Appendices
Appendix 5.1: Energy units and conversion factors
Basic SI units
| Length | metre (m) |
| Mass | gram (g) |
| Time | second (s) |
| Temperature | Kelvin (K) |
Commonly used temperature units:
Celsius (C), Fahrenheit (F)
0°C = 273.15 K = 32°F
1°F = -17.22 °C
1°C = 274.15 K
Fahrenheit temperature = 1.8 (Celsius temperature) +32
Note: Using the term "centigrade" instead of "Celsius" is incorrect and was abandoned in 1948 so as not to confuse it with a centennial arc degree used in topography.
| Multiples | Fractions | ||
| 101 | déca (da) | 10-1 | déci (d) |
| 102 | hecto (h) | 10-2 | centi (c) |
| 103 | kilo (k) | 10-3 | milli (m) |
| 106 | méga (M) | 10-6 | micro (µ) |
| 109 | giga (G) | 10-9 | nano (n) |
| 1012 | téra (T) | ||
| 1015 | péta (P) | ||
Derived SI units
| Volume : | hectolitre (hL) | 100 L |
| cubic metre (m3) | 1000 L | |
| Mass : | kilogram (kg) | 1000 g |
| tonne (t) | 1000 kg | |
| Heat : | Quantity of heat, work, energy | joule (J) |
| Heat flow rate, power | watt (W) | |
| Heat flow rate | watt/m2 | |
| U-value | watt/m2K | |
| Thermal conductivity (K) | W/mK | |
| Pressure : | Pascal (Pa) |
Facteurs de conversion :
| Multiply | by | to obtain | |
| Length : | metre | 3.2808399 | feet |
| metre | 39.370079 | inches | |
| Mass : | kg | 2.2046226 | pounds |
| tonne (t) | 0.9842206 | tons (long) | |
| tonne (t) | 1.10233113 | tons (short) | |
| Volume : | L | 0.219975 | gallons (Imperial) |
| L | 0.264173 | gallons (U.S.) | |
| L | 0.035315 | cubic feet | |
| Energy : | |||
| Quantity of heat : | kWh | 3.6 | MJ |
| kWh | 3412.0 | Btu | |
| MJ | 947.8 | Btu | |
| Btu | 0.001055 | MJ | |
| Heat emission or gain : | W/m2 | 0.317 | Btu/sq. ft. |
| Specific heat : | KJ/kgK | 0.2388 | Btu/lb. °F |
| Heat flow rate : | W | 3.412 | Btu/h |
| U-value, heat transfer coefficient : | W/m2K | 0.1761 | Btu/sq. ft.h°F |
| Conductivity : | W/m K | 6.933 | Btu in./sq. ft.h°F |
| Calorific value (mass basis) : | KJ/kg | 0.4299 | Btu/lb. |
| Calorific value (volume basis) : | MJ/m3 | 26.84 | Btu/cu. ft. |
| Pressure : | bar | 14.50 | lb.ft./sq. in. (psi) |
| bar | 100.0 | kPa | |
| bar | 0.9869 | std. atmosphere | |
| mm Hg (mercury) | 133.332 | Pa | |
| ft. of water | 2.98898 | kPa | |
| Specific volume : | m3/kg | 16.02 | cu. ft./lb. |
| Velocity : | m/s | 3.281 | ft./s |
Useful values
| 1 Therm | = 100 000 Btu |
or 29.31 kWh |
| 1 cu. ft. of natural gas | = 1 000 Btu | or 0.2931 kWh |
| 1 U.S. gal #2 oil | = 140 000 Btu |
or 41.03 kWh |
| 1 Imperial gal #2 oil | = 168 130 Btu |
or 49.27 kWh |
| 1 U.S. gal #4 oil | = 144 000 Btu |
or 42.20 kWh |
| 1 Imperial gal #4 oil | = 172 930 Btu |
or 50.68 kWh |
| 1 U.S. gal #6 oil | = 152 000 Btu |
or 44.55 kWh |
| 1 Imp. gal #6 oil | = 182 540 Btu |
or 53.50 kWh |
| 1 boiler horsepower | = 33 480 Btu/h |
or 9.812 kW |
| 1 mechanical hp | = 2 545 Btu/h |
or 0.7459 kW |
| 1 ton refrigeration | = 12 000 Btu |
or 3.5172 kWh |
In Canada, the value of 1 Btu (60.5°F) = 1.054615 KJ was adopted for use in the gas and petroleum industry. The ISO recognizes the value of 1.0545 KJ.