29 June 2026
As summer temperatures continue to rise, many homeowners are looking for ways to keep their homes comfortable without relying on fans and air conditioning. While blinds, curtains and ventilation all play an important role, one of the most effective ways to reduce heat gain is often overlooked: your timber windows.
If you are struggling to keep cool through another heatwave wondering what you can do beyond drawing the curtains, this guide from SashWise is for you.
Well-designed timber windows do not just look beautiful, they also provide excellent insulation, helping to keep your home cooler in summer and warmer in winter.
Windows are one of the main ways heat enters a property. Direct sunlight passing through glazing can quickly raise indoor temperatures. While older or poorly fitted windows may allow warm air to seep inside through gaps and draughts.
During a heatwave, this can make your home feel stuffy, uncomfortable and expensive to cool.
Timber is a naturally insulating material. Unlike aluminium, which readily conducts heat, wood has low thermal conductivity, meaning timber frames do not readily absorb heat from the sun and transfer it into your home.
An aluminium frame in direct sunlight will become searingly hot to the touch, and that heat conducts inwards. A timber frame under the same conditions stays considerably cooler, acting more like a buffer than a conductor.
During a heatwave, the difference between a stuffy house and a liveable one often comes down to ventilation.
Timber windows, particularly traditional sash windows, are specifically designed to exploit something called the 'stack effect'. Here is how it works:
Hot air rises and accumulates near the ceiling.
By opening the top sash, that hot air escapes outward.
Simultaneously opening the bottom sash slightly, cooler air is drawn in a floor level.
This creates a continuous circulation without any mechanical assistance.
Sash roller stop locks facilitate this whilst not compromising on the security of the window.
This is why Georgian and Victorian townhouses built almost entirely with timber sash windows were remarkably liveable before air conditioning existed.
Today's timber windows are typically fitted with high-performance double glazing.
The double glazed units are filled with Argon gas between the panes of glass. This inert gas acts as an insulating layer, slowing the transfer of heat from outside to inside.
All SashWise windows include low-emissivity (Low-E) coating, a thin metallic coating applied to the glass that reflects radiant heat while still allowing natural daylight through.
The timber window frame provides a thermally stable, low-conductivity surround, while the glazing unit controls what the sun's radiation does once it reaches the glass. Together, they outperform many cheaper window alternatives.
Older timber window often develop gaps around the frames where they have warped over time, allowing warm air to enter the property even when the window is shut.
Our new timber windows are manufactured to precise tolerances and fitted with high-quality weather seals that significantly reduce unwanted air leakage.
Improving window seals does not have to mean replacing your window. It is possible for us to retro fit seals to old windows as part of draught-proofing service, to learn more about what this entails visit the dedicated webpage.
Your windows work best as part of an overall strategy for reducing heat gain. During a heatwave, consider:
Close curtains, blinds and shutters on south and west facing windows during the day.
Open windows early in the morning and later in the evening when outdoor temperatures are lower.
Keep internal doors open to encourage airflow throughout the property.
Use sashes correctly, the top sash slightly down, bottom sash slightly up to create stack ventilation.
Heatwaves are becoming more frequent in the UK, making it increasingly important for homeowners to consider how their property performs in warmer weather.
Modern timber windows offer an attractive combination of natural insulation, advanced glazing and excellent weather sealing, helping to reduce heat gain while maintaining the character and appearance of your home.
Whether you are renovating a period property or upgrading your existing windows, our high quality timber windows can provide year-round comfort, improve energy efficiency and lasting value - keeping your home cooler in the summer and warmer when winter returns.
Feel free to contact us now to find out how SashWise can help you find the right solution to keep your home cooler.
