For the last month or so it seems like the UK has been a bit of a divided camp – those who just can't get enough of this glorious heat and sunshine, and others (my dog included) who are just downright fed-up with it.
I actually fall into the former category – except for at bedtime when my furnace of a bedroom makes it nigh on impossible to get a good night's sleep. This is thanks to the fact that, from around midday, it is blasted with the full force of the sun. Even using all the methods for cooling down a room, such as closing the curtains, it remains almost unbearably hot.
While the fan I have blasting at my face brings some relief, I wanted a way of preventing the room from overheating in the first place – which is why I decided to try out some solar control window film. Here's how I got on.
What is solar control window film?
Solar control window film is just one method of preventing overheating, yet I had heard great things about its effectiveness. Before getting started I made sure I understood exactly what it is and what I could expect from it.
Chris Ruddock, solar panel expert and sales director at Centreco, explains how it works. "Solar window film is essentially a thin film that’s applied to the glass to help control how much solar heat, glare and UV light comes into a room. People often think of it as a heat-reduction product, but it can also help make a space more comfortable by cutting glare, and many films can also help protect furniture, flooring and soft furnishings from UV-related fading too."
Martyn Fowler, founder of Elite Renewables, has some more advice on its effectiveness. "South-facing rooms are usually where solar window film has the most noticeable impact because they get long periods of direct sun. The difference depends on the size of the window, the type of glazing, and the film specification. It’s not going to have the same impact as air conditioning, but it can reduce the intensity of heat and glare.
"Solar film can be used anywhere direct sunlight causes heat or glare," adds Martyn. "It’s a good option for large areas of glass, patio doors, skylights and rooms that overheat during summer."
Chris Ruddock is a solar panel expert and Sales Director at Centreco, a national leader in commercial solar energy systems with over 200 installations across the UK, offering expert insight into solar and battery storage solutions that help businesses save millions on electricity costs.
Founder of Elite Renewables, Martyn Fowler is one of the UK's leading renewable technology experts, working with heat pumps for the last two decades. His passion for decarbonisation matched with a deep technical experience of the technology make him one of the industry's go-to experts for all things renewable.
Which solar control film did I buy?
There are lots of different solar control films available to buy. I wanted one that would be easy to fit, affordable, but also effective. I'd heard of The Window Film Company before and, given that they have been around since 1998 and supply not just residential films but also commercial, they seemed like one of the best options. Additionally, they offer a whole host of different films for various needs and types of windows.
Micky Calcott, founder of the company, was also really helpful in recommending the best film for my needs, suggesting Climate 35 - Solar Control Film which comes with the following stats: Total Solar Energy Rejected: 68.0%; Glare Reduction: 60.0%; UV Light Rejected: 99.0%.
Micky also explained that what works for one space might not be right for another. "The right solar control film depends on your property and what you're trying to achieve. South-facing rooms that receive strong afternoon sun often benefit from higher-performance films, while other spaces may only need a lighter option to improve comfort and reduce glare.
"Some homeowners also prioritise maintaining natural light or preserving external views, so it's worth considering heat reduction, appearance and privacy performance before choosing the most suitable film."
My window is a triple casement window, and each casement is split into six small panes, each of which measure 290mm x 230mm. Handily, the film I used came supplied in five strips measuring 32cm x 152cm, designed to be cut with scissors before applying to the glass, then trimmed to the frame. Prices vary, but for a roll measuring 1524mm x 1m, expect to pay £58.20.
Micky Calcott is the founder of The Window Film Company, which he established in 1998 after working as a window film installer. What began as a one-person operation has grown into a business with more than 20 team members based at its head office. Almost 30 years on, the company supplies specialist window film and graphics solutions across a wide range of sectors, while its online shop serves hundreds of customers every week. Micky continues to focus on delivering quality products, excellent service, and building long-term relationships with customers
Shop other solar control films
This window film is made from PET, which is thinner and clearer than films made from PVC. This would be perfect for those after privacy as well as solar control as it has a one-way mirror effect. Additionally, it blocks 90% of infrared rays and 95% of UV rays.
Measuring H188cm x W61cm per roll, this window film promises to both enhance privacy as well as help prevent overheating. Rather than being self-adhesive, this one relies on static to stay in place – perfect for renters or anyone looking for a temporary solution during a heatwave.
Tinted black, this static cling film would be perfect for spaces such as south-facing conservatories in the the summer months. It offers 78% heat protection, blocks 88% of light and 92% of UV rays – the cutting grid on the back makes cutting straight easy.
How I installed the solar control film on my windows
I am not known for my methodical approach to DIY projects but this was a surprisingly simple task – made a little easier with an extra pair of hands, courtesy of my husband.
The film came complete with detailed instructions and the whole process was really straightforward from start to finish.
All you need to gather together before beginning is a pair of sharp scissors, a cutting knife such as a craft knife, and an empty spray bottle. You also need a clear, level surface on which to roll out and cut the film.
1. Get prepared
Before you start fitting the film make sure your window is spotless, removing every last trace of grease and grime. If you have mould on your windows, be sure to get rid of this too before you begin.
