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My Efficient Electric Home on the Central Coast

A guide to energy plans, insulation, windows, heating, cooling, solar, hot water, and lighting for an energy efficient electric home on the Central Coast.

My Efficient Electric Home on the Central Coast
Shea Cullen, Registered Architect at Good ArchitectShea CullenNSW Registered Architect 9748 · Updated 10 July 2026

Everything in this guide comes from working on real homes, like the sustainable retrofit we designed at Charmhaven, where better insulation, glazing and orientation cut the running costs to a fraction of what they were.

The order matters. Before you spend anything on the house, switch to a cheaper energy plan, because that costs nothing. Then, if you can only do one thing to the building, insulate the roof first, because it is where a home loses and gains the most heat and it is usually the cheapest place to fix. After that comes walls and windows, then the floor, then the appliances and the switch to all electric. The checklist below walks the whole sequence in priority order.

Go to the government comparison website Energy Made Easy (energymadeeasy.gov.au), enter your usage and switch to the cheapest plan. It is run by the Australian Energy Regulator, not a retailer, so every plan is listed. Then put a reminder in your calendar to do it again every year. Loyalty does not pay with energy retailers, the best prices go to new customers.
The roof contributes 25 to 35% of total heat loss or gain. Add ceiling insulation and sarking. Bunnings now stocks R6 insulation which is fantastic, or get a professional to install it. If you install it yourself, ensure all power in the house is off. There is an unfortunate history of fatalities from amateur roof insulators. If you can only insulate one thing, insulate the roof.
Walls contribute 15 to 25% of total heat loss or gain. Even brick walls can have insulation pumped into them. Insulation only does its job if the frame is not carrying the heat straight past it, so read what thermal bridging is before you spend. Pumped in insulation usually reaches an R value of about 2.5, go as high as the installer can achieve. If you are using pump in insulation, get the electrician to do their work first (unless they want to be showered in insulation) and seal any gaps first.
The floor contributes 10 to 20% of total heat loss or gain. Check what you have first. A concrete slab on the ground is not worth retrofitting. A raised floor with an open subfloor is worth a quote from the same company that does the roof and walls. If the subfloor is enclosed it may not be worth it, because that trapped air is already working as insulation. Use a hydrophobic material with as high an R value as possible.
If you can afford it, replace single glazed windows with double glazed. Is double glazing worth it on the Central Coast runs the numbers for our climate. If the budget is tighter, consider alternatives: external shutters or blinds, internal double cell honeycomb blinds, a pelmet above existing curtains to trap heat, a thermally efficient window film, or installing a second set of windows to make your own double glazing.
Look for a low U-value with a thermally broken frame, a timber frame, or a UPVC frame. How to decide which window to get covers the trade offs.
A reverse cycle air conditioner is generally the most energy efficient option for heating and cooling. If you are running oil heaters or bar heaters, replace them first, they are the most expensive way to heat a room and are usually what is blowing the bill out. Buy the highest star rating you can afford. Help it along with ceiling fans in each room and with natural ventilation on the days you do not need the machine at all. If you can install underfloor air conditioning, it is generally even more efficient.
Use the SolarQuotes website (solarquotes.com.au) to get quotes from vetted installers, there are cowboys in the solar market and this is the simplest way to avoid them. Check shading first, a heavily shaded roof may not be worth it. The federal government is currently paying a large part of the cost of a battery, and some retailers offer plans with three free hours of power a day which you can use to charge it. If your roof is an unusual material or a sprayed coating that might contain asbestos, ask the installers when you get quotes, they will tell you straight away whether panels can go on it.
Look for a heat pump hot water heater and set it to heat water when you are generating solar power. Hot water is usually the largest gas load in the house, and cooking is the other one worth switching.
Replace lighting with LEDs. They are more energy efficient. Look for lighting with a CRI of 95 or above so the colour rendering is as close to natural sunlight as possible. How lighting can change your life explains why that number matters more than the wattage.
When looking at houses, a basic thing to get right is to find a north facing house. North orientation lets you get sun in winter and keep it out in summer with the right overhangs.

Much of this list comes from real retrofits, like the sustainable retrofit at Charmhaven, which cut the energy bills to a fraction of what they were. If you are weighing up window upgrades, here is whether double glazing is worth it on the Central Coast, and for the design side of comfort start with passive design on the Central Coast.

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