Carbon Emissions from Building Energy Use

Portfolio Manager is an online tool that helps buildings take control of their energy to increase energy efficiency and help protect our environment. Organizations have used Portfolio Manager to benchmark the energy performance for billions of square feet of office buildings, schools, hotels, and other buildings across the country and thousands of buildings and plants have earned the ENERGY STAR for superior energy efficiency.

Portfolio Manager can now help businesses see how their buildings’ carbon emissions compare to others in the same region and across the country as well as measure their progress in reducing emissions, thanks to the recent addition of carbon emissions factors from EPA’s Emissions & Generation Resource Integrated Database (eGRID). These emissions factors are consistent with those used by major greenhouse gas reporting protocols, including the World Resources Institute/World Business Council for Sustainable Development Greenhouse Gas Protocol. This consistency makes it easier for organizations to quantify their carbon inventories and provides a transparent corporate accounting, inventory, and reporting method.

The table below illustrates that an ENERGY STAR qualified building in each of the 26 eGRID subregions emits at least 26% less carbon than a typical office building. It also shows the carbon emissions rate for a building that meets the Architecture 2030 Challenge goal of 50% below average.

For electricity, the emissions factors come from EPA’s Emissions & Generation Resource Integrated Database (eGRID), generated from utility data for each of the 26 subregions of the U.S. power grid. Based on the zip code of each building entered, Portfolio Manager identifies the appropriate subregion and emissions factor, and provides a graphic comparison of the subregion’s emissions rate and electric generation fuel mix to the national rate³. Shortly, Portfolio Manager will also provide the ability to compare individual buildings to the regional and national CO2 emissions rates. Below is a map of the 26 eGRID subregions identified by their official eGRID name as well as an added geographic label to help users interpret the names of the eGRID subregions (e.g. RFCE = MidAtlantic).

As the table and map illustrate, emissions rates vary significantly across the country. The differences reflect the use of different fuels to produce electricity. For example, electricity produced from hydropower in the Northwest results in fewer CO2 emissions than electricity produced from coal in the Midwest. Therefore, buildings with the same energy consumption can have substantially different emissions profiles. Nevertheless, buildings across the country have opportunities for improvement in their energy efficiency and thereby reduce their carbon emissions. In fact, energy efficiency improvements in those buildings located in regions with higher emissions rates can have a greater impact on CO2 emissions than those in regions with lower emissions rates.

For example: Total annual energy use for a typical 200,000 square foot office building in Colorado would generate twice the amount of CO2 emissions as the same building in Oregon — 8 million pounds versus 4 million pounds. If, however, the efficiency of each building was improved to the level of the average ENERGY STAR building, the avoided CO2 emissions would be 2.1 million pounds in Colorado and 1.1 million pounds in Oregon.

For more information, see Portfolio Manager and eGRID.