You can keep the heat out of your home by modifying windows to reflect light. There are several methods to achieve this effect: you can do something quick and easy with alfoil or a car sun shade, or you can do something more involved involving window film. In this recipe we'll first run through the quick and easy options, and then explain the window film approach.

• This recipe works by reflecting heat and light away from your home.
• Up to 80% of indoor heat gain in summer is through windows, so they are a key spot to target for improvements. 
• In addition to cooling your home and reducing energy costs, these measures can improve privacy in your home.

Quick and easy: car sun shade

You can attach a car sun shade to your window to reflect sunlight and heat back to where it came. This will be most effective on west-facing windows, as you'll block the evening sun. Sun shades are about $20, and they are easy to attach or remove. However, it's hard to cover your whole window, and if you do, you'll get less natural light entering. Also, from the outside it may look like you are a conspiracy theorist. 

Quick and easy: aluminium foil 

Alfoil is cheaper than a sun shade, and it allows you to fully cover the window area. Just be prepared for some strange looks from your neighbours! You can attach sheets of alfoil with tape, or use a spray bottle to wet the window, and you can stick the alfoil on and it will adhere through surface tension. Alfoil is remarkably good at reflecting heat and light, with the potential downside being a room that is darker, as well as cooler. 

Taking it to the next level: window film

Alternatively, you can stick removable window film to the window itself. These are adhesive sheets, applied directly to the windows, that reduce how much heat penetrates your windows. They can also reduce UV penetration, and improve heat retention in winter. 

Note that it can be tricky to install them with a smooth surface, so you may end up with visible creases that can be unappealing. It will also be hard if your window shape is complex or irregular. Also, while film is removable, it cannot be re-used once taken off. 

Instructions:

1. Prep: Measure the dimensions of your windows.
2. Purchase materials: Buy reflective window film that will sufficiently cover your windows.
   1. Check whether your chosen film is applied directly to the windows or to the window frames. 
3. Cut film: Trim the film to fit your window dimensions.
4. Apply: Follow the instructions provided, the films are likely to be self-adhesive but may require purchasing double-sided tape. You may need to use a scraper to remove air bubbles.

If you don’t want to install it yourself, you can have your reflective film installed professionally, but this can be quite expensive. Alternatively, you can ask your landlord if they would install the film for you.

Buying Guide:

• If you are buying reflective window film, there are two main types to consider. Dual reflective window film has reflective properties on both sides of the film. This is generally the better option to reduce indoor heat, and to make sure you can have clear views outside at night time. Mirror reflective window film can be more aesthetically pleasing than dual reflective film. However, it may also be harder to see outside at night time.
• Both options can be very effective at reducing solar heat gain and increasing privacy. We would generally recommend dual reflective window film as the better option. 
• You can buy reflective film instore or online from a lot of different vendors, including places like Temu, Luzen & Co, or Bunnings.