You will also need to prepare a solution of water mixed with a few drops of washing up liquid and add this to your spray bottle.
I then measured and cut my film to size, making sure to make it slightly bigger than needed for each pane, as instructed.
2. Remove the backing film
I'll admit that I found this next step a little tricky. The film comes with a clear backing sheet and you obviously need to peel this away before applying it to the window. I just couldn't seem to get a grip, but having done the first sheet, I got the hang of it.
Top tip: Remove the backing film slowly and carefully.
Just as when wallpapering a room, it helped to have a second pair of hands here to hold the newly exposed sheet of film while the next step got underway.
3. Applying the film to the window
Whether you are using film to insulate windows or reduce solar gain, you can't just go and stick the film straight to the window. First, you spray the entire surface of the film, and the window it is being stuck to, with the soapy water solution. The wet surfaces make it easy to slide the film around into the perfect position without it getting stuck to itself.
When it is just where you want it, spray it again and use a squeegee (which came included with my film) to flatten it out and remove any air bubbles.
"It’s a bit like applying a phone screen protector, but on a much larger and less forgiving surface," explains Chris Ruddock. "If you rush it, you’re more likely to end up with bubbles or creases."
4. Cut the film to size
Now it was time to cut away the overhanging edges. I used a craft knife but you could also use a more sturdy utility knife, which would also come in handy for jobs such as wallpapering around sockets. This part was far easier than I imagined. Using the straight edge of the squeegee made it simple to get an even cut.
Finally, I had to spray the window again and give it a final once over with the squeegee to ensure no air bubbles had appeared. Then, all there was left to do was to dry the whole thing off with paper kitchen towel.
From start to finish, the job took me just under an hour to complete.
Shop film fitting kit
No toolbox is complete without a good utility knife, and this one from Stanley is so easy to use. Blades are simple to change and the ergonomic design keeps knuckles out of the way.
Easy to fill and simple to use, this would be ideal for spraying your windows and film and, when you're done, it is perfect for helping with household cleaning jobs.
Perfect for all kinds of household tasks, these sturdy scissors are comfortable to hold, super sharp and make precision cutting easy. They're also made from recycled materials.
Results
On both the day before I fitted the window film as well as the day after, the outside temperature was hovering around 31°C. The day after fitting the film, I can honestly say that the bedroom felt noticeably less stuffy.
I placed a thermometer in the window to measure the 'before film' and 'after film' temperature and noted a reduction of 4°C.
While that might not sound like a huge difference, the whole room really did feel far more pleasant to sleep in so this was definitely a job worth doing for anyone looking at how to keep a house cool.
Pros and cons of solar window film
Like I said, the room felt cooler and somehow a little less stuffy after the window film had been fitted – so obviously that is a definite plus point.
Fitting was also simple and, unlike using other cooling techniques, such as shutting the curtains, light can still enter the room.
On the downside, while installation might be easy when working with small glazed areas, I imagine it could be trickier with larger expanses of glass, something Martyn Fowler agrees with. "DIY is fine for smaller panes, but I would be more cautious with large patio doors or when using to keep a conservatory cool. In those cases, a professional installer can check the glass is suitable, reduce the risk of thermal stress and get a much cleaner finish."
One other slight negative for me was the way it looked from the outside. Our bedroom is at the front of the house and the film makes the glass look a little gold. That said, the cooling effect meant I can live with this – plus I can always remove it once the cold and the drizzle returns.
FAQs
Does solar control window film work on all types of windows?
While the film has worked brilliantly for my windows, I was interested to learn from the experts that you do need to check that the product you use is suitable for the type of glazing you have.
"The main thing is to check that the film is suitable for your type of glass before you apply it. That’s particularly important if you have double glazing, triple glazing, Low-E glass, older windows or are using any specialist glazing innovations," says Chris Ruddock.
"Some darker or more reflective films can increase heat absorption in the glass, and if you use the wrong product, you could risk thermal stress or affect the window warranty. So, if you’re not sure, it’s worth checking with the film supplier, the window manufacturer or a professional installer before going ahead."
What other methods work to cool down south-facing rooms?
While solar control film can help tackle overheating, there are other steps you can take in order to keep your home cool, particularly in the case of rooms that face south.
"Solar film works best when it’s part of a wider cooling strategy," explains Chris Ruddock. "In a south-facing room, I’d also keep blinds or curtains closed during the hottest part of the day, then open windows early in the morning or later in the evening when the outside air is cooler.
"External shading can make a big difference too," continues Chris. "Certain garden sunshade ideas, such as awnings, shutters, pergolas or even planting outside the window can all help because they stop some of the sun reaching the glass in the first place. It’s also worth reducing heat from inside the room where you can, so avoid using ovens, tumble dryers or other heat-generating appliances during the hottest part of the day."
If you really want your home to stay cool in a heatwave it might just be time to consider fitting air conditioning or investing in a portable unit – there are lots of options for all kinds of needs and budgets these days. Having one of the best cooling fans to hand is also a bonus on the hottest of days.
