The role your windows play in energy efficiency is clear as day

If you’re looking to improve the energy-efficiency of your home, but your property is unsuitable for a heat pump and you’ve completed an upgrade of your insulation, then perhaps it’s time to shift your thinking from brickwork to glassware.

The windows in your home have a significant impact on the bills you pay every month. Their size, the airtightness of the frames, and of course the number of layers they comprise, are all factors in the amount of heat they allow to escape from your home.

However, energy-efficient windows are not cheap and require – as always – a wider understanding of the processes involved in heating your home in order to give you a real return on your investment. In terms of cost effectiveness, changing windows on their own will have a very low impact on the EPC as it only adds a few points: insulation will lift your EPC score much higher.

It’s also worth noting that while the cost of installing new windows may take a while to be recouped through lower energy bills, it will have an immediate impact on the resale value of your home; adding figures as high as 75 percent of the initial installation fee.?

Triple glazing remains relatively rare in the UK, but with energy efficiency regulations in England likely to require windows in new homes to have a U-value of 0.8 or below after 2025 (see breakout), we can expect to see this impact the private rental sector in time. With EPC C the standard for future rental homes, many landlords will be considering new windows as a worthwhile measure to protect their investment. It provides better insulation than double glazing by introducing an extra pane of glass between the two panes, creating an additional cavity that can be filled with a gas such as argon – or simply air. This improves the insulating quality of the window by up to 35 percent, and as any good heat-loss assessment will tell you, insulating windows remain one of the most cost-effective solutions for bringing down those energy bills.

?

If I buy today, what will I see tomorrow?

Window development is big business. While London’s soaring glass towers indicate a trend that shows no sign of stopping, the premium we put on letting the outside into our homes is no different.

Some alternatives, such as vacuum glazing already exist. Here, two panes are held very closely together but with a vacuum between them. This enables it to be slimmer than other types, potentially enabling it to fit double glazing apertures without losing the low U-value. However it remains a particularly expensive option.?

When we’re talking about the ability of windows to retain heat, we’re talking about ‘thermal transmittance’, also known as ‘U-value’. The greater the rate of heat transfer through a structure, whether single material or composite, the higher its U-value (accounting for temperature difference on either side).?

To help you visualise this, the double glazing found in 85 percent of UK homes typically has a U-value of around 1.2. By switching to triple glazing you can reduce the U-value for your window to less than 0.5.

Other efforts to create more narrow triple-glazed windows include reducing the width of the central pane. Corning’s use of ATG (Architectural Technical Glass) is one example of this.

Water-filled windows are being developed around the world, notably in the UK by Loughborough University researchers. These use a pipe system to circulate water through the window panes, maintaining a regular core temperature and potentially redistributing collected heat. Early tests have shown U-values of lower than 0.5 and we can expect to hear more on this technology following a pilot scheme.

Wherever the technology takes us, from 2025 onwards triple glazing is likely to become the standard for new build properties, development widely considered crucial to mitigating heat loss in our homes.

For homeowners in the PRS it remains a practical and affordable solution to reducing our tenants’ energy bills, provided it is built into the redesign as part of a wider assessment of the way our homes are heated.

And remember, any efforts spent sealing your property must be complemented with an increased focus on ventilation. The greater your airtightness, the greater the chance of condensation and the creation of mould and complications arising from moisture.??

?

Remember the following considerations when upgrading your windows:?

• Triple glazing doesn’t only insulate against heat, it also provides greater sound insulation – a viable solution for homes located on a busy road
• Triple glazing is more difficult to break through than double glazing, if security is an issue
• Switching your old double glazing out for new triple glazing typically requires a new frame to accommodate the greater width, which adds to the cost of installation
• To be sure of the most energy-efficient window options, look out for the BFRC rating – the UK’s most widely used measure of energy performance in windows and doors
• North-facing rooms don’t benefit from the natural light and warmth of solar gain. Therefore the cost of heating a room with no direct sunlight can be considerably more. It’s worth prioritising these windows first
• You don’t have to do it all at the same time. If there are particular cold spots in your home around inefficient or poorly insulated windows, focus on removing those first

?

To learn more about energy efficiency solutions for your home, including how to book a home assessment and finance installations through relevant national and regional grants and funding, contact The Green Landlady.