How to Keep Your House Cool This Summer: Can Your Windows Help?

Why your house feels hotter than usual

UK summers have been getting warmer, and many UK homes simply weren't designed with prolonged periods of heat in mind. If your rooms have been harder to keep comfortable this year, you're not alone,  it's something we are hearing more often as warmer weather is lasting longer.

The good news is that there are practical ways to reduce overheating, and they don't always mean replacing your windows.

Which matters more: keeping heat in, or keeping heat out?

The UK is still a cold and wet country for much of the year. That's why our homes - from insulation to glazing, have traditionally been designed to retain warmth rather than keep summer heat out. But warmer summers mean it's increasingly worth considering both. If you're choosing windows for the next 15 or 20 years, you need to think about keeping your home warm through winter as well as comfortable during periods of hot weather.

There isn't one answer that suits every home. The right balance depends on your property, how much direct sunlight it receives and what you need from your windows throughout the year.

Why energy-efficient windows still let heat in during the summer

Insulation and solar heat gain are two different things, and understanding the difference helps explain why a well-insulated home can still overheat.

A-rated double glazed windows are designed to reduce heat loss. Features such as low-emissivity (low-E) coatings, insulating gas between the panes and warm-edge spacer bars all work together to help keep warmth inside. That is useful during the colder months. 

Summer presents a different challenge. Solar energy passes through the glass and builds up as heat inside your home. So, even a window that performs very well at retaining warmth can still allow solar heat into a room on a sunny day, particularly in south or southwest-facing rooms and spaces with large areas of glazing, such as conservatories and bay windows. 

If a significant amount of unwanted heat is entering through your glazing, there are several ways to reduce it. The right option depends partly on whether you want to improve the windows you already have or are considering replacing them anyway.  

How can I stop a room overheating

1) Solar Control Film

Applied straight onto your existing glass, no window replacement needed. It uses thin layers of metal or ceramic material to reflect and absorb infrared and UV before it gets into the room.

It's generally the simplest, lowest-cost option to take the edge off a hot room, and a good option if your windows are otherwise in decent shape. It won't improve how well the window holds heat in winter, only how much solar heat it lets in during summer.

2) Solar Control Glass

A coating is built into the glass itself during manufacture rather than applied afterwards. It reflects a good chunk of solar radiation before it reaches your room, while still letting plenty of natural light through.

It's especially effective in spaces that catch a lot of direct sun, like conservatories.

How much difference can solar control glass make?

If you’re comparing quotes or spec sheets for solar control glass, you may come across a figure called G-value. It is a measure of how much solar heat passes through the glass, and a lower number means better heat rejection. It’s a useful thing to ask about if you’re weighing up options, but for most people, the more useful question is simply: how much cooler will this actually make my room?

If you’re comparing quotes or spec sheets for solar control glass, you may come across a figure called G-value. It is a measure of how much solar heat passes through the glass, and a lower number means better heat rejection. It’s a useful thing to ask about if you’re weighing up options, but for most people, the more useful question is simply: how much cooler will this actually make my room?

UP TO 10℃ COOLER

3) Vacuum Glazing

The newest technology in this space. Instead of the gas-filled gap used in standard double glazing, vacuum glazing removes the air entirely, creating a vacuum gap a fraction of a millimetre wide, which greatly reduces heat transfer through conduction and convection.

It's a genuinely clever option, particularly for period or listed properties where a bulky modern frame won't fit or won't look right. It's a newer technology that comes with a higher price tag and some structural and visual trade-offs worth weighing up properly before deciding if it's right for your home.

AT A GLANCE

Please note: costs are approximate, based on general research across UK suppliers, and intended as a general guide only. Heat reduction ratings (Mid/High/Very High) are relative comparisons between options rather than verified figures. Actual performance varies by product, specification, the size and orientation of the glazing, and the amount of direct sunlight.

FREQUENTLY ASKED QUESTIONS

Q. Does it matter which way my rooms face?

A. Yes. The direction your windows face affects when and how much direct sunlight they receive. South-facing rooms can be particularly uncomfortable later in the afternoon and evening. The amount of glazing matters too. Rooms with large areas of glazing experience greater solar heat gain than a smaller window facing in the same direction.

Q. Do I need to replace my windows to reduce summer heat?

A. Not necessarily. Solar control film can be applied to existing glazing, while solar control glass would usually be considered when replacing the glass or installing new windows. The best option will depend on the condition of your existing windows and what you're hoping to achieve.

Q. Does solar control film actually work?

A. Yes. Solar control film can reduce the amount of solar heat passing through your windows, which can help make rooms that receive a lot of direct sunlight more comfortable. How much difference it makes will depend on the type and quality of film, the amount of glazing and how much direct sunlight the room receives. It won't solve every cause of an overheating room, but if solar heat coming through the glass is a big part of the problem, it can be a relatively simple option without replacing your existing windows.

Q. Can solar control film be fitted DIY?

A. Yes. DIY solar control films are available and can be effective if fitted correctly. Professional installation may provide access to different products and can help achieve a consistent finish without bubbles, creases or uneven edges. Which route makes sense will depend on your budget, the size of the area and the finish you're looking for.

Q. Will solar control film change how my windows look?

A. It can. Some films are designed to have very little visible effect, while others have a noticeable tint or reflective appearance. Different products also provide different levels of light transmission and solar control, so appearance should be considered alongside performance.

Q. Can solar control film affect my window warranty?

A. Potentially. Applying film to an existing sealed glass unit may affect some manufacturers' warranties, so always check before installation. If you're unsure, speak to your original window installer or manufacturer first.

Q. How long does solar control film last before it needs replacing?

A. “Window film typically has a ten-year warranty, but it usually lasts much longer than that unless it’s physically damaged. It never fades, peels, bubbles or cracks, so it will provide solar protection for a very long time.”  – Paul Wilks, Arden Window Films

Q. Can solar control glass only be used in conservatories?

A. No. Solar control glass can be used elsewhere in the home, particularly where rooms receive lots of direct sunlight. There can be a trade-off between solar control, light transmission and the overall performance of the glazing. That's why it's important to consider the complete window specification rather than choosing glass based on summer performance alone.

Q. Will solar control glass affect how my windows perform in winter?

A. It depends on the specification. Solar control and thermal performance need to be considered together when choosing glazing. The aim is to find the right balance between reducing unwanted solar heat and maintaining good year-round performance.

Solar control film or solar control glass - which is right for me?

Of the three options covered above, film and glass are the two most people weigh up directly, since the real decision often comes down to whether you’re upgrading existing windows or replacing them entirely, vacuum glazing is a more specific technology, typically considered separately when a period or listed property is involved.

If your windows are still in good condition and you simply want to reduce the amount of solar heat entering a particularly warm room, solar control film can be a practical and relatively affordable option without replacing the glass.

Solar control glass is more likely to be considered when you're already replacing your glazing or installing new windows. It gives you the opportunity to choose the glass specification as part of the overall window, taking both summer solar control and year-round performance into account.

There isn't one option that's right for every home. The amount of glazing, the direction your windows face, your budget and the performance you're looking for should all be considered before deciding..

Talk to Finesse

Every home is different. The direction your windows face, the amount of glazing, the condition of your existing windows and how you use each room can affect the best approach. 

If you're struggling with rooms that become too warm in summer, speak to the Finesse team. We can look at your existing windows, discuss what could be contributing to the problem and talk you through the glazing options that may be appropriate for your home.

You can also visit our Birmingham showroom to discuss your home and see the range of windows and glazing we offer with a member of our experienced team.