Carbon Footprint

Primary Source: Jeswani, H. and Azapagic, A. (2006) Carbon Footprint Modelling in Report on the SWOT analysis of concepts, methods, and models potentially supporting LCA. Eds. Schepelmann, Ritthoff & Santman (Wuppertal Institute for Climate and Energy) & Jeswani and Azapagic (University of Manchester), pp 166-169

Level of analysis: Micro (on substances, products, companies, person, household), meso (sectors) and Macro (on countries and regions)

Assessed aspects of sustainability: Environmental

Main purpose of the assessment:

To estimate greenhouse gases of activities, events, products, services, etc.

Detailed Description

The concept of carbon footprint is being widely used in the public debate on responsibility and mitigation against the threat of climate change.

Carbon footprint represents net emissions of CO2 and other greenhouse gases over the full life cycle of a product, process, service or organisation (Carbon Trust, 2007a). Normally, it is expressed as a CO2 equivalent (usually in kilograms or tonnes per functional unit) and as such is equivalent to the usual LCA impact category Global Warming Potential (GWP). The life cycle concept of the carbon footprint means all direct (on-site, internal) and indirect emissions (off-site, external, embodied, upstream and downstream) need to be taken into account.

Carbon footprint can be calculated using the Life Cycle Assessment (LCA) methodology (ISO 14044). The LCA approach ensures that the emissions from the whole supply chain are accounted for (Carbon Trust, 2006). PAS 2050 is a new British standard for calculating carbon footprints of goods and services, being developed by British Standards Institution (BSI). It is partly based on ISO 14044 and as such does not represent a completely new methodology (BSI, 2008).

The task of calculating carbon footprints with LCA can be approached methodologically from two different directions: bottom-up, based on Process Analysis (PA) or top-down, based on Environmental Input-Output (EIO) analysis (Wiedmann and Minx, 2007). The method of choice will often depend on the purpose of the study and the availability of data and resources. For instance, EIO analysis is suitable for estimating carbon footprints at the macro (national) and meso (industrial sector) levels, including background systems in an LCA. However, for micro-level analysis of processes, products or services, the EIO is not useful and the PA approach is much more appropriate.


The carbon footprint is a sub-set of the data covered by a more complete Life Cycle Assessment (LCA). It focuses on one LCA impact only – climate change.

Since it only focuses on climate change, the data requirements are limited to sources of GHG emissions only.

The number of calculations needed are limited as compared to a full LCA, particularly for systems where energy is the major source of greenhouse gases.

Since it has only one indicator – global warming potential – it is easier to communicate to stakeholders. In theory, provided that the same methodology is used, this should also make it easier for consumers to compare different products based on their carbon footprint.


It is a weakness to only study one environmental impact. It may lead to decisions being optimised after GWP, but resulting in larger impacts on biodiversity, abiotic depletion, toxicity etc.

Estimating a full footprint covering all types of emissions can be quite a complex task.

There is currently a lack of consistency in methods for calculation and reporting, which means it can be difficult to compare published footprints.

Tools currently available for estimation of carbon footprints are either too simple or simplistic or too complex. In particular, the online calculators to estimate an individual’s carbon footprint lack consistency (Padgett, et al., 2008). In addition, most calculators lack information about their methods and estimates, which impedes validation.

Estimating a full carbon footprint covering all types of emissions can be quite a complex task.

The issue of biogenic CO2 flows is not penetrated in ISO standards or in the PAS 2050 BSI standard. The CEPI (Confederation of European Paper Industri) deals with biogenic flows, but in a rather generalised way, and other sectors have not been involved.

Opportunities for broadening and deepening LCA

Since carbon footprint is a subset of a more complete Life Cycle Assessment (LCA), it provides opportunity to use specific data for a relatively simplified analysis.

It is an increasingly popular concept for labelling, marketing, finance and regulation.

In 2007, the Carbon Trust UK launched a ‘carbon-reduction label’ after it conducted pilot ‘footprint projects’ with potato chips, shampoos and soft drinks (UK Carbon Trust, 2007b). Similar initiatives are also underway in other countries (Johnson, 2008).

In a policy context, the carbon footprint can be seen as a subset of the growing demand for life cycle based information that is being used for knowledge-based decision making for sustainable consumption and production policies.

With climate change high up on the political and corporate agenda, carbon footprint calculations are in strong demand.

Quantification of todays performance as well as future possible reduction strategies is a key to prevent climate change; for example, by enhancing energy efficiency and mitigating carbon emissions by using ‘green’ energy, with a final goal to becoming carbon neutral. Calculating a carbon footprint is only the beginning of carbon management, i.e. taking actions to reduce emissions and improve efficiency. Carbon footprinting can be a useful exercise as part of a complete environmental management system.

The EPD concept is an opportunity, presenting only the GHG emissions as a “climate declaration” profile, but at the same time having all the other environmental impacts calculated and documented and certified as well. The concept builds on a sector accepted methodology within the different industrial sectors, so called PCR (Product Category Rules; IEC, 2008), on the ISO 14025 standard on environmental declarations (ISO, 2006), and on the LCA standard. The Carbon Footprint, or climate declarations, are transparent in methodology, and may also be communicated in a simple way on the product packaging. The declarations are comparable for business, but also for consumers.

Threats for broadening and deepening LCA

Although building upon a life cycle approach, carbon footprints address only one environmental impact – global warming potential. If the use of carbon footprint for decision making results in burden-shifting rather than improvements, this could undermine the credibility of the approach.

The current focus on sustainable production and consumption restricts the application of carbon footprints, which are not adequate for assessing and achieving sustainable production and consumption. This requires consideration and evaluation of all relevant environmental impacts simultaneously, and can only be ensured by a complete Life Cycle Assessment.

Environmental labels Type I is an important competitor to carbon footprints. With their digital approach (on-off), they are perhaps viewed as easier to communicate to consumers.

Literature/Internet links

BSI (2008) PAS 2050 Specification for the assessment of the life cycle greenhouse gas emissions of goods and services – under consultation.

Carbon Trust (2006) Carbon footprints in the supply chain: the next step for business. Report Number CTC616, The Carbon Trust, London, UK, available at

Carbon Trust (2007a) Carbon footprinting – An introduction for organisations, available at

Carbon Trust (2007b) Carbon Trust Labelling Scheme, available at

European Commission (2007) ‘Carbon footprint – what is it and how to measure it’ available at

IEC (2008) General Programme Instructions for Environmental Product Declarations, EPD. The International EPD Cooperation. url:

ISO (2006) Environmental labels and declarations — Type III environmental declarations — Principles and procedures. ISO 14025:2006

Johnson, E. (2008) Disagreement over carbon footprints: A comparison of electric and LPG forklifts, Energy Policy, 36(4): 1569-1573.

Wiedmann, T. and Minx, J. (2007) A Definition of ‘Carbon Footprint’, ISA UK Research

Report 07-01, available at



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