The amount of energy represented by one gigajoule is equivalent to about 30 litres of gasoline, 39 litres of propane, 278 kilowatt-hours of electricity or 45.5 kilograms of coal. The average home in Alberta uses about 120 gigajoules of natural gas per year.Examples of average energy consumption for standard household appliances include: 1  40 gigajoules a year to heat a 40-gallon hot water tank for a family of four.2  4.3 gigajoules for a gas dryer processing 400 loads of laundry a year.3  4.2 gigajoules a year for natural gas range used two hours per day.xamples of average energy consumption for standard household appliances include: 1  40 gigajoules a year to heat a 40-gallon hot water tank for a family of four. 2  4.3 gigajoules for a gas dryer processing 400 loads of laundry a year. 3  4.2 gigajoules a year for natural gas range used two hours per day.