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Methods for analysis of physical impacts

Ecological Footprint

Short Version


Extended Version

Definition & Objectives

Ecological Footprint (EF) is a method to examine the area necessary to continuously provide for the standard of living of humans under current conditions of production. It may also be used in aggregate form to measure the impacts of current consumption patterns of communities, regions or countries. It is used primarily as a sustainability indicator for the purpose of monitoring activities and as a communication tool (Global Footprint Network).

A concise description of Ecological Footprint is given in a report to the European Commission (Best et al. 2008, p. 38):
EF measures how much biologically productive land and water area is required to provide the resources consumed and to absorb the wastes generated by a population, taking into account prevailing technology. More specifically, the six categories of productive areas are: cropland, grazing land, fishing grounds, forest area, built-up land, and carbon demand on land. Should the object of measurement (in most cases a nation) exceed the biocapacity of its region (the national area), experts talk of "ecological deficit" of this region. The opposite caseis called an "ecological reserve" (less consumption than biocapacity). Transferred to the global level, an overall ecological deficit is referred to as "ecological overshoot", which means that humanity has to make use of the natural asset base, the producer of biocapacity. The consequence of a longterm ecological overshoot is hence a degradation of natural capital.


One way to analyse the suitability of an IA method s the so called RACER analysis (Best et al. 2008, p. 27)  RACER stands for
Relevant (Which objectives can be fulfiled? Scope and level?)
Accepted (Opinion of different stakeholders?)
Credible (Suitable also for non-experts? How easy to interpret?)
Easy (What data collection is necessary? How much costs and ressources?) and
Robust (Is it immune against manipulation?)


An EF of a defined unit is suitable for monitoring resource use (e.g. as consequence of economic growth). It is mainly applied at the national level where it can make available a robust and transparent account of the pressure put on ecological services and resources by human activity. As such, it represents a method allowing for international comparison of a nation’s demands on the global regenerative capacity. Furthermore, EF is particularly helpful in communication of (non)-sustainable consumption trends and developments as well as direct comparison of different units with its results since it has a standard unit of measurement, the "global hectare" or gha (meaning a hectare with global average bioproductivity) (Ferretti et al. 2012, p. 65). EF basically addresses one specific research question: How much of  the biosphere’s regenerative capacity is occupied by given human activities? However, due this specific focus EF cannot measure all the specific impact dimensions of resource use (Best et al. 2008, p. 42f.).

Concerning the scope and level of EF, it was already mentioned that footprints on the national level are regarded as the most accurate and developed form of
Footprint calculation. However, an EF can also be applied at other geographical or administrative levels (e.g. for cities) and to single activities, products, persons, enterprises or industries.(Best et al. 2008, p. 49f.).


The EF is most popular to address a broad public, as it provides an easy way to communicate complex matters. This srenght on the one hand presents an disadvantage for other stakeholders: in particular representatives from statistical offices are critical of the method as being over-reliant on conversion
factors and imputations of missing data. Also, EF alone does not lead to immediate policy conclusions and hence is only then suitable for policy-makers if they wish to inform and thereby generate public's support on certain decisions. (Best et al. 2008, p. 51f.)


While the basic concept of the EF can be easily understood and its results clearly demonstrated and visualised (and therefore is mostly used to adress the public), the devil lies in the detail: Critics argue, for example, that EF calculations per country are rather arbitrary from an environmental perspective, that it is not intirely clear what is being measured, and how resources and waste are being converted or that EF makes no distinction between sustainable and unsustainable land use (van der Veen, A. 2006).


Institutionalizing the EF as a national sustainability indicator requires comprehensive statistical data and expertise. The Global Footprint Network's website publishes the National Footprint Accounts of 150 jurisdictions on the basis of United Nations’ source datasets on an annual basis. These national accounts build approximately on 6000 data points per country per year, from 1961 onwards. In recent years various calculators for quick footprint analysis as well as more sophisticated tools for integrated consideration of different footprints and other indicators have been developed to support footprint application (Čuček et al. 2012).




