Ecological Footprint Methods
Ecological Footprint analysis has been conducted at a various levels such as nation, region, sector, company and product. There are various methodologies followed to analyze the ecological footprint depending on many factors. This part of the report addresses the ecological footprint methods.
Prior to conducting ecological footprint analysis, there are certain fundamentals which need to be covered. These are pre-requisite before the application of the methods of footprint.
4.1 Data Availability
Data is one of the crucial factors for the Ecological Footprinting. The data needs to be scooped and checked and compared with other available data for the area where the analysis is to be conducted.
4.2 Boundary Definition
The boundary of the ecological footprint needs to be defined. The ecological footprint analysis faces boundary definition issues to include and exclude activities. There are two principles of defining a boundary of the study.
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4.2.1 Geographical (administrative) boundaries
This principle is based on whether the study should calculate footprints within the geographical or administrative border. For example, if the footprint study needs to be done for an airport in Germany, all the impacts due to the airport will be contributed to Germany by using Geographical boundary.
4.2.2 Responsibility boundaries
The responsibility boundary is based on the consumption of an area's population irrespective of where the consumption occurs. For the same example of airport, in this case, only the impacts which are attributed to people in Germany will be included.
Therefore, it is to be noted that the answers can be very different depending on the boundary condition we choose for our analysis to be conducted.
4.3 Double Counting
Double counting should be avoided as it would unnecessary make the footprints bigger. There are many steps during ecological footprint analysis in which there are dangers of double counting. To avoid double counting, the processes should be clear and well defined.
There are basically two methods to calculate the footprints. They are the compound or component-based methods which are explained in following sections.
5.1 Compound method
Compound Method is the top-down approach. The compound method is applied at the national level and utilizes trade data such as national production, import and export to determine consumption and calculate the footprint.
The procedure is mainly composed of following steps:
5.1.1 Consumption Analysis & conversion to area
Consumption analysis is conducted for biotic resources including meat, fruits, grains, dairy products so on. The consumption analysis is done for primary products and its derived secondary products.
Primary products are products which can be used directly or processed into secondary products like vegetables, unprocessed round wood etc. Consumption for primary product is calculated by production and adding imports and subtracting exports.
The consumption quantities are converted into land area by their corresponding world average biotic productivity, or yield. At the national level, world average productivity is used for each land type to create a common base yield for inter-country comparisons.
The consumption divided by the yield of that particular resource gives the area required to generate that consumption. The formula is given in slide 27 in annex 1.
It should be noted here that further adjustments should be made to avoid double counting where necessary. For the double cropping lands, consumption should be considered only once as it will increase the footprint area. If the animals are grain fed, resource meat should be converted to arable land and not pasture.
Secondary products are derived products like milk, paper etc. Secondary Products are converted into primary product equivalents for to calculate Ecological Footprint.
The global conversion figure is used for imports of secondary products use the global conversion factor whereas national conversion factor is used for domestically produced goods. The weighted proportion of amount of products imported and produced domestically with their respective conversion factors are used to calculate the area of export. The formula is given in slide 28 in annex 1.
The areas calculated by consumptions are converted to quantities of five specific ecological categories of lands and sea types including cropland, forest, pasture, built land, and sea according to which land types are required for production or assimilation of these items. For example, if the resource is grain, then the area is reflected as arable or cropland.
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The sum of footprints of all the products consumed within that category is the total Footprint. For example, the Footprint of cropland includes cereals, cotton, processed oils, and fodder crops for livestock.
Footprints are multiplied by equivalence factors to express the final footprint in global hectares. Each land type is assigned an equivalence factor that reflects its relative capacity to produce biomass. The different land types with varying productiveness are dealt by the use of equivalence factors. Hence the regions with varying quantities and composition of areas can be compared.
5.1.2 Energy Footprint
Energy balance is determined by considering both local and direct use of energy and embodied energy in categories of traded goods.
“Embodied Energy is the energy used during a product's entire life cycle in order to manufacture, transport, use and dispose of the product”. The data for the embodied energy are well published and available. The UN's COMTRADE database with trade flows are used to generate estimates of embodied energy. The embodied energy is given in terms of energy intensity (GJ/tonne).
