Energy Management Bureau  

    GLOSSARY

Power - The capacity of a device to convert energy from one form to another, sometimes measured in kilowatts (kW) or its multiples. Energy appliances and devices are usually given a 'rated capacity' (in kW, MW, GW etc) reflecting the rate at which they can convert energy from one form to another.

Watt - The international unit of power, named after James Watt. Power is the rate of doing work, and work is measured in joules. A Joule per second is a watt.

KW   (KILOWATT) - A unit of electric power equal to 1,000 watts, or to energy consumption at the rate of 1,000 joules per second.

Energy - A measure of the amount of 'work' that can be done by, or is needed to operate, an energy conversion system. It is the power of the device (in kilowatts) multiplied by the time it is in use (hours).

KWh (KILOWATT HOUR) - A measure of energy consumption. equivalent to the use of 1,000 watts of power over one hour. A 100-watt light bulb used for 10 hours would consume 1kWh of electricity.

DEGREE DAYS - Degree days are used to compare building energy usage with the outside air temperature. Heating degree days are the number of degrees by which the mean outside air temperature (over 24 hours) on each day are less than a given base temperature of 15.5C.