The basic calculation of an EF is simple: The demand for ressource production or for waste assimilation is translated into global hectares (ghas) by dividing the total amount of ressources consumed (D) by the yield per hectar (Y) or respectively dividing the waste emitted by the absorption capacity per hectare: EF = D (annual) / Y (annual)

Calculation of yields are provided by various international statistics, most importanly those from the UN Food and Agriculture Organisation's  (FAO) Resources STAT Statistical Databases. Important: Yields are always mutually exclusivein order to avoid double counting, meaning that, e.g., two crops growing on the same hectare each only get assigned a proportion of the hectare. Yields are expressed in global hectares, which are, in essence, estimated with the help of two factors: the "yield factors"(comparing national average yield per hectare to world average yield in the same land category) and the "equivalence factors" (capturing the relative productivity among the carious land and sea are types). (Ewig  et al. 2010)

Combination with other methods

EF can be part of a Life-Cycle Assessment of a product or process. In this context, the ecological footprint of a product is defined as the sum of time integrated direct and indirect land occupation, related to nuclear energy use and to CO2 emissions from fossil energy use: EF= EFdirect +EFco2+ EFnuclear (Goedkoop et al. 2008)

EF can give an answer to the question of indirect effects: How much are we directly and indirectly dependent on nature in our consumption and production?
This notion of dependence is closely linked tothe input−output analysis, therefore the EF principle has potential to be combined with this method (van der Veen, A. 2006)

Strengths & weaknesses

(+) EF provides an indicator that enables the comparison of resource use in different jurisdictions.
(+) Footprints reflect changes in resource use over time.
(+) It is a suitable tool to compare human demand against “carrying capacity”, an otherwise overlooked aspect.
(+) Results are easy to communicate, due to EF's didactic stregth

( - ) EF does not disaggregate impacts according to policy measures and hence is less suitable to support policy making
( - ) EF accounts do not contain spatially disaggregated data on actual land use and do not provide precise information on ecosystem impacts.


Best, A., Giljum, S., Simmons, C. et al. 2008. Potential of the Ecological Footprint for monitoring environmental impacts from natural resource use: Analysis of the potential of the Ecological Footprint and related assessment tools for use in the EU’s Thematic Strategy on the Sustainable Use of Natural Resources. Report to the European Commission, DG Environment.

Čuček, L., Klemes, J. J., Kravanja, Z. 2012. Review of Footprint analysis tools for monitoring impacts on sustainability. Journal of Cleaner Production 34, pp. 9-20.

Ewig, B., Moore, S., Goldfinger, A. et al. 2010.The Ecological Footprint Atlas 2010. Oakland. Global Footprint Network.

Ferretti, J., Guske, A.-L., Jacob, K., Quitzow, R. 2012. Trade and the Environment. Frameworks and Methods for Impact Assessment. FFU-Report 05_2012.

Goedkoop, M., Oele, M., de Shryver, A. 2008. SimaPro Database Manual. Methods Library. PRé Consultants.

Global Footprint Network Website

van der Veen, A. 2006. Ecological footprint (EF). Sustainability A-Test, Advanced Techniques for Evaluation of Sustainability Assessment Tools.



Osenstetter, E. 2013. Introduction to Ecological Footprint for Impact Assessment. LIAISE Toolbox



Life-cycle assessment (LCA)

Short Version

Life-cycle assessment (LCA) is a method to assess and evaluate the environmental impacts of a product, process or service, along their whole life-cycle, from raw material acquisition to its disposal. Environmental effects considered and quantified include resource use, human health, and ecological aspects. Based on this systematic consideration of products'/ processes' environmental performance decision-makers are enabled to make strategic choices and to stimulate improvements. LCAs are helpful in developing product or value chain oriented programmes (e.g. for eco-labeling of export products or developing strategies to improve the environmental performance of a particular value chain), process-oriented policies (e.g. regulating the use of hazardous materials in a production process) or waste management strategies (e.g. determining whether specific materials should be recycled or disposed of and what targets should be).