There are mainly two ways of translating the energy consumption to the energy land.
Waste Assimilation / Carbon Sequestration
The direct energy consumption is adjusted for carbon content according to the primary fuel used. “The energy is translated into CO2 emissions using the national fuel mix profile of the producing country for exports, and using the world average fuel mix for imports”. Carbon dioxide (CO2) emissions due to human activities are quantified. These CO2 emissions then are converted into footprint by considering the amount of land required to sequester CO2 emissions. The carbon sequestration method takes into account the assimilative capacity of forests by deducting the emission captured by oceans and assigns the necessary forest area.
The area required is represented by:
Area (ha) = CO2 Emissions (tons) * (1 - fraction absorbed by ocean) / Sequestration Rate (tons/ha)
Based on the above formula, “the sequestration area is calculated by deducting the approximately one-third of anthropogenic emissions absorbed by the oceans from the total anthropogenic emissions (IPCC, 2001)”. This method of carbon sequestration rate to convert into energy land is mostly used method.
Another method for calculation of energy land is biomass substitution. “The biomass substitution approach calculates the area needed to replace fossil fuels with their energy equivalent in fuel wood”.
The area is given by
Area (ha) = Energy (GJ) / [Round wood yield (GJ/ha) * Expansion Factor (-)]
Where; expansion factor accounts for additional biomass used for fuel from limbs, small trees etc.
5.1.3 Hydropower and Nuclear Energy
In ecological footprint, areas occupied by hydroelectric dams and reservoirs are taken into account as built area. “The hydropower Footprint is calculated for each country using the average ratio of power output to inundated reservoir area for a selection of large dams for which both surface area and power output data are available”. Currently, Nuclear Energy is considered same as fossil energy as omission would misinterpret the footprint thereby the ecological performance.
The ecological footprint is summarized in six ecological categories. The footprints for individual consumption categories are aggregated to reach the total ecological footprint of the entity or population. The sum of Crop production, grazing, forestry, fisheries, and built-up areas are mutually exclusive and equals the total Ecological Footprint.
The total is compared to how much bio capacity exists within a country. The whole structure of the footprint calculation is shown in Fig.1. Structure of Footprint and Biocapacity Calculations.
The compound method depends on material flows at the national level and established trade data. National data gathers aggregate resource demand which doesn't require the information of end use. Therefore, compound method is more robust for comparisons between nations. With the same assumption and international data, different countries are compared. The World Wide Fund for nature's (WWF) Living Planet Report (LPR) uses the compound method for Ecological footprint and presents it as one of two main indices to quantify changes in the state of the Earth's ecosystems.
The disadvantage of this method is it doesn't give any disaggregated data, so the sector wise footprint information cannot be derived.
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5.2 Component Based Approach
With the compound method, the consumptions are estimated through analyses of component activity and material flow. Individuals or organizations' consumption is combined in a bottom-up manner to the top required level.
It incorporates basic lifecycle data of relevant components for resource consumption and waste production. Emphasis is given to the activities rather than the cumulative resource use. This approach relies on sources that are more accessible to individuals and organizations. The main sources of data for the component method are raw data collection from the field and life cycle studies.
For some activities, the Ecological Footprint values for certain activities are pre-calculated using data appropriate to that particular entity. The land use categories used for compound analysis are also used for component-based analysis.
The component method involves data collection from range of activities such as transport, energy use, materials and product consumption etc.
The list of components impacts which are typically considered with this approach are:
- Direct Energy
- Material & Waste
- Built land
It considers the effects of the above components or activities and converts these into equivalent land areas in global hectares (gha).
5.2.2 Conversion Factor/ Footprint of Component
“Conversion factors take into account all the activities necessary to the production of a particular resource”. The application of lifecycle analysis to the production of a product is fundamental in component footprint. This allows for a fuller picture of the impacts associated with material production and use as well as distinction between primary and secondary like manufactured products.
