Glossary · Energy, bills & ratings

Kilowatt-hour (kWh)

Also called: kilowatt-hours · MWh · megawatt-hour

The unit on your electricity bill: one kilowatt-hour is 1,000 watts used for one hour, such as a 100-watt bulb left on for 10 hours.

What it means

A kilowatt (kW) is a rate of power, while a kilowatt-hour is energy used over time. Your meter counts kWh and the bill multiplies them by the price per kWh, which may vary by time of day (see time-of-use pricing). Comparing kWh with gas use in therms, cubic meters or gigajoules requires a conversion.

Why it matters in an audit

Twelve months of kWh readings show your baseload and how much electricity goes to heating or cooling, which helps the auditor estimate savings.

Typical numbers

Reference values with their sources. Your auditor’s report gives the figure for your own house.

What	Value	Source
Conversions	1 kWh = 3.6 MJ (NIST) = 3,412 BTU (EIA)	nist.gov ↗
To gas units	1 GJ ≈ 277.8 kWh; 1 therm ≈ 29.3 kWh	Arithmetic from NIST and EIA factors

Sources

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Related terms

Baseload The energy a home uses no matter the season — fridge, lights, electronics, water heating and standby power — apart from heating and cooling.
Therm The unit many US gas bills use: one therm is 100,000 BTU of heat energy, roughly the energy in 100 cubic feet of natural gas.
BTU and BTU/h A unit of heat energy; BTU per hour (BTU/h) measures how fast a furnace, heat pump or air conditioner delivers heating or cooling.
Time-of-use (TOU) pricing Electricity prices that change with the time of day, usually cheapest overnight and highest when demand peaks.
Kilowatt (kW) A rate of using or producing energy equal to 1,000 watts; running 1 kW for an hour uses 1 kilowatt-hour (kWh), the unit on your electricity bill.

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