How to Block Sunlight Heat from Windows [DIY Comparison] (2024)

The sun’s heat energy can warm your home to uncomfortable levels, especially in the summer. Instead of battling the unpleasant indoor temperatures with your cooling system and fans, learn how to block sunlight heat from windows. You’ll save every month on your energy bill, reduce your household’s carbon footprint tremendously and you’ll finally get to enjoy being in your home all year round.

Here's what you'll learn about:

1. Heat Blocking Window Shades
2. Blockout Roller or Panel Blinds
3. External Window Shading
4. Bubble Wrap Window Insulation
5. Heat Reducing Window Film
6. Combining Multiple Methods
7. The Ultimate Solution
8. Window Insulation Guide [Free Download]

There are plenty of ways to improve your indoor overheating problems, including cheap ways to block heat from windows. Some methods are more effective than others and, as with any DIY project, some are less aesthetically pleasing. But, through understanding and comparing all your options, from blockout blinds to bubble wrap and even sophisticated window solutions, you’ll have a clear idea of what you’re getting yourself into with each attempt to protect your home from that suffocating sunlight heat.

1. Heat Blocking Window Shades

Putting up window shades is a quick fix for solar overheating. It won’t solve the problem, but it will diminish the heat gain. You can install them yourself, making this an easy DIY solution. The trick is to use the right type of window shades to block the heat and to install them as close to the glass as possible to get the maximum benefit.

For insulation purposes, cellular or honeycomb shades are the most effective. The honeycomb shape helps to trap air, reducing your solar heat gain. You also may want to consider adding side tracks to your shades so they sit closer to the window and block out more heat.

Also, keep in mind the colour you choose. A lighter colour such as white or beige will help to reflect the sun’s rays. Depending on the interior colour scheme in your home, white honeycomb blinds may or may not look right. To solve any aesthetic issues, you can always hang drapes as well – although, by the time you purchase quality window sun shades, sidetracks and drapes, this will no longer be a cheap way to block the heat.

2. Blockout Roller or Panel Blinds

Another option for blocking out solar heat is to install blockout blinds over your windows. Blockout blinds are opaque, which means they don’t let any light pass through. Like heat blocking window shades, they offer a modest amount of heat blocking power – more so if they are closer to the glass, a reflective colour and are made from a high-quality material.

One huge downside of blockout blinds is that they are designed to stop light, not heat. This means they are ideal for keeping a room dark, such as for bedrooms with windows facing the rising sun. However, you’ll have to give up your natural light to enjoy any heat saving benefits.

3. External Window Shading

Another tactic you can use is to create shade outside your window. Depending on which approach you take, you may be able to create enough sun shade yourself, but you may also want a professional depending on how experienced you are with DIY projects. Plants and trees around the window will help to shade some light and keep the space directly outside of your home cooler. When plants lose water vapour, they cool the air around them.

You can also use awnings or eaves, installed over the window from the outside. This reduces the amount of sun that hits the window. It may help to consult a professional to make sure you’re putting the shading at the perfect angle to get the best results.

4. Bubble Wrap Window Insulation

If you want a truly low-cost solution and aren’t concerned about how your window will look, you can opt for bubble wrap window insulation – a doable option if you just want to temporarily block out the summer sunlight. Does bubble wrap on windows really work? Well, sort of. The bubble wrap increases your window’s insulating properties by creating a layer of still, trapped air.

Make sure the bubble wrap is tightly wrapped and sealed around the glass to get it to work. This ultra-cheap double glazing alternative can also help to insulate your windows from cold air in the winter, although don’t expect a huge difference. However, if you need a solution right now and don’t want to spend any money, bubble wrap can serve as your cost-effective summer or winter insulation kit.

5. Heat Reducing Window Film

What about using a special heat reducing plastic film? You can purchase a special insulating plastic film and apply it to your windows. When you attach it to the inside of the glass, it creates a small air space, similar to the plastic bubble wrap. Again, you won’t get a huge difference with this method, but if you get enough film to cover all your windows, you can block some heat from entering whilst still being able to enjoy the natural light.

6. Combining Multiple Methods

All of these DIY methods for blocking sunlight heat from windows will help in their own unique ways. However, none of them can pull off the complete job. For example, window covering ideas like blockout blinds and shades can’t stop sunlight from hitting the glass from the outside. This means, even though you’re slowing the heat from passing through and around the window dressing, once the glass heats up from outside, the heat energy is there and will inevitably seep into your home.

Outdoor shade solutions are an excellent partial solution and with added greenery you can also enhance the aesthetic of your home. However, as the sun moves (technically as the earth moves), the angle of the sunlight will change, which means at some times of the day, you're still getting unwanted heat gain.

Plastic film and bubble wrap serve as a cheap double glazing job, but they aren’t that effective and they aren’t pretty to look at. With bubble wrap in particular, you can’t actually see outside your window. Which means you’ll have to say goodbye to your views of the outdoors.

By combining two, three or more of these methods, you’ll enjoy the best impact. If you really want to do it yourself, installing blinds or shades, applying plastic and working on developing outdoor shade, when all combined, will help. But, your windows are likely to appear chaotic, you will still have flawed heat blockage, and all the money you were trying to save – you’ve just spent on layers of cheap DIY methods.

You can still get the benefits of double glazed windows without having to make a huge investment.

Window technology has taken a few leaps forward in the past few years. Today, windows can be retrofitted instead of replaced for a fraction of the cost of new double glazed windows. This means your existing timber frame remains, but the single glaze that’s causing all your overheating is replaced by a tailored double glazing unit. Thermawood uses a special patented dry retrofit process that also helps to reduce moisture build up, leaving your home comfortable and protecting your indoor air quality.

This means less financial outlay, no DIY headaches and substantial heat blockage – not to mention the insulation benefits when the weather cools, the noise reduction benefits and the value you’ll add to your property.

Barbara, Another Satisfied Thermawood Customer Had This to Say

"I have been looking for an affordable and high-quality double glazing system for over 5 years. Each time I asked for quotations I was disappointed with the technology let alone the huge cost. It never made sense to me to replace perfectly fine existing window frames as this is very labour intensive and costly."

"When I learned about the technology used by Thermawood I thought that this made perfect sense to me. They replace the glass component of the existing window rather than the window frame and window itself."

"This technology has been successfully used in New Zealand for 40+ years. It allows homeowners to provide better insulation from heat/cold/noise as well as reduces the chance of wood rotting, draft etc. and it is also VERY cost-effective."

"Mark and his team are very professional, arrive on time, get things done, and do not leave any mess behind them. They are friendly to owners as well as neighbours, and work hard to get the job done in the shortest possible time. I can recommend Mark and Thermawood to anyone who is looking for a system that reduces heating/cooling bills at a very affordable price."