The life cycle assessment data are required to derive the ecological conversion footprints for components. The conversion factor needs to take into account the transport, processing and agriculture energy. For material and transport elements, it further makes allowance for the embodied energy, the energy land etc need to be included.
The data for the component are more specific to the particular activity or area, thus data collection demand long time. Additional care has to be taken to avoid double-counting of impacts as component method is concentrated at detailed activity and more vulnerable to double counting.
The conversion factors for certain activities are calculated taking into account related factors like transportation, processing, maintenance etc. Some example of the pre calculated values are given in presentation slide 37 in the annex 1.
Since many people can identify with the activities of component, the component method is simplistic and educative. The activities like production of waste and the consumption of electricity etc are built around people's daily routine, and people can participate and understand them. This method has the benefit of greater local transparency, which facilitates comparisons between impacts of different activities and experimentation with possible sustainability scenarios.
However, the comprehensive component list and reliability of the life-cycle assessment (LCA) and determines the overall accuracy of the final result. Hence, this approach has dangers of producing inaccurate results due to incomplete and inaccurate information.
Colorado College conducted ecological footprint using component based approach. The method for calculation and assumption are given in their report. Another example is Regional Stepwise™ developed by Best foot forward organization based on component approach to find the ecological footprint of a region or community.
Ecological footprint doesn't consider the loss of productivity from soil erosions. It excludes effect of pollution, toxic. “Resource and waste flows that cannot be measured are excluded from the assessment”. Many activities excluded from the ecological footprint is already described in chapter 3.
The accuracy of the conversion factors and footprints itself are constrained by data quality and availability. Proxies are used which may reflect true activity but they are not as reliable as primary data. Thus proxies reduce the reliability of the footprints calculated.
There are some potential errors types of errors such as data errors, assumption errors, systematic misinterpretations etc in the ecological footprint which is important in checking the validity and reliability of the ecological footprint results.
The ecological footprint methodology is undergoing significant development and regularly incorporates new data and scientific knowledge as it becomes available. The Global Footprint Network is continually improving the methodology through the National Footprint Accounts.
Careful planning is required before footprint project in order to determine the best methodology to adopt. The choice of method is determined primarily by scale and data availability and the purpose of foot printing.
Each method has its benefits and uses. Component methods allow detailed footprints but may be unreliable as data quality is questionable. On the other hand Compound footprinting may result in a more robust overall value but the disaggregated subcomponents may be unreliable.
The combination of methods can be used for footprint calculation to explore the possibility of applying the best elements of each method. The component method that is combined with compound Ecological Footprints assessment can overcome the weaknesses of respective methods. Numerous Studies for organizational, municipal and regional are conducted by calibrating component-based estimates on past and present compound national.
Chambers N, Simmons C, Wackernagel M (2000): Sharing Nature's Interest: Ecological Footprints as an indicator of sustainability, Earthscan, London
McLoone A et al (- ): The Ecological Footprint Analysis of SMEs within Mid-West region of Ireland, University of Limerick, Ireland.
Wackernagel M. et al (2007): Current Method for calculating National Ecological Footprint Account, 2007, Science for Environmental and sustainable society, Vol 4. No1, Research Center for Sustainability and Environment Shiga University
Wackernagel M et al (2005): National Footprint and Biocapacity Accounts 2005: The underlying calculation method, Global Footprint Networks
Wright P. E (2002): Ecological Footprint of Colorado College: An Examination of sustainability , Colorado
Ecological Footprint Modeling: http://www.rprogress.org/energyfootprint/eco_footprint/ 15/11/2007
Footprint Methodology: http://www.footprintnetwork.org/gfn_sub.php?content=datamethods 30/10/2007
Stepwise Methodology: http://www.bestfootforward.com/regionalstepwise.html#desc 12/11/2007
Summary of Book Sharing Nature's Interest:
Technical Report on Methodology: http://www.steppingforward.org.uk/tech/index.htm 5/11/2007
WWF, Living Planet Report (2002); http://assets.panda.org/downloads/lpr2002.pdf 23/11/07