Here are the steps we use to compute an ENERGY STAR Score:
- We calculate your Actual Source EUI by dividing your Source Energy by your Gross Floor Area (GFA).
- We calculate your “Predicted” Source EUI. We start with the average Source EUI for your property type and make adjustments based on your location (for climate and weather data – using HDD and CDD) and your specific Property Use Details (such as Hours of Operation and Number of Workers). For example, if you have less than the average number of workers, we’ll assume you needed a little less energy than average. If you had a very hot summer, we’ll assume you needed a little more energy than average.
- We compare your Predicted Source EUI with your Actual Source EUI. If your actual EUI is lower (better) than your predicted EUI, then you are using less energy than we predicted and your score will be above 50. If your actual EUI is higher (worse) than your predicted EUI, then you are using more energy than predicted and your score will be below 50. The ratio of your actual source EUI to your predicted source EUI is called the efficiency ratio, which can be mapped through a lookup table to determine your 1 -100 ENERGY STAR score.
For more information, see our ENERGY STAR Score Technical Reference.