By Bruce Key, member of Wodonga Albury Towards Climate Health (WATCH)
An area where most of us like to live lightly is spending money.
Heating our homes is a costly exercise and it is difficult to make a direct comparison between gas heating and electrical heating, but it can be done, and the result is interesting.
First, we need to compare the price at which gas and electricity are supplied. In Wodonga AGL charges 28.93c/kWh for electricity and they charge 4.28c/MJ for gas. That raises the first difficulty in making a comparison – gas energy is measured in MJ and electrical energy is measured in kWh. There is an exact relationship between MJ and kWh, being 1 MJ equals 0.278 kWh. Using that fact, the gas price becomes 15.4 cents/kWh which is about half the price of electricity. That comparison will apply if most forms of electrical heating are used, such as oil-filled panel heaters or under-floor electric heating.
However, to get a correct comparison it is necessary to take into account the efficiency of each form of heating. In the case of gas, about 20% of the heat goes up the flue and hence the efficiency is about 80%.
Heat pumps (split systems) are about 350% efficient because the electricity is not used to produce heat, it runs a pump which extracts the heat from the external air.
When we take efficiency into account, the comparison for a unit of heat energy produced to heat your house is as follows: Using gas to produce the heat costs 19.25 cents per kWh, using electricity costs 8.55 cents per kWh.
Thus, provided that a heap pump device is used to produce the heat, the cost of gas heating is more than double the cost of electrical heating.
If, in addition, it is possible to dispense with the gas connection and thus avoid the daily service charge of 98.12 cents/day, an additional $358 per annum will be saved.
My winter-time electricity consumption dropped by 79% when I turned off the electric floor heating and began to use a reverse cycle split system previously used for cooling only. That is a demonstration of the efficiency of a heat pump and why electric heating can be less costly than gas. There are heat pumps for hot water too.