How to Stop Heat Coming Through Your Windows and Survive the Aussie Summer

That scorching summer sun can turn your home into an oven, especially when it’s beaming directly through your windows. Before you crank up the air con and watch your power bill skyrocket, there are smarter ways to tackle the heat at its source.

The most effective ways to stop heat coming through windows are by applying reflective window film, installing thermal blackout curtains, or using exterior shades. These methods work by either reflecting sunlight before it enters or providing an insulating barrier, significantly reducing heat gain and lowering cooling costs.

Choosing the right solution depends on your budget, how much DIY you’re willing to do, and the look you’re after. For the best balance of performance and aesthetics, reflective window film is a top choice. For the most budget-friendly and immediate solution, thermal curtains are highly effective.

To help you decide, here’s a quick comparison of the most popular options.

Installing window film involves thoroughly cleaning the glass, spraying it with a soap solution, applying the film, and using a squeegee to remove bubbles. This creates a reflective barrier that blocks a huge amount of solar heat before it can heat up your room.

Whilst we always recommend your window film is installed by a professional – because you won’t get any bubbling and it will ensure your windows look great and last a long time – we understand some people would like to attemp a DIY installation so here are the steps you can follow.

1. Gather Your Tools: You’ll need the window film, a spray bottle with water and a few drops of baby shampoo, a sharp utility knife, a squeegee (most kits include one), and a couple of microfibre cloths.
2. Clean the Window Thoroughly: This is the most important step. Any speck of dust or dirt will create a bubble. Scrape off any stubborn spots with a razor blade. Clean the glass and the frame.
3. Measure and Cut the Film: Roll out the film and measure it against your window. Cut it so it’s about 2-3 cm larger on all sides. You’ll trim the excess later for a perfect fit.
4. Spray and Apply: Generously spray the clean window with your soap solution. It should be dripping wet. Then, peel the backing off the film (a bit of sticky tape on each side of a corner can help separate it) and spray the sticky side of the film as well.
5. Squeegee and Trim: Place the wet film onto the wet glass. It should slide around easily. Once it’s in position, use the squeegee to push the water and air bubbles out, working from the centre to the edges. Use the utility knife to carefully trim the excess film along the window seals.

Feeling unsure? Before you commit to a whole room, buy a small sample roll of film. Apply it to a single pane on your hottest, west-facing window. Use an infrared thermometer (or just your hand) to feel the difference between the treated and untreated glass on a hot afternoon.

Mistake: Not using enough application solution, which causes the film to stick too early and creates bubbles.

Solution: Don’t be shy with the spray! The window and the film should both be completely wet to allow you to position it perfectly and squeegee out all the bubbles. Proper application is key, and understanding how home window tinting works can prevent common errors.

Yes, aluminium foil is highly effective at blocking radiant heat because its shiny surface is an excellent reflector of sunlight. For maximum effectiveness, the shiny side should always face outwards. Keep in mind, it doesn’t look attractive at all and can cause glare problems for those looking at the windows from the outside. So whilst it’s cheap, it should only be used as a short-term solution during a heatwave.

Taping foil directly to your window frames can leave a sticky residue or damage the paint. Use this method instead.

Materials: A roll of heavy-duty aluminium foil, a large piece of cardboard, and scissors.

• Step 1: Cut a piece of cardboard to fit snugly inside your window frame.
• Step 2: Wrap the cardboard completely in aluminium foil with the shiny side facing out. You can tape the foil to the back of the cardboard.
• Step 3: Simply wedge the foil-covered panel directly into the window frame. It will stay in place, block the sun, and can be removed in seconds without any cleanup.

Problem: The reflection from the foil is creating a blinding glare for my neighbours.

Solution: While foil is effective, its reflectivity is a known issue and to be honest, it will be a nigtmare for your neighbours or anyone looking at your home which is why we don’t recommend it. A better option in this case would be professional installed window tint that helps reduce heat inside a home.

Yes, thermal blinds work by creating sealed pockets of air that act as an insulator. This barrier reduces heat transfer, helping to keep heat out in summer and warmth in during winter. Cellular or “honeycomb” blinds are especially effective due to their layered cell structure.

In summer, closing your curtains definitely helps to keep heat out. A light-coloured curtain will reflect some sunlight, while a blackout or thermal-lined curtain provides a much stronger insulating barrier to stop the sun’s heat from radiating into your room.

Beyond heat, it’s also worth noting that professional UV protection window tinting can block over 99% of harmful rays, protecting your skin, furniture, and flooring from fading.

Sunlight heats your home in two main ways: through radiant heat (infrared energy you can feel) and conduction (the glass itself getting hot and heating the air inside). The absolute best solutions (like exterior shades and reflective film) block the radiant heat before it can even get through the glass.