Global Common Carbon Metric Project by the Low Carbon Building Group


Professor Gupta is an expert advisor to the UNEP: Sustainable Building and Climate Initiative on the Global Common Carbon Metric project. The Common Carbon Metric is the calculation used to define measurement, reporting and verification for GHG emissions associated with the operation of buildings and particular climate regions. It does not include value-based interpretation of the measurements such as weightings or benchmarking.


The Common Carbon Metric project, being led by the World Green Building Council in partnership with the UNEP Sustainable Buildings & Climate Initiative and the Sustainable Building Alliance has three specific goals:

  • Benchmarking: to provide a consistent reporting framework for both industry and government that work in a local and international context;
  • Baselining: to support consistent reporting of operational carbon footprints from buildings and enable comparisons of buildings across cities and countries, and provide a basis for funding allocations and international agreements;
  • Monetising: to provide a consistent measurement basis for monetisation of carbon trading measures for the building sector, which will in turn stimulate market activity by incentivising energy efficiency.


While all stages of a building's life-cycle (including construction and demolition) produce carbon emissions, the building's operational phase accounts for 80-90% of emissions resulting from energy use mainly for heating, cooling, ventilation, lighting and appliances. Therefore, this is the stage of the building's life-cycle that is the focus of the Common Carbon Metric.

Working in close cooperation, environmental building ratings organisations, local, regional, and national governments, research institutions, industry experts, and private sector stakeholders have developed a common measurement for GHG emissions from building operations that takes two complementary approaches; one assesses performance at the building level (bottom-up), and the other at the regional or national level (top-down).

The actual reporting is done in weight of carbon dioxide equivalent (kgCO2e) emitted per square meter per year = kgCO2e/m2/year (by building type and by climate region). The basic outline methodology is as follows:

  • Define the boundary of the premises (building);
  • Collect annual energy use data by fuel;
  • Identify the building type and floor area;
  • Multiply each fuel use by the appropriate emission factor;
  • Calculate performance indicators: kWh/m2 per annum, kgCO2e/m2 per annum;
  • Adjust if necessary, e.g. for weather and/or occupancy;
  • Review against appropriate reference data;
  • Establish energy and CO2 reduction targets;


This globally harmonized method for measurement, reporting, and verification of energy use and green house gas emissions provides the basis for establishing baselines, performance benchmarking, and monitoring building performance improvements. These activities are in turn fundamental to inform international mechanisms for carbon trading, policy development and analysis, and progress reporting on the mitigation of GHG emissions from buildings. Policy- and decision makers can produce reports from the data collected through these METRICs for jurisdictions, regions, large building stock owners, cities or at a national level to form baselines that can be used to set targets and show improvements in carbon mitigation in the building sector.



Research Reports

  • Phase II - Preliminary findings report
    Dated: January, 2012
  • Phase II - Final report
    Dated: June, 2012

Related book chapters

  • Gupta, R. and Chandiwala, S. (2010). A critical and comparative evaluation of CO2 emissions from national building stocks of developed and rapidly-developing countries - case studies of UK, USA, and India. Cities and Climate Change: Responding to an urgent agenda. The World Bank, Washington, USA.
  • Gupta, R. and Roaf, S. (2008). Counting carbon from buildings and cities: models and methodologies. In: Roaf, S and Bairstow, A. eds. The Oxford Conference: a re-evaluation of education in architecture. WIT Press. pp 83-86. ISBN 978-1-84564-206-8


Conference Presentation

  • UNEP: SBCI's Common Carbon Metric
    UNEP: SBCI Symposium on Sustainable Buildings, Philadelphia, USA, 27-28 October 2011
  • A Common Language for CO2 performance of Buildings
    Buildings Under UNFCCC Flexible Mechanisms, 14th March 2011, Bonn, Germany


Low Carbon Building Group

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