To help cities and states implement BPS (Building Performance Standards) policies, the DOE Data Tools portfolio has added carbon and other GHG (Greenhouse gas) emissions metrics to their tools. The information outlined here outlines the methodology used to implement these metrics in the Audit Template and Asset Score.
Carbon Metrics in Audit Template
GHG emissions are calculated for many metrics across Audit Template. Emissions are calculated by multiplying energy consumption by fuel type specific emission factors.
CO2e emissions factors for fuels burned on site. Source: ENERGY STAR technical reference
Non-electric energy sources have no variability with time or location, however electric factors have regional fuel mix considerations. For electricity, a building's zip code gets mapped to eGRID regions. Each eGRID region has their own fuel mix and set of emission factors to calculate GHG emissions for electric consumption.
GHG Metrics in Audit Template Tool Input Screens
Metered and Delivered Energy – Monthly energy use for each fuel type is expressed in kg of Co2 emissions/day
Annual Energy Summary – Calculated using the monthly metered and delivered energy consumption, the Annual Summary provides the annual energy by fuel type, expressed in kBtu and CO2 emissions
Energy Use by End Use – Energy use by end use for each fuel type is expressed in tons of Co2 emissions
Energy Savings Opportunities – Energy use by Energy Efficiency Measure and Packages are expressed in tons of Co2 emissions
Existing Building EUI/ECI – Annual carbon emission intensity for the whole building and site and displayed as kg CO2e/ft2/yr
Carbon Metrics in Asset Score
Metrics in Asset Score include calculations of total building GHG emissions before and after retrofit, GHG emissions by end use (e.g., lighting, heating, cooling) before and after retrofit, and GHG emissions by fuel type (e.g., natural gas, electricity) before and after retrofit. These calculations are displayed visually as kg CO2e/ft2/yr in the following sections of asset score reports:
- Annual carbon emission intensity values for the whole building
- Carbon emissions by end use chart
- Carbon emissions by fuel type chart