubing, and various plastics may have a much shorter lifetime due to their active use.
Maintenance and added equipment and infrastructure can also be included if the
information is available. The LCA practitioner and the IVF firm should make assumptions
on the lifetime of all infrastructure based on evidence from both practical experience,
information from the producer, scientific literature, and ensure to document this in the
study.
Table 1: Simplified input-output table employed for the LCI in LCAs of IVFs. Values are arbitrarily included.
Type
Category
Specific
Category
Inputs
Amount
(annually)
Unit
Transport
Distance
(km)
Inputs
Material
Inputs
Growing
Medium
Growing Media
10
kg
100
Fertilizers
Fertilizer 1
1
kg
50
Fertilizer 2
2
kg
50
Seeds
Seeds
5
kg
100
Water
Tap Water
100
m3
-
Other
CO2 (enrichment)
60
kg
45
Packaging
Polystyrene (PS)
3
kg
50
PET
5
kg
50

Polypropylene
5
kg
50
Cardboard
20
kg
50
Transportation-
Inputs
Material Inputs
(Truck)
6
tonne-
km
-
Energy Inputs
Electricity
5 000
kWh
-
Heat
1 000
kWh
-
Outputs
Production Outputs
Plant (Type 1)
400
edible
kg
50
Plant (Type 2)
500
edible
kg
20
Cultivation and
Packaging Wastes
Packaging Waste
(Plastic)
5
kg
50
Packaging Waste
(Cardboard)
15
kg
50
Organic Waste
10
kg
50
Transportation-
Outputs/Market
Market (Truck)
30
tonne-
km
-
Waste Handling
(Truck)
1.5
tonne-
km
-
Infrastructure
Infrastructure
Steel Tray
Structures
1 500
kg
100
Plastic
50
kg
100
Pipes
(Polyethylene)
15
kg
100
LED light fixtures
50
units
@ 1.5
kg
100
Tanks
2
units
100
Seeding Machine
1000
kg
100
Other Electronics
25
kg
100
Transportation-
Infrastructure
Truck
359
tonne-
km
-

2.1.5. Outputs
While some producers specialize in a single or a handful of outputs, others may have a large
span of different products. These can be accounted for differently, depending on the type of
outputs (e.g. salad, herbs, mushrooms, etc.). Furthermore, while some farms may sell
harvested crops, others may sell as potted plants with packaging and growing media. As
such it is important for an LCA to take into account the type of product sold. Typically this
is done by accounting for the edible portion, e.g. in kilograms, of the product to retail. For
potted plants, the total number annually can be used. Furthermore, waste from the farm
should also be accounted for, see subsequent section.
2.1.6. Waste Handling
Besides the edible portion of the products sold to market, there may be a number of waste
and residual streams produced from the farm. This includes, but is not limited to, biowastes
(e.g. growing media and plants), packaging wastes, wastewater to drain, equipment, and
any other consumables (e.g. protective wear). For each of these flows, the amount and their
method of waste handling should be accounted for. The waste handling methods for
different waste streams may vary depending upon the location and IVF. This can include
sending the waste for incineration, landfill, or to recycling for certain materials. If residual
streams are included in the output, and e.g. products or energy sold to other systems, these
are important for the life cycle assessment. This can include residual heat which may be
used in other applications, e.g. heating of the host building and other co-located spaces
(Martin et al., 2022).
In studies with a cradle-to-grave perspective, an important aspect to take into account is the
waste handling of the final product and packaging. As such, the materials and design of the
packaging may be important at this stage. Once again, methods for the treatment of these
waste flows should be accounted for. Practically, after the product leaves the farm this may
not be clear, as information on consumer behavior, including how they employ the product,
the share of waste, and what they do with the waste may not be available. As such,
assumptions can be made based on local conditions and systems available in the region.
2.1.7. Connecting to LCI Datasets
Once the inventory is complete, life cycle inventory (LCI) data is gathered to match those
flows and processes. Despite the comprehensive nature of LCI databases from sources such
as Ecoinvent (Frischknecht et al., 2005) not all datasets are available to match with flows and
processes outlined in the inventory. As such, representative datasets can be chosen,
although assumptions should be documented. For example, there may not be datasets
available for a specific component, e.g., a specific sensor. However, a dataset specifying an
‘active electronic component’ may be used as a proxy. At this stage, it is important to ensure
that the LCI datasets and the inventory listing have similar units. As an example, in the case
of the sensors, in the inventory, the number of sensors may be included. However, the LCI
data may be provided for the mass of the electronic components, e.g. in kg. As such
conversions will be required to allow for these to be used. When conducting an LCA, it is
important to always list which LCI datasets we used, which is often listed as a table, in
order to improve transparency.

