Household electrical energy consumption is typically studied in two categories: a) energy consumption for familiar end uses, and b) energy consumption for miscellaneous (other or residual) end use. Assignment of the different electrical energy uses to these two categories is not standardized, with different research groups using different assignments. Familiar end uses generally include space heating, air conditioning, water heating, refrigeration, cooking, clothes drying, dish washing, lighting, television, and furnace fans.