Comparing the usefulness of assessment tools for
environmental impacts evaluation of organic greenhouse
L. Foresi1a, A. Antón2 and U. Schmutz1
1Centre for Agroecology, Water and Resilience (CAWR), Coventry University, Coventry, United Kingdom, 2Institut
de Recerca i Tecnologia Agroalimentàries (IRTA), Cabrils, Barcelona, Spain
Organic farming is primarily meant to be sustainable; however, evaluating the
sustainability of farming systems in a complete way is a complex issue. In recent years,
a high number of sustainability assessment tools has been developed and used
worldwide; nevertheless, even if they differ in terms of analysis depth, none of them
seems comprehensive enough. Amongst all the existing tools we have chosen two of
them, Life Cycle Assessment (LCA) and Public Goods Tool (PGT). In the case of specific
farming systems such as organic greenhouse horticulture, a comparison between LCA
and PGT has been done to evaluate the potential integration between both sets of
results so that a single holistic assessment method could be obtained. This could help
to understand which sustainability aspect these methods should focus on and which
type and depth of data would be desirable. This paper mainly highlights the
methodological differences and potential common points between the tools, referring
to a chosen case study (Tolhurst Organic, a stockfree horticultural unit located near
Reading, UK) that has been assessed with both, and then gives suggestions for future
research. An updated and improved version of the LCA Excel tool, initially developed
by the EUphoros project (2008-2012) and then integrated with data from PGT, was the
main outcome of the comparison. While LCA gives quantitative results on impacts on
key environmental categories, PGT shows ways to improve farming practices
regarding a set of social, economic and environmental aspects through a simple scoring
system. In this sense, trying to combine results from different assessment tools might
be difficult because it highlights the lack of overall complementarity between them, but
at the same time it could be a useful starting point for an integrated discussion on
production, use of natural resources and improvements of practices among decision-
Keywords: organic farming, vegetable production, protected crops, sustainability evaluation,
life cycle assessment, public goods
Organic agriculture assumes a central role in producing healthy food while avoiding
excessive negative impacts on the environment.
Among the different farming systems, horticultural productions are major contributors
to food production since fruit crops and vegetables are both integral constituents of a healthy
human diet. However, even within the organic framework, they often are more intensive in
a E-mail: firstname.lastname@example.org
terms of labour and used inputs (Raviv 2010), especially if crops are grown inside protected
Globally, a core concept in organic protected horticulture is the development of more
environmentally friendly applied techniques and technologies (i.e. advanced structures and
growing methods), capable of facing resources shortage and increasing request for high
Growing crops in greenhouses has raised contrasting views among experts because on
one hand, this system protects the plants from external agents and extends the living cycle of
the crops, potentially improving their quality and allowing higher yields, not to mention
providing products all-year round (Pardossi et al. 2004; Simson and Straus 2010). On the
other hand, it is argued that protected horticulture requires a huge amount of energy and
generates large quantities of wastes (Vox et al. 2010).
Nowadays, there is a lack of specific rules for this specific production system, so
practices might differ widely from country to country; at the same time, there is a need to
keep true to organic agriculture’s basic principles specified in the regulations (i.e.
maintenance of biodiversity and fertility, management of soil and crop health, rational use of
The European Union is also currently lacking reliable data on areas devoted to organic
protected vegetable production; according to Tittarelli et al. (2014), it is estimated that
approx. 4,500-5,000 ha of greenhouses are effectively managed organically within the EU.
Agricultural systems, especially organic greenhouse productions, are faced with
changes triggered by population dynamics, global market forces, investments, advances in
science and technology, climatic variability, consumers’ demands, subsidies, social
movements demanding food sovereignty, land reform and reduction of poverty. Identifying
indicators to show performance, especially at farm level, uncover specific management
problems, or highlighting unwanted impacts, and what action to take, is a major task, for the
focus of change in practices is to improve the overall long-term health of farm businesses
(Koohafkan et al., 2011).
