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A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a non-SI unit of energy equal to 3.6 megajoules (MJ) in SI units, which is the energy delivered by one kilowatt of power for one hour. Kilowatt-hours are a common billing unit for electrical energy supplied by electric utilities.
The SI unit is watt (W). Another unit common in non-metric regions or sectors is the ton of refrigeration, which describes the amount of water at freezing temperature that can be frozen in 24 hours, equivalent to 3.5 kW or 12,000 BTU/h. [1] [2] [3]
As total energy consumption is in kilowatt hours and heating degree days are [no. days×degrees] we must convert watts per kelvin into kilowatt hours per degree per day by dividing by 1000 (to convert watts to kilowatts), and multiplying by 24 hours in a day (1 kW = 1 kW⋅h/h). Since a 1 °C temperature change and a 1 K change in absolute ...
A unit of electrical energy, particularly for utility bills, is the kilowatt-hour (kWh); [3] one kilowatt-hour is equivalent to 3.6 megajoules. Electricity usage is often given in units of kilowatt-hours per year or other periods. [4] This is a measurement of average power consumption, meaning the average rate at which energy is transferred ...
Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced each hour.
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property.
Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10 −6 metre).
It was originally defined as the rate of heat transfer that results in the freezing or melting of 1 short ton (2,000 lb; 907 kg) of pure ice at 0 °C (32 °F) in 24 hours. [1] [2] The modern definition is exactly 12,000 Btu IT /h (3.516853 kW). Air-conditioning and refrigeration equipment capacity in the U.S. is often specified in "tons" (of ...