Under the Energy Policy and Conservation Act of 1975, the National Bureau of Standards (NBS) conducted household appliance efficiency testing to assist the Department of Energy (DOE). The Act mandated that the DOE should develop testing procedures to measure the energy efficiency and set energy efficiency targets for household appliances. The Act also stipulated that the DOE monitor efforts by manufacturers to improve efficiency. The testing efforts by NBS are responsible for the numbers on yellow stickers that enable consumers to compare different appliances.
To see more photos like the one below, visit the Appliance Efficiency Photo Collection in the NIST Digital Archives.