2.2. Life Cycle Impact Assessment
The next phase of conducting a LCA is the life cycle impact assessment (LCIA). In this
phase, the environmental impacts associated with all inputs and processes are quantified
and provided for different selected environmental impact categories. When conducting this
phase, predefined LCIA methods included in LCA software are employed. These are used
to aggregate the environmental impacts into different environmental impact categories.
LCIA methods are categorized as midpoint and endpoint approaches. Firstly, midpoint
approaches provide quantitative modeling for equivalent emissions of substances. It stops
at this point to reduce the uncertainties and does not include weighting. Examples of
midpoint categories are global warming potential (kg CO
2
-eq.) or acidification potential (e.g.
measured in kg SO
2
-eq.). Taking this a step further, endpoint approaches model damages
caused by the release of different substances and emissions. An example of an endpoint
impact includes the Disability-adjusted life years (DALY) impact category which takes into
account years lost to premature death due to illness, disability, or early death. For IVFs, the
midpoint methods are most appropriate. As an example, for the impact category, Global
Warming Potential (also referred to as carbon footprint), an aggregation of all greenhouse
gas emissions (such as CO
2
, CH
4
, N
2
0, etc.) is conducted to assess their impacts on climate
change. These are expressed as kg CO
2
-equivalent units, denoted as kg CO
2
-eq.
While it is often assumed that carbon footprints are LCAs, this is only one impact category
in a much broader set of environmental impact categories. Various LCIA methods contain a
large number of impact categories. Some of these included the ReCiPe method (Huijbregts
et al., 2016) or the ILCD Environmental Footprint v. 3.0 method (ILCD, 2010) with a large
range of environmental impact categories available. The ReCiPe method contains 18
environmental impact categories, including; agricultural land occupation (m
2
a), climate
change (kg CO
2
-Eq), fossil depletion (kg oil-Eq), freshwater ecotoxicity (kg 1,4-DCB-Eq),
freshwater eutrophication (kg P-Eq), human toxicity (kg 1,4-DCB-Eq), ionising radiation (kg
U235-Eq), marine ecotoxicity (kg 1,4-DB-Eq), marine eutrophication (kg N-Eq), metal
depletion (kg Fe-Eq), natural land transformation (m
2
), ozone depletion (kg CFC-11-Eq),
particulate matter formation (kg PM
10
-Eq), photochemical oxidant formation (kg NMVOC-
Eq), terrestrial acidification (kg SO
2
-Eq), terrestrial ecotoxicity (kg 1,4-DCB-Eq), urban land
occupation (m
2
a), water depletion (m
3
water-Eq).
LCAs of IVFs may choose to include all or a selected number of environmental impact
categories. However, for IVFs, several authors have shown that important indicators from
LCIA methods include those related to carbon footprint, resource consumption, water
depletion, ecotoxicity, acidification, and eutrophication (Dorr et al., 2021; Martin et al.,
2022). LCIA methods, however, are regionally specific. Many of the LCIA methods are
based on European Conditions. As such, regionally specific LCIA methods for different
regions can also be used. For example, the ILCD or ReCiPe methods can be used for
European conditions, while the TRACI LCIA method is more applicable to North American
conditions.

