How to use the building energy use intensity calculator
Energy use intensity is a year of building energy divided by gross floor area, which puts buildings of different sizes on the same scale. Every fuel is converted to the same unit first: 1 kWh is 3.412 kBtu, one therm of natural gas is 100 kBtu, and 1 MMBtu of purchased steam or hot water is 1,000 kBtu. Adding them and dividing by area gives site EUI in kBtu/ft² per year.
Worked check: a 50,000 ft² building using 600,000 kWh of electricity and 8,000 therms of gas consumes 2,847,200 kBtu, so its site EUI is 56.9 kBtu/ft²·yr. Against the office median of 52.9 that is 107.6%, which lands just above the middle of the pack.
The property-type values in the list are national median site EUI figures of the kind ENERGY STAR publishes from the CBECS survey for use in Portfolio Manager, and they are starting points rather than targets. Operating hours, vacancy and climate move the number a long way within one property type, so pull the current figure for your own property type and enter it in the custom field when the result matters. Note also that this is site energy; a source energy comparison applies a site-to-source factor to electricity and will read differently.
Frequently asked questions
Site energy conversions are fixed: 1 kWh of electricity is 3.412 kBtu, one therm of natural gas is 100 kBtu, and 1 MMBtu of purchased steam or hot water is 1,000 kBtu. Add them all up and divide by gross floor area to get site EUI in kBtu per square foot per year.
Usually it is a good sign, but not always. High vacancy or short operating hours pull usage down on their own, while a 24-hour schedule, a data closet or a commercial kitchen can raise EUI without any inefficiency. Comparisons only mean something between buildings of the same type and similar operating profile.