Reading refrigerator ratings: kWh, adjusted volume and the standard
An ENERGY STAR refrigerator listing has several numbers. Some are useful for cost, some are easy to misread. Here is what each one means, using the definitions in the official dataset.
Annual energy use (kWh per year)
This is ENERGY STAR's estimated annual energy use under typical conditions, calculated according to U.S. Department of Energy test procedures. It is the number to use for cost: multiply it by your price per kWh. Your actual use will vary with how often the door is opened, the room temperature and how full the refrigerator is kept.
Total volume and adjusted volume (cubic feet)
Total volume is the interior volume of the refrigerator and freezer compartments together.
Adjusted volume weights the freezer compartment more heavily, because freezers need more energy per cubic foot than the fresh-food compartment. It is the sum of the fresh-food volume, any cooler compartment volume, and the freezer volume multiplied by an adjustment factor. The federal energy standards are written in terms of adjusted volume, so it is the fairest way to compare sizes across types. Two models can have the same total volume and different adjusted volume if one has a bigger freezer.
The federal standard and the percentage below it
The U.S. Department of Energy sets a maximum annual energy use for each configuration and size of refrigerator. ENERGY STAR certified models must generally beat that standard by at least 10%. The dataset lists how far each model is below it. A higher percentage means more savings compared with the minimum allowed.
A note on how we show it. The percentage is published by ENERGY STAR, and we display it as published and do not recalculate it. We also checked it against the two published kWh numbers. For 1,111 of 4,885 listings, the percentage differed by more than one point from what you get by dividing the annual energy by the published standard, by up to about 6 points. Bottom-freezer and side-by-side models were the clearest case. We do not know the exact reason, so on model pages we show the published percentage and leave out the standard's kWh figure, to avoid putting two numbers side by side that do not reconcile. A handful of listings carry a negative percentage. We do not display those.
Product class and type
Each listing has a product class that describes defrost type, freezer position, ice maker and other features that affect the standard it is measured against. The type (top freezer, bottom freezer, side-by-side, freezerless, compact) is the simplest grouping. Compact means under 7.75 cubic feet of total volume and 36 inches or less in height.
How to compare two models
- Compare the same type. A top freezer and a side-by-side are different products.
- Compare similar adjusted volume. A larger refrigerator will use more energy simply because it is bigger.
- Among those, a lower annual kWh is better. Features such as an ice maker or a through-the-door dispenser change both the product class and the energy use, so compare those features too.
- Use your own electricity rate to turn the kWh into dollars.
The comparison tool lists the rows where models differ and names the model with the lowest listed annual energy use, saying when the models are not alike in type or size. For typical numbers, see how much electricity a refrigerator uses.