2.3. Partitioning of Environmental Impacts in Multi-
functional Processes
If an IVF produces several products, referred to as a multi-functional process, the allocation
to the functional unit and other products from the system is necessary. The impacts are
therefore partitioned to all products of the system, which is done by physical or economic
allocation. Physical allocation is done by partitioning impacts to the different products by
their physical properties of the overall output, e.g. by their mass or energy. For IVFs, the
mass of the products is primarily used, with edible mass preferable. Economic allocation
refers to partitioning impacts to the products based on their economic value (e.g. market
price). The economic value inherent in the products and by-products may change, or be
different depending on the location of an IVF, inhibiting comparisons (Cherubini, 2010; van
der Voet et al., 2010).
In the ISO standards, it is recommended that allocation be avoided if possible (ISO, 2006).
To do so, a method referred to as system expansion may be used to avoid allocation, by
removing impacts from conventional products replaced from by-products of the system
(Weidema, 2001). This is done by identifying the equivalent amount of conventional
products or materials replaced by a by-product of the system and thereafter finding the
environmental impacts of producing that product. In the calculations, the impacts from the
avoided system are credited. The system expansion method is a form of consequential
modeling, also referred to as partial-consequential modeling (Brander et al., 2009), for the
avoidance of processes created in the system affecting markets outside the system (Zamagni
et al., 2012).
An example of this can include a mushroom farm, which produces mushrooms as the main
outputs, but the spent mushroom substrate is used for soil amendment. Assuming that
replaces, e.g. peat, the equivalent amount of peat, either in kilograms of volume (m
3
) can be
avoided and credited to the mushroom farm. See examples of such calculations for IVFs in
Figure 3 and also in previous assessments of IVFs including by-products that provide
credits to the system such as the use of residual heat from IVFs (Martin et al., 2019; Martin et
al., 2022).
Figure 3: Depiction of system-expansion method to depict how the use of spent mushroom substrate (SMS) can
lead to avoided peat use

It should be noted that the allocation in multi-functional processes is a highly controversial
topic in the LCA field. There is extensive literature devoted to this (see e.g. (Ekvall and
Finnveden, 2001; Wardenaar et al., 2012). Nonetheless, as Guinée et al. (2004) suggest, there
is no “correct” way to solve this problem in practice or theory. It should be apparent, that
the chosen allocation method is consistent with the research questions addressed and the
main methodological choices made. One way to avoid critique on the allocation issue is to
conduct the study and illustrate the results by applying different approaches, i.e., including
allocation (e.g. mass or economic) and system expansion, thus showing the influence this
can have on the results.
2.4. Interpretation
The ‘last’ phase of an LCA is the interpretation phase. In this phase, the practitioner(s)
interpret the inventory and impact results in order to assess the consistency, sensitivity and
significant issues to be used to formulate conclusions, recommendations, and limitations for
the study. This is important for communication with external parties in order to highlight
any limitations and uncertainties.
The process of interpretation is rather iterative in nature, requiring revisions to the model
and data. A previous study by Lazarevic (2012, page 3) describes the iterative nature of
conducting the LCA as follows, “the goal and scope of the study are defined, a life cycle
model is developed, impact assessments produced, the goal and scope are then refined or
revised if necessary, key data improved, impact assessment characterization factors are
improved, results interpreted, reported and subjected to independent review if necessary.”
For LCA studies with IVFs, this may include reviewing the assumptions made on different
processes, transportation distances, representative datasets employed, and making any
necessary improvements to the model. Processes, inputs, and datasets which were found to
have a large influence on the overall environmental impacts can also be analyzed further
and sensitivity analyses can be conducted to show their influence. This is often done by
changing the datasets, or showing how an increase or decrease in the specified amount can
influence the results. As outlined below, for IVFs, one important aspect to conduct a
sensitivity analysis is the electricity data employed.
3. Strengths and Limits of LCA for IVFs
LCA’s strength lies in its comprehensive approach to evaluate upstream and downstream
flows of a product or service (Hermann et al., 2007; Finnveden et al., 2009). This is
important, as impacts from a product or service may have impacts unevenly distributed
along the life cycle. For assessing the environmental implications of a product or service,
LCA cannot completely be replaced, as other stools may not review a cradle-to-grave
perspective (Finnveden, 2000).
However, LCA also has some limitations. The objectivity, methodological considerations,
and completeness have been debated for decades (Arvidsson et al., 2018; Freidberg, 2014;
Heiskanen, 1999). As previously outlined, allocation and other methodological choices have
been subject to extensive scientific discussion in the field (Brandao et al., 2017; Ekvall and

