Block the sun’s rays and keep your home cooler, right? 

Using simple methods like applying blackout window film or installing heat blocking blinds sounds like a practical solution, in theory. 

A lot of homeowners look into or even experiment with DIY methods before choosing to use a professional solution in the end, anyway. However, because of the way glass responds to heat and temperature changes in general, tricks like using a reflective glass film or window tint are not only disappointing in their effectiveness, they can also lead to serious issues like glass cracks.

The fact is... 

What seems like a cheaper option for insulating your windows against the heat, often ends up being a waste of time and resources. Instead of putting hundreds into subpar fixes – that come with unwanted side effects – and then investing in a professional window upgrade anyway, take a look at the intrinsic problems in the methods that you thought were quick, simple, cheap heat blocking solutions. 

The more clarity you have about how to improve your windows, the more you and your energy bills will benefit in the long run.

Why a Home Window Tint or Blackout Film Won’t Work

Blackout window film will completely block out the visible light spectrum. It won’t, however, solve your summer overheating issues. 

If you want to stop anyone from being able to see within your home – and don’t want to look out onto your outdoor space – use blackout film, by all means.

If you want to reduce unwanted solar heat gain, don’t use blackout film. You’ll lose your ability to see the outdoors and all the mental health benefits that come with being able to see green trees and natural landscapes outside – and you’ll have to spend more to light your home with artificial light. Also, the dark colour can actually absorb heat, causing your window glass to heat up even more. 

What about a tinted sun blocking window film? 

You’ll be surprised to learn that tinted windows – even in double glazed units – are not a smart window insulating solution. 

When you tint your windows, either by using tinted glass or a tinted plastic film, you can end up with contrasting temperatures within your glass. Part of the glass will stay cool whilst the other surface will heat up, thus stressing the glass. Stressing your window glass like this can ultimately cause it to crack, leaving you with a much bigger problem.

Why Sun Blocking Curtains and Blinds Won’t Work

What about putting up a pair of specialised heat blocking blinds or curtains? 

The problem with this idea is that, first, just as with blackout film, you’re closing off your windows from natural light. In a sense, your windows are no longer ‘windows.’ And, you have to keep them blocked whilst the sun’s up to achieve any heat reduction benefits. Which means you’ll only be able to open your windows when it’s already dark outside.

The bigger problem comes down to the science of heat energy. When a material heats up, it naturally has to radiate that heat energy. So, when your glass heats up from the sun’s rays, even though you have expensive, high-quality blinds or curtains covering your windows, the heat is still going to radiate into your home.

Window dressings may slow the process, but because they don’t create an airtight seal, as is the case with double glazed windows, they can’t stop it.

What Reflective Glass Film Won’t Work

Another common DIY alternative option to professional window insulation is using a reflective surface, such as a special low E plastic film. Some people even try a homemade solution like aluminium foil, which has a shiny, reflective surface for light to bounce off of.

Does putting aluminium foil on windows keep the heat out? 

Aluminium foil will help to reflect visible light and some infrared light, but it isn’t going to stop your window glass from heating up and radiating heat. Not to mention this is one of the least aesthetically appealing ways to insulate your windows from the heat.

Low E film, which has a special low emissivity coating just like low E glass, will reflect some heat energy. However, it will also make your windows look foggy. And, window film is not a strong insulating material as it doesn’t create an airtight seal around the airspace, nor is it thick enough to have a significant effect or to stop some of your air conditioning from leaving through your single glazed windows.

Starting with Professional Heat Reduction from the Outset

Or, instead of messing with heat reflective window film, blackout plastic and blinds, you can just have the job done right and use double glazed windows. 

With double glazing, you’ll have two panes of glass separated by a sealed air space. The sealed space slows down heat, which stops it from entering your home. At the same time, the two panes of glass, tailored to the right thickness for your home, act as a hefty insulation barrier. With a low E pane of glass in your double glazing, you can enjoy incredible heat reduction benefits in the summer, and protection from heat loss in the winter, offering significant benefits year after year. The sun's energy will bounce back outside in the summer, and your indoor heating will stay inside in the winter.

Considering 87% of heat gain can come from your windows and skylights, you do need a worthwhile solution to save on energy bills and create a more comfortable indoor environment.

The irony is, you can save a lot of money by starting with a professional solution first. First, you won’t have to purchase rolls of specialised window film or pricey window dressings. Second, you don’t have to actually install new windows to get the window insulating benefits of double glazed windows. You can have your existing timber windows retrofitted, converting the frame and replacing your old single glazing with a double glazed unit, custom-tailored to your property’s unique needs.

Instead of dealing with the negative side effects of DIY tricks and not-so-effective alternatives, you get to enjoy the positive side effects – powerful window insulation all year round, significantly lower energy bills, the welcome relief of window noise reduction, and the prevention of moisture build-up for a healthier, quieter, more comfortable home.