Standardized LCAs are carried out as relatively complex quantitative exercises. However, in recent years, less time and resource-intensive qualitative LCA methodologies have been developed. These ‘LCAs light’ are often conducted as Qualitative Matrix LCAs that can also be used as starting points for a complete LCA.

However, since LCA only focuses on the environmental impacts, it cannot provide other relevant information that must be taken into account by decision-makers (costs, performance, social impacts etc.). Also, it is a very time and resource intensive method and requires high expertise to be conducted.

Extended Version

Definition & Objectives

Life-Cycle Assessment (LCA) is an internationally standardised methodology. As an objective process it evaluates the environmental impacts associated with all the stages of a product's life "from-cradle-to-grave" (i.e. from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling). Additionally to this identification process, an LCA furthermore demonstrates opportunities to achieve environmental improvements. (ISO 14040 ff)

According to the Society of Environmental Toxicology and Chemistry (SETAC 1993, p.7), "[...] the prime objectives of carrying out an LCA are:

  • to provide a picture as complete as possible of the interactions of an activity with the environment
  • to contribute to the understanding of the overall and interdependent nature of the environmental consequences of human activities; and
  • to provide decision−makers with information which defines the environmental effects of these activities and identifies opportunities for environmental improvements."


An LCA enables decision-makers to select the product or process that results in the least impact to the environment. Other factors, like information on cost or performance, must however be evaluated seperately if they should be taken into account in the selection process, as an LCA does not provide these information. The unique selling point of an LCA is that it takes into consideration the whole environmental impacts of a product or process, by identifying their transfer from one life-cycle stage to another. If an LCA were not performed, the transfer might not be recognized and properly included in the analysis because it is outside of the typical scope or focus of product selection processes. (EPA  2006)

Specifically, governments and administrations can make use of an LCA in the following manner (Schepelmann 2006):

  • To support strategic choices regarding environmental performance of product, energy, transport, building and agriculture policies
  • As a a platform for exchanging environmental information, e.g. for covenants or permits
  • To supports ecolabelling
  • To to make consumers aware of their environmental behaviour

Importance of impacts:

LCA has emerged as a valuable decision-support tool for both policy makers and industry in assessing the cradle-to-grave impacts of a product or process.

Assessing impacts:

In the analysis of impacts, economic, social and environmental impacts should be adressed for each option. (European Commission 2009) Concerning these three dimensions, LCA focuses mainly on the environmental impacts of a product or process, while economic and social impacts are being less addressed. Therefore, an LCA is most adequate when the most significant impacts are identified as being environmental and hence an in-depth qualitative and quantitative analysis of these environmental impacts is neccessary.

Type of method:
An LCA can be both, a qualitative or a quantitative method. Standardized LCAs are carried out as relatively complex quantitative exercises. However, in recent years, less time and resource-intensive qualitative LCA methodologies have been developed. These "LCAs light"  can also be used as starting point for a complete LCA. So called integrated LCAs combine the quantitative and qualitative elements of the standardized LCA approach and "LCAs light". (SolidWorks 2012)

Complexity, costs and robustness:
According to BCorporation (2008), the price for conducting an LCA ranges from 8,000€ and 50,000€, depending on the scope of the assessment (i.e. consideration of the complete life-cycle of a product/process or only parts of it) and on the detail of the analysis (.i.e. consideration of all types of environmental impacts or only selected ones). Qualitative LCAs will be less expensive than full LCAs, as they do not require quantitative data. However, they both need professional expertise to be carried out.
"LCAs light" are less robust compared to the standardized LCA, but can be applied in the context of high-level decisions, and they are also useful for involving stakeholders, since they will be easier to understand for non-specialists.