On this note, it is recognised that there is a general lack of assessment tools focused on
evaluating sustainability performances of organic protected production. In the case of organic
greenhouse horticulture, assessing sustainability performance is a complex matter, for it is
far more intensive than any other farming system. However, it is considered a key production
system for the future, given the physical protection from the changing environmental
conditions it provides to crops at any latitude.
This could open the way to possible on-farm data collection throughout the European
Union either using existing tools (i.e. OCIS PG tool, Gerrard et al. 2011; LCA, U.S. EPA 2006) as
references, or setting the foundations to develop new targeted methods to find suitable
indicators for protected horticulture, and potentially create a standardised and adaptable
system for performance evaluation of organic greenhouses in Europe.
MATERIALS AND METHODS
The main objective of this work was to compare different assessment tools and then try
to evaluate the possibility of integration between them, so that a single comprehensive tool
could be obtained, since there is no specific method to “measure” sustainability in organic
The first and main phase of the work has been focused on updating a simplified version
of an environmental simulator, which was developed as an LCA Excel-based worksheet
through the EUphoros project (2008-2012).
The LCA worksheet was updated expanding the set of available crops, reviewing both
impact categories and characterization factors, and recalculating the data contained in the
database, with the support of the SimaPro 8 software (i.e. addition of data on greenhouse
structure materials and consequent emissions to air, water and soil).
The integration of LCA’s initial data with those from PGT’s worksheet has been
evaluated and attempted and from a theoretical point of view, main drawbacks and possible
improvements for both tools have been identified as a result.
Data collected during the assessment carried out in March 2015 at the farm used as
“case study” (Tolhurst Organic, a stockfree horticultural unit based in Hardwick, Reading, UK)
has been transferred into the LCA worksheet, to have a further example of its practical
application and a means of comparison between the outcomes of the two methods.
The Case Study: Presentation
Tolhurst Organic Partnership C.I.C.b is based at the Hardwick Estate, just outside the
village of Whitchurch-on-Thames, South Oxfordshire, UK, with 17 acres (approx. 7 ha) in two
fields and 2 acres (approx. 1 ha) in the 500-year-old walled garden.
It is one of the longest running organic farms in England, holding the Soil Association
certification and having been the first one to obtain the Stockfree Organicc brand in 2004. Iain
Tolhurst is one of the founder members of the Thames Organic Growersd and has registered
as a Community Interest Company in May 2014. It was also the first farm to be part of the
Vegan Organic Network (VON)e, which produced the world’s first set of stockfree organic
The farm produces high quality, locally available, organically grown food without using
animal inputs (i.e. less land used, lower carbon footprint and energy requirements). In this
case, soil fertility comes primarily from fertility building crops and well-designed rotations.
In an average year, Tolhurst Organic produces at least 85% of the value on its land and
delivers fresh in-season vegetables and fruit through the Neighbourhood Rep Scheme, which
runs the drop-off points.
According to Tolhurst, the farm grows 300 different crops, considering both species and
varieties of vegetables, all-year round on approximately 6.5 ha of land, comprehensive of the
fields, the garden and the greenhouses within the wall, and it manages to supply fresh produce
for an average of 50 families per ha.
The farm is classed as an AONB (Area of Outstanding Natural Beauty), thanks to 500m
of hedges planted with mixed indigenous species and shrubs, and a total 1800m of hedgerows
that reduce pest attacks and keep a healthy balance of predators, without using any kind of
All the plants are grown on-farm (over 140,000 per year) and an average of 120 tons of
vegetables is directly produced and distributed yearly.
The farm also has a low energy storage system in the form of a well-insulated room,
mostly used for squashes and potatoes, where the temperature stays naturally at 8ºC.
