Emissions boundaries

One of the first (and more critical and challenging) steps in the development of a GHG emission inventory is the definition of the boundaries of the inventory. These boundaries refer to the coverage and extent that will be taken into account for the inventory process, they determine what is included and what is not. Organizational boundaries define the operations, facilities, and sources that are to be included in the inventory, while Operational boundaries categorize the emissions resulting either directly or indirectly from the organization’s operations, facilities, and sources.

The UN system has an agreed common minimum boundary for its greenhouse gas inventory, which specifies activities, emission sources and greenhouse gases (GHG), as described below.

The October 2007 decision of the UN system Chief Executives Board (CEB) limits the boundary of the UN to facility operations and travel. The UN agencies, funds and programmes therefore account for greenhouse gas emissions from headquarters, regional and administrative centres and field offices. Emissions from activities that are funded both through the regular and extra-budgetary sources are included in the UN’s boundary.

Among others, the following are not included in the UN minimum agreed boundary:

  • Emissions from staff commuting to work;
  • Emissions from projects implemented by external entities or from grants to other institutions;
  • Emissions from electricity losses, courier, mail, printing and shipping;
  • Embodied carbon in for instance food, beverages, paper and computers; 
  • Emissions from construction;
  • Emissions from the decomposition of organic waste and from waste water treatment arising from UN premises; and
  • Emissions of climate relevant gases not within the common minimum boundary, ie. HCFCs

Emission sources


The greenhouse gas inventory of UN system organizations includes, as a minimum, the following emission sources:

  • Emissions from transport such as official air, rail or road travel
  • Use of energy either through burning fuel to generate on site electricity, steam and hot water and that used for cooking, or energy purchased from utilities or other sources such as electricty, steam or hot water.
  • Fugitive emissions, such as leakage of greenhouse gases from refrigeration and air-conditioning equipment

If for some reason a UN organization is not able to include the above in their greenhouse gas inventory, the omission is documented and an explanation provided in the Inventory Management Plan.


Greenhouse gas coverage


The greenhouse gas Protocol requires reporting of the six greenhouse gases originally covered by the Kyoto Protocol, namely CO2, CH4, N2O, HFCs, PFCs and SF6. There are no emissions of SF6 resulting from UN activities. The methodology requires emissions to be reported separately for each greenhouse gas as well as aggregated as carbon-dioxide equivalent (CO2eq).

To assess inventory completeness, organizations are asked to identify and report the data gaps in coverage of emissions under the minimum agreed boundary. Whenever data is not readily available, organizations have the option of estimating greenhouse gas emissions based on clearly defined assumptions and proxies (for example kWh per square metre of office floor space), which are discussed in the individual agencies inventory management plans. The UN’s methodology also allows the use of proxies to estimate greenhouse gas emissions from 'small' offices, defined as offices with fewer than five staff members. If such offices are excluded altogether from the inventory, the data gap should be reported with an indication of plans on how to account for these small offices in the future.


Emissions from sources outside the UN minimum agreed boundary


UN system organizations are allowed the flexibility to report on an optional basis on emissions from sources that lie outside the UN minimum agreed boundary. These could include, for example, emissions from commuting, waste and paper use. If organizations choose to do so, emissions from these source categories should also be reported in subsequent years for the purpose of time series comparison.

See the results of the latest inventory