Finnveden, 2001; Plevin et al., 2014). Data availability can also be a limiting factor for
conducting LCAs of IVFs, with limited data on specific materials and infrastructural
components, e.g. substrates and components for the infrastructure.
LCA is also limited to environmental impacts. As such, it may be difficult to capture the
benefits of IVFs for local food provisioning compared to conventional methods. Despite
this, similar assessments can be made to assess the social and economic implications using
other life cycle approaches, such as social life cycle assessment and life cycle costing. These
can even be combined to provide a more holistic approach to assessing sustainability, using
life cycle sustainability assessment (Sala et al., 2013; Zamagni et al., 2013). Furthermore,
LCAs may not fully model rebound effects and future changes in technology, e.g. the claims
by IVF firms that it ‘frees’ space for conventional agriculture.
4. Insights from LCAs of IVFs
From previous studies applying life cycle assessment to IVFs, a number of processes and
parameters are important, or sensitive, for the overall environmental performance. The
following sections outline several of these important processes and parameters in order to
provide information that can be used to improve the process and environmental
performance for LCA practitioners and IVFs.
4.1. Electricity and Climate Control
Similar to other forms of controlled environment agriculture, energy is of utmost
importance for IVFs. From previous research, the largest share of environmental impacts
from IVFs has been found to stem from energy demands for LED and HVAC systems, see
e.g., findings in (Graamans et al., 2018; Martin et al., 2022; Weidner et al., 2022).
Additionally, given the large share of emissions from energy sources, the results are highly
sensitive to the source, and subsequent choice of LCI dataset, for electricity. It is advised
that when conducting an LCA for IVFs, the regional energy mix, or mixes, should be used.
As an example, Martin et al. (2019, 2022) show the sensitivity of employing the Swedish
electricity mix versus a Nordic electricity mix on the environmental performance of an IVF,
confirming significant differences between the two options.
Furthermore, if an IVF purchases electricity with certificates of origin, e.g., from
hydropower or wind, this should also be compared with the regional system. This is
exemplified in a recent study for IVF in Sweden, where the choice of hydropower-based
electricity led to lower environmental impacts compared to other studies from Sweden, see
e.g., (Milestad et al., 2020). As identified by Brander et al. (2018), it is not certain that the
electricity is produced from their claimed origins or can lead to changes in the electricity
mix of a given region or that the electricity used has the same profile. Additionally, different
standards for conducting LCAs handle the use of energy sourcing differently, and it is
advisable to show results based on different electricity sources and mixes in order to avoid
criticism. In conclusion, it is advised when conducting an LCA to show the sensitivity of
different electricity mixes on the results of the study.

4.2. Substrates
For IVFs, the choice of substrate can also have a significant influence on the environmental
performance of an IVF. Previous research has shown that substrates such as perlite and peat
may have large environmental impacts, while lower environmental impacts are found for
by-products such as coir (Martin et al., 2019; Martin et al., 2022; Quantis, 2012; Toboso-
Chavero et al., 2021; Vinci and Rapa, 2019). The use of peat also continues to be
controversial (Chapman et al., 2003; Hojlund, 2008; Salomaa et al., 2018). However, further
research should be conducted on the environmental performance of different substrates as
the use of new materials evolves for applications in IVFs. These typically include blends of
materials and there has been an increased influx of new substrate materials specifically
designed for IVF applications.
Depending on the growing system adopted, the amount of substrate needed by the IVF may
also significantly vary, or may even be absent (e.g., when aeroponic farms are using
reusable sowing mats, obtained from recycled materials). Accordingly, strategies that
account for substrate use reduction should also be envisaged, when comparative scenarios
are elaborated.
It should also be noted that the inherent properties of different substrates may also affect
their waste handling methods. For inorganic substrates, landfilling or incineration may be
the only option, while for other bio-based materials, composting or recycling may be
employed. This can also have an influence on waste management and should be considered
in the design of the system, e.g., to promote more closed-loop or circular systems.
4.3. Infrastructure
The infrastructure has been shown to have a minor contribution to the overall
environmental performance of IVFs. However, the infrastructure can contribute to as high
as 10-15% of the overall GHG emissions, and equally contribute significantly to resource
depletion, given the amount of metals and electronic components (Barge, 2020; Martin and
Molin, 2019). This can be sensitive to the assumed lifetime of certain inputs and
components. For example, as the industry is novel, there may not be a large base of
experience to base assumptions on the lifetime of products. Creating new buildings for an
IVF may have a large influence on the impact of the infrastructure, while employing
residual or existing spaces may not require as many resources. However, the materials and
processes needed to use existing spaces should also be taken into account. Again, for new
structures or intermediate processing required to use residual and existing spaces, the
assumed lifetime can have a large influence on the impact of the infrastructure. This
suggests that, from a life cycle perspective, choices to improve the lifetime of the materials,
have a benefit to the environmental performance of IVFs.
Furthermore, in previous assessments, the results were also found to be sensitive to datasets
for the infrastructure, including, e.g., electronics, machinery, and metals (Barge, 2020). For
infrastructure, it is crucial to carefully choose representative products in the LCI datasets.
Additionally, for reviewers of the LCAs and for ensuring the scientific-based information
provided by an LCA, transparently providing information on the assumed lifetimes in
addition to the LCI datasets employed is of utmost importance for an LCA.

