Environmental Engineering Reference
In-Depth Information
Appendix
A.1 Energy Units and Prefi xes
The legal unit of energy is called a watt second (Ws) or joule (J). The most common
units of energy are normally measured in kilowatt hours (kWh). Table A.1 sum-
marizes the units commonly used in the energy sector. Table A.2 shows the elements
and prefi xes for energy units.
Table A.1
Conversion factors between different units of energy.
kJ
kcal
kWh
kg coal
equivalent
kg oil
equivalent
m
3
natural
gas
1 kilojoule
(1 kJ = 1000 Ws)
1
0.2388
0.000 278 0.000 034
0.000 024
0.000 032
1 kilocalorie (kcal)
4.1868
1
0.001 163 0.000 143
0.0001
0.000 13
1 kilowatt hour (kWh) 3600
860
1
0.123
0.086
0.113
1 kg coal equivalent
29.308
7000
8.14
1
0.7
0.923
1 kg oil equivalent (oe)
41.868
10 000
11.63
1.428
1
1.319
1 m
3
natural gas
31.736
7580
8.816
1.083
0.758
1
