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• Annual CO2 emissions from onsite combustion are fixed over time and equal the sum of the amount of each type of fuel used times its carbon coefficient as provided by the U.S. Environmental Protection Agency.

  • The CO2 emissions from electricity are based on the project’s local grid and will show a decline over time.

  • Emissions are calculated by multiplying the amount of electricity used by the carbon coefficient of its current grid based on the most recently available data. For the U.S., the carbon coefficient is the regional eGRID factor published by the EPA. For Canada, there are the published carbon coefficients per province. For projects elsewhere, the carbon coefficient is from national grid data.

  • The carbon coefficient of each grid is calculated to decline by 95% over 25 years in a linear fashion. While this is not strictly true of any specific grid, it is directionally true of electric grids globally, which are rapidly decarbonizing because it has become less expensive to develop new renewable power plants than new fuel-fired plants.

  • The BAU carbon projection includes a trendline showing a straight-line reduction to zero over 25 years for reference purposes.

This USGBC operational carbon projection is not based on predictions for specific grids but on the general prediction that grids will substantially decarbonize over the next quarter century, continuing the trends of the last 15 or 20 years. High-level takeaways from this exercise are:

• The project’s carbon emissions from electricity will diminish dramatically over 25 years.

• The project’s carbon emissions from onsite combustion will remain.

• The project’s carbon emissions from electricity are non-zero now and will continue to be significant over the next 10 to 15 years, except for a few very clean grids.

Develop a high-level estimated end-use breakdown Determine the end-use breakdown for all applicable end-uses in the building, including energy type (electric, fuel), the total percentage of the building’s energy consumed by each end-use, and the total percentage of site energy associated with the end-use. When developing these estimates, only a high-level analysis is required. The exercise aims to educate project teams about the end-uses that are driving most of the onsite fuel and electrical use to help project teams better understand what is driving carbon emissions; it is not meant to be used for more detailed processes.

Developing an end-use estimate is a standard engineering exercise in an energy audit. Listed below are ways end-use breakdowns are created, depending on the granularity of the available data and the level of technical resources available to the team.

U.S. Green Building Council LEED v5 Reference Guide for Operations and Maintenance, April 2025 Launch Edition 105