How To Build an Efficient All Electric Home
An all electric home running on efficient appliances and a bit of solar is now the cheapest home to live in, and the most comfortable. The trick is spending in the right order, because every dollar of insulation you add first makes every heater and cooler you add later work less.
Here is the order I use, drawn from real retrofits where the bills dropped to a fraction of what they were.
Start with the building, then the appliances
It is tempting to buy a big air conditioner and call it done. But a leaky, uninsulated house makes even the best appliance work hard forever. Seal and insulate the shell first, so the machinery you add is small and rarely runs.
Orientation is part of this too. A home whose living areas already face north is warmer in winter and cooler in summer before you spend a cent on insulation, because it is heated and shaded by the sun on the right schedule. Insulation then holds that free comfort in.
One warning worth heeding. Insulation only works alongside good shading. Insulate a house but let the summer sun pour onto the glass and you trap that heat inside, turning the home into an oven, as Your Home puts it. The shell and the sun have to be managed together, which is why orientation and shading come first.
The order to make a home efficient and all electric
- 1
Insulate the roof first
The roof drives 25 to 35 per cent of all heat lost or gained, more than any other surface. Add ceiling insulation and sarking. If you do only one thing, do this. If you install it yourself, switch every circuit in the house off first, because there is a real history of injuries from amateur roof work.
- 2
Insulate the walls
Walls account for 15 to 25 per cent of heat flow. Even solid brick walls can have insulation pumped into the cavity. Seal gaps first, and let the electrician finish their work before anyone pumps insulation in.
- 3
Insulate the floor
Floors lose 10 to 20 per cent. Use a moisture resistant insulation with as high an R value as fits, especially over a subfloor or on a raised timber floor.
- 4
Improve the windows
Windows are the weak point in the shell. Replace single glazing with double glazing where the budget allows. Where it does not, external shutters, honeycomb blinds, a pelmet above the curtains to trap heat, or a good window film all help, as does adding a second sheet of glass to make your own double glazing.
- 5
Heat and cool with reverse cycle and fans
A reverse cycle air conditioner is the most efficient way to heat and cool almost every Australian home. Add a ceiling fan in each main room so you feel comfortable at a milder setting. Underfloor systems are more efficient again where they suit the build.
- 6
Switch hot water to a heat pump
Hot water is one of the largest energy uses in a home. A heat pump hot water system runs on a fraction of the power of an electric element. Set it to heat during the day so it soaks up your own rooftop solar.
- 7
Fit good LED lighting
Replace globes with LEDs, and choose ones with a colour rendering index, or CRI, of 95 or above so the light looks like daylight and the rooms read true. LEDs use around 80 per cent less power than the old halogen globes and last many times longer, so the switch pays for itself, and good light is cheap to run once they are in.
Common questions
If I can only afford one thing, what should it be?
The roof. It moves more heat than any other part of the house, between a quarter and a third of the total, so ceiling insulation is the single best value improvement you can make.
Is all electric really cheaper than gas now?
For most homes, yes. A reverse cycle air conditioner and a heat pump hot water system deliver several units of heat for every unit of electricity, and paired with rooftop solar the running cost drops well below gas. You also avoid the fixed daily gas supply charge entirely.
Does orientation still matter if the house is well insulated?
Yes, and the two work together. Insulation slows heat moving through the shell, but orientation decides whether the free winter sun reaches your living areas in the first place. A north facing, well insulated home needs the least heating and cooling of all.