How to apply the method

The main areas of the application of an LCA within public environmental politics have been waste treatment options, means of transport, energy sources, and product’s choice (Frankl & Rubik 2000).

The ISO standard series 14040 (ISO 2006) identified four main phases of an LCA:

1. Goal and scope definition | 2. Inventory Analysis | 3. Impact assessment | 4. Interpretation

While the first phaseshould be the task of the policy maker, the rest of the assessment is normally conducted by an expert (group), since these phases require high expertise and are normally very time and ressource consuming.

First phase: Goal and scope definition

First, the goal - the reason for carrying out the LCA - must be identified. In most cases, the primary goal of an LCA will be to choose the best product, process, or service with the least effect on human health and the environment, since this is what an LCA can achieve. Secondary goals can be:

  • Supporting broad environmental assessments
  • Establishing baseline information for a process
  • Ranking the relative contribution of individual steps or processes
  • Support for public policy
  • Support product certification
  • Provide information and direction to decision-makers
  • Guide product and process development

(EPA  2006)

Once the primary and secondary goals are identified, the scope of the LCA must then be adapted concerning its depth, breadth and detail so it will be able to adress the stated goal(s). The following questions help identifying the scope of the LCA:

  • What is the spatial and temporal scope of the LCA?
  • What are the functional units to be assessed?
  • Who is the target group?
  • Which decisions must the LCA support?
  • What is the extent of these decisions?
  • Which product/solution is to be assessed, and which alternatives to be compared?

(ISO 2006)

Second phase: Inventory analysis

Inventory analysis involves data collection and calculation procedures to quantify relevant inputs and outputs of a product/ process. The process of the inventory analysis is iterative, meaning that new insights about the analysed system might emerge during the analysis, so that the data requirements might have to be adapted to these new insights in order to still meet the goals of the LCA.

Third phase: Impact assessment

The results of the inventory analysis are allocated to different impact categories (like resources depletion, human health as well as ecological and global impacts). Then, these impact categories are operationalized by specific impacts such as contribution to the greenhouse effect, acid rain, the ozone hole, etc. This step involves (often implicitly) an assessment, on the one hand by the selection of impact categories per se and the other by the choice of emissions that are attributed to a certain impact category or not.

Fourth phase: Interpretation

The interpretation phase organises the results of the inventory analysis and impact assessment in a comprehensible way in order to handle them by decision makers. The findings allow a global view on the life-cycle of products or processes.

Combination with other methods

Schepelmann (2006) outlines possible combinations and interactions of an LCA with:

Types of data needed

Data can be acquired from industry data reports, databases (e.g. the European reference Life Cycle Database) consultants, government documents, reports or previous life cycle inventory studies. Furthermore, a broad range of LCA tools (software) and databases to support LCAs have been developed in recent years, the Joint Research Centre has listed a number of such tools in its LCA Info-Hub.

Strenghts & weaknesses

(+) Provides a holistic picture of environmental impacts and of the locus and intensity with which they occur within a value chain.
(+) Provides a basis for developing targeted policies at individual segments of a value chain.
(+) Allows comparison of the ‘environmental friendliness’ of two or more products/ processes.

( - ) Performing an LCA is often resource and time intensive and requires special expertise in this field
( - ) Data might be difficult to compile, although an increasing number of free LCA data bases and LCA software are aimed at simplifying LCAs
( - ) A standard LCA does not determine which product/process is the most cost effective or works the best; also, the social aspect of sustainability is less adressed by an LCA

Useful Links


BCorporation (2008)

European Commission 2009

EPA  2006

Frankl & Rubik 2000

ISO 14040

Schepelmann 2006

SETAC 1993

SolidWorks 2012


Quotation: Osenstetter, E. 2013: Introduction to Life-Cycle Assessment for Impact Assessment. LIAISE Toolbox. Available at:

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