Measuring our impacts

The UN greenhouse gas inventory follows the principles of the Greenhouse Gas Protocol developed by the World Resources Institute and the World Business Council for Sustainable Development and is compatible with ISO 14064. The Greenhouse Gas Protocol has been modified to suit the specific needs of participating UN entities. The results of the latest greenhouse gas inventory can be seen here.


What does the UN Greenhouse Gas inventory cover?


The October 2007 decision of the Chief Executives Board (CEB) limits the boundary of the UN greenhouse gas inventory to emissions from facility operations and travel that can be influenced by management-level decisions. These include emission categories associated with the purchase or generation of electricity and heat (such as steam), use of refrigerants (for air-conditioning and refrigeration) and air, sea and ground transportation.

The inventory includes the six greenhouse gases (GHG) originally covered by the Kyoto Protocol: CO2, CH4, N2O, HFCs, PFCs and SF6. Additionally, the UN also logs the emissions of other GHGs not covered by the Kyoto Protocol, namely hydrochlorofluorocarbons (HCFCs) that are governed by the Montreal Protocol and are reported under the ‘Optional Emissions’ category. GHG emissions are reported separately for each greenhouse gas both in terms of their mass, and as an aggregate using the common comparable unit of carbon dioxide equivalents (CO2eq), using the global warming potential (GWP) of each substance.

The common minimum boundary excludes several sources of greenhouse gas emissions that could result from UN activities. Recommended best practice is to voluntarily document all sources of emissions not included in the minimum boundary under an additional category called Optional Emissions. These include:

  • Emissions associated with decisions for which individual staff members are responsible and that relate to their personal sphere (e.g. emissions from personnel commuting to and from the work place),
  • Emissions from projects implemented by external entities,
  • Emissions due to couriers and postal mail,
  • Embodied carbon in products and equipment used by the UN, for instance food, beverages, paper and computers,
  • Emissions from the decomposition of organic waste and from waste water treatment arising from UN premises.
  • Emissions of climate relevant gases not within the common minimum boundary, i.e. HCFCs

How are emissions calculated?


Estimation and reporting of the emissions is done through the following tools:

  1. Formatted files for data collection, available in English, French and Spanish;
  2. A stand-alone air travel emissions calculator;
  3. An online emissions calculator for the remaining sources and
  4. A web-portal, where the data files can be uploaded to generate emission results.

The substantive inputs for developing the system were provided by the Sustainable United Nations (SUN) team, and software development was led by DFS. The air travel emissions calculator is a proprietary product of ICAO.


How is the reporting process evolving?


Over the past years improvements have been made to the data collection systems, for example:

  • A number of proxy methodologies were updated for reporting type and number of staff, and for several emission sources when the activity data was not available. The data collection files were updated with more concise guidance and tested extensively to avoid delays in emission calculations.
  • ICAO regularly updates the air travel emissions calculator with the latest industry data and statistics.

The changes made to data collection and reporting tools as well as the development and updating of proxy methodologies have made data reporting easier. It is expected that this will facilitate a larger coverage of offices and facilities in the future. The number of participating entities has grown over time and new organisations and Focal Points have joined the project. Future efforts will focus on replacing or upgrading the existing reporting system wiht a more versatile system and improving the reporting depth (i.e. inclusion of additional offices) among participating organisations and data quality.

Responding to the magnitude and significance of emissions from air travel and transportation used for official travel, a decision was taken by the EMG to make reporting mandatory, despite this being optional under the Greenhouse Gas Protocol. In accordance with international guidance of the protocol, emissions from the combustion of biomass or bio-fuels in equipment and vehicles are reported as an information item only. Similar guidance exists for Ozone Depleting Substances controlled by the Montreal Protocol such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), which are mostly used as refrigerants. However, due to their significant presence in UN facilities they have been included under the Optional Emissions category. It has also been decided to make the reporting of CFCs and HCFCs mandatory in the future. While recognising the significance of non-CO2 effects of aviation no provision was made for their estimation or incorporation - pending more clarity and internationally accepted guidance on this issue.


What are the issues with data quality?


Aspects of the methodologies used initially have been simplified over time in recognition of internal capacity and resource limitations. It is accepted that in some circumstances this affects the accuracy of the inventory. Such changes were made in Refrigerants, Purchased Steam and Vehicles (mobile sources). Where data was not readily available, estimates were based on clearly defined assumptions and proxies. A review of the methodologies, data and process is undertaken annually and the IMG is actively involved in this process. More rigorous methods and procedures will be introduced, based on feedback, as resources allow.

A few agencies have prepared Inventory Management Plans (IMPs) and others are expected to follow suit. An IMP is an internal document that records the details of each inventory and helps to institutionalize the process for preparing a high quality inventory. Efforts will also be made to develop a quality assurance and control (QA&QC) programme for the inventory, including external verification.


Why is it difficult to compare emissions between years and organizations?


The use of a common methodology and the development of proxy methodologies for issues identified as major data gaps have helped to improve the comparability of the inventory across agencies and between years. However, detailed analysis is needed to interpret the trends. The difference in the size, nature and operations of agencies, changes in coverage of offices across years, changes in methodologies, scope and underlying databases of the emissions calculator means that comparisons cannot be accurately made unless detailed analysis is done.

Read about the UN GHG inventory boundaries

Find out how the UN is reducing its impacts.