Energy Measurement

Although energy can exist in many different forms, it can be measured and compared along a single axis because it can be converted between forms. Measurement of the familiar forms of energy involves measuring quantities of mechanical force, weight, distance, temperature, electric charge and current, and/or time.

	unit	defnition	equivalent units
			joules	kWh	BTUs
SI* unit of energy	joule	Force of 1 newton over distance of 1 meter; Watt second	1	2.777*10-7	9.481*10-4
Commonly unit of electrical energy	kWh (kilowatt hour)	Power of 1,000 watts for 1 hour	3,600,000	1	3,413
Common English units of thermal energy or fuel equivalents	BTU (British Thermal Unit)	Temperature increase of 1 degree Fahrenheit in 1 pound of water at 1 atmosphere	1,055	2.931*10-4	1
	therm	100,000 BTUs	1.055*108	29.3	100,000
	CCF (Hundred Cubic Feet)	1 hundred cubic feet of natural gas at standard pressure			103,100
	GGE (Gasoline Gallon Equivalent)	Energy content of 1 liquid gallon of gasoline	1.2*108	33.4	114,113
Other units of energy	erg	Force of 1 dyne over distance of 1 centimeter	10-7
	(kilogram) calorie	Temperature increase of 1 degree Celseus in 1 kilogram of water at 1 atmosphere	4.19

* The International System of Units (SI) is the modern form of the metric system and has units of measurement defined in terms of seven base units and numerous derived units. Accordingly, the Joule is a derived unit defined in terms of the base units of force (newton) and distance (meter).