4.4. Packaging
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. GHG emissions and resource
consumption). Reducing the amount of material, e.g. plastics, and developing approaches to
switch from conventional black-colored
5
plastics to other colors, or other bio-based
materials, may allow for the possibility of recycling and composting. This is also regionally
and context-dependent on the markets for IVF products. As such, the packaging should be
carefully chosen as it can also influence its waste handling methods. Further studies are
needed to understand this impact, especially as the IVF industry has been quick to address
the use of plastics in their work with sustainability.
5. Life Cycle Management and Increasing
Transparency
A large focus in the IVF industry has been geared to promote sustainability, although there
is little documentation on how vertical farming companies work with sustainability beyond
claims provided on the packaging and in media. For IVFs, it is important that claims made
are substantiated. However, few transparent assessments and studies of their work are
available; see e.g. (Agritecture, 2022). In previous research, it was found that IVFs consider
environmental performance information important for benchmarking and communicating
their environmental performance. However, few were willing to publicly provide the
results of their assessments due to the fact that most systems are constantly improving and
evolving. As such, the so-called ‘snapshot’ with an LCA may not be representative of a
system in the near future. Claims and comparative assertions on the benefits of IVFs
compared to conventional systems also contradict the original intent in the early
development of LCA, making comparative assertions and suggesting one system is better
than another. When drawing conclusions from LCAs, Finnveden (2000) suggested that
conclusions cannot be made on which system is "better," though they can lead to decisions
leading to a better course of action than would have been followed.
Using the information, however, can be essential to developing improvement options.
However, developing prospective approaches can be a beneficial stance to proactively work
with sustainability issues at an early stage of development to identify the best technologies
for specific contexts, e.g., markets, geographic locations, and infrastructure available
(Arvidsson et al., 2018; Martin et al., 2021).
6. Outlook and Improvement Potential
The majority of current vertical farming systems employ linear approaches to their
production. This entails that they employ imported (often virgin) materials from outside
5
Black plastics are often difficult to recognize in sorting systems and often end up in incineration

their immediate regions for all their resource and energy demands. In the future, employing
recycled materials in addition to renewable and residual energy sources may reduce the
environmental impacts of the consumables and other inputs. With cities becoming an
important driving force for the circular economy and as a critical stakeholder for developing
and improving food security, synergies between IVFs and their urban infrastructure are
essential for understanding and planning for future urban food systems. As such,
sustainable solutions for more integrated food, water, energy, and transportation will
become increasingly important (Specht et al., 2014; Martin et al., 2019; 2022; Rufi-Salis et al.,
2020). There is currently a number of research projects exploring such developments
ongoing worldwide, which have the potential to develop more circular approaches for the
IVF industry and potentially improve the environmental performance of IVFs.
Furthermore, in the coming years, it is expected that IVF production will gain in terms of
product diversification, moving from the current systems, which are mainly based on leafy
vegetables, herbs, and microgreens, toward a wide range of agricultural goods. In the
future, these are expected to include berries, edible flowers, potted seedlings, etc. For these
products, comparative assessments versus conventional production systems (both in terms
of cultivation and transportation/storage), may become more relevant to compare the
implications of IVFs.
Acknowledgments
The research leading to this publication was co-financed by the following funding sources:
1) Swedish Innovation Agency (Vinnova), within the Research Program, Innovations for a
Sustainable Society, in the project “Urban farming for resilient and sustainable food
production in urban area”’, grant code: 2019-03178, 2) the Swedish Research Council for
Sustainable Development (FORMAS), within the Research Program, Increased mobility
between academy and practice project “Assessing and Improving the Sustainability of
Urban Vertical farming Systems,” grant code: 2019-02049, and 3) the Italian Ministry of
Research and Education (MUR), within the Research Programmes of National Interest
(PRIN) project “Sustainable Vertical Farming (VFarm),” grant code: J33C20002350001.
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