Add thelocalreport.in As A Trusted Source
When temperatures drop across the UK, the first thing homeowners will notice is how quickly heat loss becomes a problem in homes. In most homes the thermostat is turned up and the boiler is expected to keep pace. But during the cold, the real problem in many homes isn’t how powerful the heating system is – it’s how quickly the heat goes out.
older or underperforming windows Windows are one of the biggest culprits of heat loss, and during winter, they can make it very difficult to keep your home warm. When the mercury drops below zero, old or single-glazed windows can quietly increase your energy bills.
With heating costs in the UK still high by historical standards, upgrading your windows has become one of the most cost-effective ways to keep your home warm and reduce your reliance on central heating. And in the cold season, the difference between old glazing and modern energy-efficient windows becomes even more obvious.
Get a quote for double glazing your home
Use our comparison tool to get a range of free quotes from leading UK Window Installer,
How much heat are your windows really losing?
To understand the reasons behind heat loss in homes, it helps to start with what can be the main culprit in most properties: windows.
It’s common to think of heat loss in terms of roofs, walls or floors, but windows can account for a large portion of wasted energy. Estimates from industry bodies such as the Energy Saving Trust suggest that around 18 to 25 per cent of a typical home’s heat is lost through its windows.
This is partly because glass is inherently a poor insulator, and partly because older windows – especially those installed before the early 2000s – were not designed to the efficiency standards required by building regulations. A key measurement is the “U-value,” which tells you how easily heat passes through the window. The lower the U‑value, the better the insulation.
Single-glazed windows typically have a U-value of 4.5 W/m2K or higher, which means heat flows faster through them. Older double-glazed units from the 1990s often sit around 2.8 to 3.0 W/m2K. In contrast, modern A-rated double glazing can reach around 1.2 W/m2K, while triple glazing can drop to about 0.8 W/m2Of.
In practice, this means that many older windows allow far more heat out than homeowners would like, especially during prolonged cold weather. A modern window can retain heat two to three times more effectively than the glass still in place in many UK homes.
Cold weather makes ineffective windows even more expensive
Extreme weather highlights how much window heat loss can affect both comfort and your heating bills.
When the outside temperature drops significantly, the rate of heat loss through windows accelerates. The difference between 5C outside and 21C inside is substantial, but when it is -5C outside, the temperature increases dramatically, accelerating heat transfer. This is why dryness, cold and cold spots become more noticeable in rooms due to cold.
A typical three bed semi-detached house with 15 or 20 year old double glazing is losing far more heat than the homeowners realize. The signs are often subtle in mild weather but unmistakable during cold weather.
Look for:
- constant condensation inside the glass
- cold air around the frame or sill
- Rooms that are much cooler than others
- Black mold that forms around a window opens up or cracks open
- Rattling glass or apparently failed seal (clouding between layers of glass)
During cold weather, these problems force your boiler to work harder and cycle more often, increasing energy use and increasing your heating bills.
How much can you save by replacing old windows?
Savings vary depending on the type of property, window size and frame material, but industry guidance provides some useful benchmarks. According to Energy Saving TrustReplacing single-glazed windows with modern double glazing can save around £140 to £235 per year on heating bills in a semi-detached home, and potentially more in larger properties or in particularly cold areas.
Even upgrading old double glazing to new A-rated units can make a meaningful difference. Although the cash savings may be less than single glazing, homeowners may notice notable improvements in how warm rooms feel and how less often the heating needs to be turned on.
Importantly, efficiency is not just about glass. Modern windows provide a tight seal against air leakage, meaning less warm air escapes around the frame, a factor that can greatly improve comfort during severe cold.
Why do new Windows perform so much better?
Even though your existing windows may not look particularly old, the technology behind them may be decades old. Much of the UK’s housing stock still relies on glazing installed in the 1990s or early 2000s, long before today’s stringent efficiency standards. Modern windows are engineered not only to keep heat in, but also to manage condensation, reduce air leaks, and maintain a steady indoor temperature – all things you notice right away when it’s cold.
Window technology has advanced significantly over the past two decades. Today’s units combine several features specifically designed to reduce heat loss:
- Low-Emissivity (Low-E) Glass: A transparent coating reflects heat back into the room instead of out.
- argon filled gaps: The space between the panels is often filled with argon gas, which is more insulating than air.
- warm-edge spacer: These materials reduce heat transfer around the perimeter of the glass, where heat loss was greatest.
- Multi-chamber UPVC frame:Additional interior compartments provide more insulation.
- thermally broken aluminum frame: Modern aluminum windows now include insulating sections that prevent heat conduction through the metal.
Since 2002, building regulations require very low U-values, meaning that any window installed in the last 20 years is likely to be significantly more efficient than any window older.
What to consider when choosing replacement windows?
If you’ve decided that your windows need to be upgraded, the next challenge is to decide which type is right for your home. The UK market is full of different ratings, materials and glazing options, and it is not always clear which features actually improve efficiency and which are merely marketing terms. A good installer should help explain the technical details, but it’s useful to understand the main options before you start comparing quotes. double glazing companies,
If you’re thinking about upgrading your Windows, there are several viable options to choose from.
- energy rating: Look for A‑ or A+‑rated windows BFRCThey offer the best balance of insulation and value,
- double vs triple glazing: Double glazing is usually sufficient for most UK homes, but triple glazing may be worthwhile in very cold areas or for homes seeking exceptional noise reduction.
- frame material: UPVC is economical, low-maintenance and highly insulated. Aluminum offers a thin, modern look and excellent durability when thermally broken. Wood is often required for conservation areas and listed buildings.
- certificate: Select installers registered with FENSA Or FixedEnsuring that the installation conforms to building regulations.
- Cost: Expect to pay around £600 to £1,000 per window for new UPVC double glazing, depending on the size and style.
If you can’t replace your windows right now
If full window replacement is not an option, there are still practical steps to take to reduce heat loss and help keep your home warm during severe weather.
window replacement This is a significant investment, but there are temporary ways to reduce heat loss during winter:
- Install draft-proofing strips on the frame
- Use thermal or heavily lined curtains
- Add Temporary Secondary Glazing Film
- Seal visible gaps with silicone or expanding foam
- Check that trickle vents are closed during extreme cold
These measures will not match the performance of new windows, but they can provide a significant improvement in comfort during cold weather.
Cost-effective energy upgrades in cold weather
With unpredictable winters increasing in the UK, replacing old windows has become one of the most impactful home improvements you can make. It reduces heat loss, lowers your energy bills, and makes your home more comfortable when the temperatures drop.
While many energy-saving upgrades work behind the scenes, new windows have an immediate, tangible impact. And during the cold winter, the difference between old glass and modern glazing is something you feel every time you enter the room.
Upgrading your windows won’t stop the snowy weather outside, but it will help ensure that the majority of your heating stays where it belongs: inside your home, keeping you warm.