There are also poly-tunnels on the farm, usually hosting lower-yielding vegetables (i.e.
tomatoes, cucumbers, carrots, and lettuces) and seedbeds, and covering a total area of 0.17
Since they represent a fundamental part of the farm management, a great care is put
into rotation plans, both out in the fields and between greenhouses, and green manures have
a dominant role in this matter. The farm uses a mix of 20 different crops as green manure,
most of them legumes, and one third of the rotational period is devoted to fertility building
(one year every 2.5-3). This way, green manures are present at all times keeping the soil
In terms of nutrient levels, it has been pointed out that leafy greens (i.e. kale, swede,
celeriac, etc), are grown during the winter for their high N content and that there is a general
K deficit, which could be solved by applying wood ash as a natural fertiliser.
An important point is the self-production and use of organic matter, which amounts to
roughly 250m3 per year (125 tonnes, possibly 4ha worth); all the organic waste produced on-
site is then recycled as compost.
The farm is also showing a growing interest towards agroforestry, in terms of wood
production and biodiversity management, and recently they have planted 7 acres (3 ha) with
strips of mixed native tree species (i.e. alder, willow, birch, maple, hornbeam, oak, wild
cherry) inter-planted with apple trees, which will be managed with short rotation coppice
and used for firewood.
As an added measure to maintain biodiversity, ecological structures such as beetle
banks, hedges and field margins are present and managed all around the farm, to serve as
refuges for natural predators and a source of food for wild animals.
In regards to irrigation, the farm uses a total of 2240m3 of water over a period of 20
weeks every year, and it accounts for most of the petrol used on farm because the water is
pumped from the aquifer.
In 2007, the total carbon footprint of the farm has been calculatedf and it is
approximately 8 tons, same as the average household in the UK, with the farm being 90%
more efficient than conventional supermarket products. In terms of consumptions, the total
energy goes on fuel for tractors, delivery vehicles, and other machinery (2030 litres year-1)
and electricity is used for lighting buildings, providing facilities for plant growing, and other
odd jobs (6400 units year-1).
RESULTS AND DISCUSSION
The Case Study: Results from PGT
Tolhurst Organic is a specialised horticultural enterprise, so it was difficult to single out
every cultivated crop and the related areas because the Public Goods tool has not been
designed for organic greenhouse horticulture. This might suggest setting up a separated Excel
worksheet, which would be created specifically for protected structures. Moreover, vegetable
yields and requirements could be assessed through splitting the crops between families.
The same could be done for green manures, since they are used as a mix and the areas
on which they are cultivated are limited, so it is difficult to make precise calculations.
As shown in Figure 1, the lowest scores of the assessment done via Public Goods tool
were registered for spurs like agri-environmental management (2.8/5) and water
management (1.8/5), mainly because of a lack of agreement with some of the schemes
currently in force (i.e. wildlife habitats, permanent pasture, conservation plan; joint character
area; water audit, management plan). In these cases, key aspects such as biodiversity
improvement and crop protection, are being managed in more alternative and sustainable
ways (i.e. natural structures, no use of pesticides, etc). The highest scores were registered for
fAudit carried out by Prof. Tim Jackson (BBC Climate Change Special, March 2007; source:
spurs like soil management (4.8/5), food security (4.8/5) and agricultural systems diversity
(5/5). Once again, green manures are an integral part of all the rotations, so that the soil is
never left uncovered. Moreover, an important part of the farm’s philosophy regards growing
local fresh produce, while minimising the use of external inputs, and all the vegetables
produced are sold to local families and communities.
A weak point for greenhouses would be the amount and disposal of plastic wastes, and
in this case Life Cycle Assessment could offer a more in-depth analysis.
Figure 1. Graphic representation of the final results of the assessment done via Public Goods
tool at Tolhurst Organic (March 2015).
The Case Study: Results from LCA
The total farm protected area amounts to 0.17 ha (1700 m2), and since the LCA Excel
tool considers different types of structures (i.e. multi-tunnel, glasshouse, parral, tunnel), a
multi-tunnel was chosen for the analysis, to be as close as possible to reality. Further
requested data comprises the dimensions of the structure, the materials used and their
related lifespans, the eventual use of mulching, and the transport of said materials.
