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 100watt 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 15.5°C.
