Refrigerators can have very different energy consumption
depending on the year of manufacture and features that affect energy use such
as size, automatic defrost, or side-by-side design. To estimate the energy
consumption of these appliances, we use the calculation method described in the
Equation 8 where EC = Annual energy consumption (kWh/year) AV = Adjusted volume (cubic feet) EF = Energy Factor (cubic feet•day/kWh) The refrigerator / freezer adjusted volume is intended to capture in a single parameter the relatively high energy intensity of the refrigerator's frozen food compartment compared to the fresh food compartment. Equation 9 is used to calculate adjusted volume (US DOE 1995), and corresponds to the definition used in specification of federal minimum efficiency standards.
Equation 9 where AV = Adjusted volume (cubic feet) size = "Nominal" refrigerator/freezer volume (cubic feet) frac = Fraction of refrigerator volume devoted to fresh-food storage (0 ≤ frac ≤ 1) For side-by-side refrigerators, a fresh-food fraction of 0.6 is used, while all other configurations use a fraction of 0.66. Note that this model does not account for refrigerator usage factors that might vary among units, such as refrigerator and freezer temperature settings, door opening frequency, food loading rates, and ambient temperatures. While these factors can have a large impact on energy consumption, their effect has not been quantified in a way that could be incorporated into a parametric model such as this. |