If you live in the United Kingdom and your home uses gas for heating, cooking or water, your energy company will bill you in "gas units," either metric or imperial. Regardless of which of these units your energy company uses, however, they are meaningful only for the purposes of billing. If you want to measure your energy consumption in more universal terms -- kilowatt hours, for instance -- you can convert your consumption in metric gas units in just a few moments.
Convert your imperial gas units to metric gas units if you are billed in imperial metric units. Multiply imperial gas units by 2.83 to get this. If you used 145 imperial gas units, do this as follows: 145 * 2.83 = 410.35.
Multiple your metric gas units by the "volume conversion factor" of 1.022640 to convert from volume into energy. For the example gas units, do this as follows: 410.35 * 1.022640 = 419.64.
Use the "calorific value" to qualify energy units into electricity units. Multiply your energy value by 39.7 to do this. For your example gas unit reading, this would be 419.64 * 39.7 = 16,659.7.
Divide your electricity units by 3.6 to get kilowatt hours. If you start with 16,659.7 energy units, this would be: 16659/3.6 = 4,627.69 kilowatt hours.