With many parts of Australia sweltering through hot and humid weather, here are some tips to keep your home cool and energy bills low

With many parts of Australia sweltering through hot and humid weather, here are some tips to keep your home cool and energy bills low
  • PublishedJanuary 26, 2024

Australia certainly hasn’t been immune to the scorching sun this summer. 

A wave of hot weather has seen some regions swelter through temperatures in their mid-40s this week, triggering heatwave warnings.

And now with NSW, SA, WA, and QLD in the firing line, many of us will rely on the trusty aircon — at 21 degrees Celsius, 24 hours a day — to keep us cool.

But this doesn’t come without a cost, and a hefty one at that.

So, if you’re looking to avoid the post-summer bill shock, here are some ways to stay cool while saving energy and money.

Avoid setting your air conditioner too cool

While it may feel like it, you don’t need an arctic breeze to keep you from sweating in summer.

The harder your aircon has to work, the more electricity it will consume. That means the lower you set the temperature when cooling your home, the higher your electricity bill will be.

Energy Efficiency Council head of strategy and partnerships Holly Taylor says in an Australian summer, setting the aircon at 24 degrees Celsius is the optimum temperature.

“Not only will setting the thermostat at that temperature save you money, it’s also better for you as transitioning from very low indoor temperatures to high temperatures outside [and vice versa] can be a shock,” Ms Taylor said.

“Plus, every degree lower on the thermostat can increase your bill by as much as 15 per cent.”

A lady holding an aircon remote control and pointing it towards the unit system on the wall
To save on power bills and keep yourself cool simultaneously, keep your air conditioner set at 24 degrees Celsius.(FreepikFreepik)

As a general rule, your system shouldn’t be more than eight degrees below the outdoor temperature. For example, if it’s 32 degrees Celsius outside, your aircon temp shouldn’t be cooler than 24 degrees Celsius.

To give you an idea, here’s how small changes to the cooling temperature can make a difference to cost using the Ergon aircon cost calculator.

Annual cooling costs based on four hour per day run time for 16 weeks per year

Cooling capacity21 degrees22 degrees23 degrees24 degrees

*Assumes 33.25c/kWh electricity usage rate (Tariff 11 – Ergon Energy network)

If a ducted or split system air conditioner isn’t something you can install in your home (especially for those renting), a portable air conditioning unit or a pedestal fan could do the trick.

And remember, if you do end up using your aircon, block off the rooms and spaces that don’t need temperature control.

Read on to find out how this hybrid aircon method uses 70 per cent less power.

Close gaps and cracks around the house

It might be time to adopt a door snake.

No, not a real snake. Just a long, stuffed fabric tube that prevents a draft from entering a room.

Whether you’re a renter or home owner, draught proofing your home offers bang-for-very-little-buck, says Ms Taylor.

“Air leaks under and around doors, windows, ceilings, and skirting boards make big differences,” she said.

“Draft proofing is cheap, easy to do in most homes, and delivers outstanding results in terms of keeping warm air out in summer.”

An illustration of the inside of a house with arrows pointing to specific areas people should look at for draught proofing
Look at the following areas of your home to identity potential air leaks that can be closed up.(Supplied: Sustainability Victoria)

Energy Australia suggests households can save up to 25 per cent on every energy bill by reducing the amount of air leaking from gaps and cracks.

Consider installing insulation

If you’re looking for more of a long-term investment, roof insulation can act as a barrier to heat flow and reduce the internal temperature of a house.

Energy Victoria says effective ceiling insulation can save a household up to 20 per cent on cooling and heating costs.

If you’re unsure whether your ceiling insulation is working as effectively as possible, check for the following signs:

  • Drafts are present
  • Your home has difficulty maintaining a temperature
  • Energy bills are higher than usual
  • Mould or pests hiding in the ceiling
  • Your home gets excessively hot in the summer

And if your insulation turns out to be in dire need of a top-up (or maybe even a complete reinstallation), make sure to consider:

  • The two types of insulation — bulk insulation and reflective foil insulation
  • Selecting the right R value — measure of a material’s resistance to heat flow
  • Employing a professional for help

Use your trusty old fan

Nothing says Australian summer quite like a fan running to keep you cool after a long, hot day.

According to the Australian Department of Climate Change, Energy, Environment, and Water (DCCEEW), fans can improve comfort levels by about three degrees.

“They are a low to medium cost to buy and are cheap to run at only around two cents per hour.”

But keep in mind fans cool people, not rooms. So turn them off when you’re not around.

“While electric fans do not cool air or reduce humidity, they provide air movement that helps us feel cool and use less energy than evaporative coolers or air conditioners,” a DCCEEW spokesperson said.

Shut up the house during the hottest hours

If your first thought on a hot day is to open the house up for some ventilation, you may want to think again — you’re essentially inviting the heat and humidity in.

What you want to do instead is open your windows at night to let the cool air in, and then close them first thing in the morning to help trap the cool air inside.

Energy NSW says closing curtains and blocking out heat can save a household $50 a year.

Ms Taylor also recommends installing external window coverings such as adjustable awning blinds and shade sails.

“In summer, it’s more important to keep direct sun from hitting your windows by putting up shade on the outside,” she said.

“This is especially true for west-facing windows, and is good practice even with double-glazed windows which can still let in heat.”

Adopt a few shade screen plants

Turns out, strategically planting the correct mix of trees against windows and walls can help you block heat and save you money on cooling costs.

For this to work effectively, climbing plants, deciduous shrubs, or small trees should be positioned outside your house, blocking the sun before it hits windows or external walls and heats them up.


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