How to Normalize Utility Bills for Weather
Weather normalization removes the effect of a hot summer or cold winter so you can compare energy use across years and buildings.
Comparing raw utility bills from one year to the next can be misleading. A cold winter or a hot summer can make a building look worse than it really is.
Weather normalization uses heating and cooling degree days to remove those effects. The most common approach is change-point regression: fitting a linear relationship between monthly energy use and monthly degree days.
A 3-parameter model captures heating or cooling only. A 5-parameter model captures both. The result is a weather-normalized annual consumption that can be compared across years, buildings, and climate zones.
This normalized baseline is the foundation of ASHRAE 211 Level 2 and 3 savings calculations.