In January 2025, the UK’s energy bill cap rose by 1.2%, causing many Brits to feel the pinch. However, Ofgem has since announced a whopping 6.4% increase in April, equating to an additional £111 per year for a typical household.
Although this amount is far lower than during the energy crisis when it reached staggering heights of £3,459 in October 2022, it’s still a 53% rise from when Ofgem first introduced the price cap in 2019.
Research from Money Advice Trust found that many Brits plan to make worrying sacrifices to lessen the financial pressure of winter energy bills. In the study, a whopping 6.7 million people intended to cut back on baths and showers, and 7.4 million were preparing to reduce their spending on essentials, such as food, toiletries and clothing.
However, there are various ways to make significant and long-term savings on energy costs through small tweaks to your home that don’t compromise but actually enhance comfort.
According to the Energy Saving Trust, around 18% of the home’s heat is lost through the windows. As window experts, we have compiled our top tips on enhancing your windows’ energy efficiency so you can save money and enjoy a cosy winter. So that you can work out what would have the best impact on your home long-term, we've also included the estimated annual savings and installation costs for each energy-saving method.
1) Double Glazing
Annual savings: £235
Installation costs: £300 to £5,000+ per window
The most effective way of retaining heat through windows is by swapping single-glazed windows for double-glazing — a window design with two panes of glass separated by a spacer bar filled with air or insulating gas. Triple glazing is believed to enhance energy efficiency further, but it’s debated whether it’s as necessary in the UK climate.
Double-glazed windows are now standard in most residential properties, but there are still plenty of homes with single-glazing if built before this change. Despite single-glazing losing heat doubly fast as double-glazing, it’s reported that around 7% of UK households still have no double-glazing.
The FMB (Federation of Master Builders) states that A++ rated double-glazed windows, the most energy-efficient, can reduce energy bills by up to £235 per year. However, the upfront supply and installation cost (which averages between £5,000 and £7,000 for a three-bed house in the UK) will likely put anyone off trying to reduce their outgoings.
As well as improved temperature control, the other benefits of double-glazing may make the cost worthwhile, including added security and enhanced resale value. However, due to the price, this option isn’t always possible. Additionally, if a property is listed in a conservation area, its original features, such as sash windows, must be retained.
Thankfully, double glazing isn’t the only option, and there are plenty of more affordable options to improve energy efficiency.
2) Secondary glazing
Annual Savings: £174
Installation costs: £100 to £550 per window
While double glazing is more effective, secondary glazing is far cheaper and easier to install. Instead of replacing the window units, this option only requires updating the existing windows with another glass or a plastic pane.
Some types of secondary glazing can be temporary, such as magnetic and lift-out, which typically cost up to £200 and £300 per window, respectively. Sliding and hinged glazing, costing up to £500 per window, offers a more permanent option that provides full access to the original window.
There are no chemicals or an airtight gap between the original window and the secondary layer, making the insulation much lower than double glazing. However, it’s still expected to reduce heat loss by 60% compared to single glazing.
Secondary glazing is predicted to lower energy bills by 10%, resulting in £173.80 for the typical household post-January 2025.
3) Thermal Curtains
Annual savings: £291
Installation costs: £18 to £115
A quick way to retain more heat in a house is to install thick curtains, preferably with a thermal lining. Heavy curtains form a barrier between the window and the room, preventing the heat inside from escaping and limiting airflow. These curtains are also fairly affordable, with some being available for as little as £18.
It’s been cited that well-fitted thermal curtains can reduce heat loss through windows by 27% and save an average home up to £291 on yearly energy costs.
Some ways to maximise the heat efficiency of curtains are to:
- ensure they don’t block radiators
- keep them closed at night time or on dull days when temperatures are lowest
- keep them closed on windows with no sun exposure
- open them during sunny spells to allow sunlight to enter the home
- get them made or tailored to the exact dimensions of the window
- hang them as close to the windows as possible
If you already own curtains and don’t want to replace them, you could alternatively add thermal insulated curtain linings to enhance their insulating properties.
4) Window Film
Annual savings: £74 to £350
Installation costs: £47 per square metre
Window films are an easy but effective way of maintaining a comfortable temperature during winter, as they act as an insulating layer and can reduce heat loss by 33%. Properties with both gas and electricity (including air conditioning), will see the most savings of up to £349.90 each year, totalling £1,749.50 across five years. Properties just using gas will likely see a smaller annual saving of £73.66. The performance level will also depend on the film type, installation quality and the existing windows.
Window films are thick laminate materials typically made up of multiple layers of polyethylene terephthalate (PET) and can be combined with metals, dyes, pigments, and more to provide benefits such as solar control, privacy, and security. Low-E window film is most recommended for retaining heat through winter, as it contains a special coating that reflects heat back into the room.
Self-adhesive window films are easy to install if you follow the provided DIY instructions, and there’s no need to remove the existing glass. However, professional installation can ensure no bubbles or creases occur, which can impact the insulation properties.
5) Draught-proofing
Annual Savings: £35
Installation costs: £3.49 to £50 per window
Draughts appear when there’s an accidental gap in a property’s construction. These air leaks may occur if a property is damaged, wasn’t built with enough insulation or from its natural settling. In windows, the gaps are often created by poor installation, cracks in frames from weather damage, or seals wearing over time.
A comfortable temperature is harder to maintain in buildings with draughts, as the warm air escapes through the gaps and cold air seeps through. The uncomfortable cold breeze can cause some to think the heating needs to be turned on for longer, hiking up the energy bills without achieving the desired warmth. Draught-proofing windows and doors can break this cycle and save up to £35 in yearly energy costs.
Self-adhesive foam strips are commonly used to draught-proof windows that open — they’re available for as little as £3.49 and are easy to install. However, they aren’t always long-lasting, so metal or plastic versions may be more suitable for enhancing durability but cost slightly more.
Before applying, cut the strips to the accurate size — too big and draught-proofing strips could get stuck, and if they’re too small, they won’t efficiently cover the gap.
Alternatively, you may need to consider professional draught-proofing at a higher cost of £50 per window if it’s difficult to carry out effectively yourself.
6) Sealant
Annual savings: £174
Installation costs: £5 to £53
Due to the sliding motion of sash windows, they require slightly different draught solutions, as the adhesive strips would likely come loose very easily. If the windows don’t open or don’t need to, applying silicone sealant is the most effective method to eliminate draughts.
At a small cost starting from £5, sealant is extremely cost-effective and is predicted to reduce energy bills by 10%. However, this is difficult to remove and makes the window inaccessible. It’s not advised to use if the windows need to open because they’re in a room where moisture builds, like bathrooms and kitchens, or they’re intended as a fire exit.
A larger investment is likely needed to experience the highest level of thermal efficiency. However, smaller changes like applying solar control window films and draught proofing strips can maintain a comfortable temperature with less reliance on central heating.
Get in touch with Evowrap for more information about how installing window films can help keep your home warm and reduce your energy bills this winter.