The initial data sheet requires information such as fuel use, water employed for
irrigation, electricity consumption, and use of fertilizers, so data from the previous
assessment have been recalculated and proportioned to the farm’s protected area (Table 1).
Food security; 4,8
Social capital; 3,7
Table 1. Data taken from the assessment via Public Goods tool, recalculated to be
proportioned to the total on-farm protected area (1700 m2) then used for LCA. Both sets of
data refer to an average year of consumption.
Fuel usage (diesel)
Water for irrigation
The integration between the two sets of results has been attempted and it had
highlighted major drawbacks for the lack of overall complementarity between them. LCA
gives quantitative results on impacts on key environmental categories while PGT shows ways
to improve farming practices regarding a set of social, economic and environmental aspects
through a simple scoring system.
The comparison between assessments was only experimental given some main gaps
that were found, such as methodological dissimilarities between tools and lack of data for
reference in LCA’s case (Table 2; for more detailed results, see
However, the use of different methods to assess the sustainability performance of a
farming system would give stakeholders and decision-makers the chance to have an
integrated discussion on possible improvements (i.e. tangible data on productions and use of
natural resources and qualitative evaluation of farming and conservation practices).
Table 2. Total results of the case study via Life Cycle Assessment (supported by SimaPro 8
software; June 2015). Red and green cells respectively represent higher and lower values in
comparison to the references used during the analysis.
(per kg of tomatoes)
Climate Change (CC)
Resource Depletion (RD)
k Sb eq
Terrestrial Eutrophication (TE)
molc N eq
Marine Eutrophication (ME)
kg N eq
kg P eq
Particulate Matter (PM)
Water Use (WU)
Figure 2. Detail of results from case study via LCA. Contributions from each group of activities
(in %) are shown per impact category. In general, structure and fertilization are
the largest contributors to soil, water and air emissions for all the impact
Through the first stage of the work, an up-to-date and improved version of the LCA
Excel-based tool has been obtained, comprising the following parts:
Four main worksheets (i.e. Instructions, Input Data, Detailed Results and Total
A Database containing the default data, and an Inventory with all the information
needed for the actual assessment;
A set of basic impact categories (i.e. climate change, particulate matter, terrestrial and
aquatic eutrophication, acidification, resource depletion) that could function as a
starting point for future assessments of specific farming systems such as organic
greenhouse horticulture (i.e. possible future integration of categories such as land use
and biodiversity loss).
This Excel-based simulator would be used as a practical support to calculate the
environmental impacts of protected production systems and could be helpful for both
growers and advisors to compare different options in terms of efficient use of resources.
The presented case study has been evaluated with two different methods so far,
comprising both a general qualitative assessment of the farm sustainability and a range of
quantitative data on specific environmental impacts.
A few points for further research have been highlighted after the comparison:
The potential addition of social and economic aspects to LCA;
The integration of PGT with more specific data on organic greenhouse horticulture,
possibly through an extra Excel worksheet or a dedicated “spur”;
The collection of more data on organic farming (greenhouse horticulture included)
The implementation of local and/or regional databases for LCA, potentially through
representative case studies.
Also, some observations on both tools could be added to the discussion for further
The main difference between them is in the type of data they employ (i.e. exclusively
quantitative for LCA, mix of quantitative and qualitative for PGT);
Initial data collection is a long and complex phase in both cases;
The tools are both applicable to “industrial” farming systems (large productions);
LCA showed some difficulties for application to local situations/small farms;
Neither tool is dedicated to organic greenhouse horticulture, but could be
“modifiable” according to the needs of the analysis (i.e. choice of data as “specific” as
possible depending on the case, especially for LCA).
The work behind this paper has been done during a Short-Term Scientific Mission at
the Institute for Agrifood Research and Technology (IRTA), located in Cabrils (Barcelona,
Spain), between May and June 2015, as part of the EU COST Action FA1105 “Biogreenhouse”,
who has financially supported the Mission through a grant.
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