Does External Wall Insulation Reduce Energy Bills? If your heating is working overtime but your home still feels cold, chances are your walls aren’t doing their job. Without proper insulation, all that warmth you’re paying for could be escaping. For many homes, especially older properties with solid walls, around a third of heat escapes through uninsulated walls. This means a large portion of the energy you pay for is wasted, leading to higher heating bills and draughty rooms.
External wall insulation solves this problem by adding a protective layer to the outside of your home, trapping heat indoors and reducing energy waste, ultimately helping you save on your energy bills.
But is external wall insulation really worth the investment? How much can you actually save on your energy bills? In this blog, ‘Does External Wall Insulation Reduce Energy Bills?’, we’ll look at how heat loss affects your energy bills, compare energy costs before and after EWI installation, and answer the key question: “Is EWI Worth the Investment?”.
Content Page
- How Uninsulated Walls Increase Heat Loss & Energy Costs
- How Much Does an Uninsulated Home Cost to Heat?
- Does External Wall Insulation Reduce Energy Bills?
- Is EWI Worth the Investment?
How Uninsulated Walls Increase Heat Loss & Energy Bills
One of the main reasons for high energy costs is heat loss through external walls. In a home with uninsulated walls, around a third of heat escapes, making it harder to keep your home warm in winter and cool in summer.
The amount of heat lost depends on the type of walls your property has. Homes built before the 1920s typically have solid walls, meaning there’s no gap between the inner and outer layers. These types of walls lose heat very quickly, making insulation essential to prevent rising heating costs and energy waste. In contrast, homes built after the 1920s typically feature cavity walls, which include a gap that can be insulated to improve energy efficiency.
Since solid walls lose more heat than cavity walls, External Wall Insulation (EWI) is one of the most effective solutions for improving thermal efficiency and reducing energy bills. But how does it work? EWI reduces the energy needed to heat or cool a home by adding an insulating layer to the exterior walls. This helps trap heat inside during winter and blocks excess heat from entering in summer, leading to lower energy consumption and long-term savings.
How Much Does an Uninsulated Home Cost to Heat?
If your home has uninsulated solid walls, a large portion of the energy you pay for is simply sipping away. According to the Energy Saving Trust, homes without wall insulation can lose up to one-third of their heat through external walls. This means your heating system has to work much harder to maintain a comfortable indoor temperature, resulting in higher energy consumption and expensive heating bills.
To put this into perspective, here’s an estimate of annual heating costs for an average UK home:
- Detached house – £2,000-£2,500 per year
- Semi-detached house – £1,500-£2,000 per year
- Mid-terrace house – £1,200-£1,600 per year
- Flat – £800-£1,200 per year
For properties with poor insulation, these costs can be even higher, especially in colder winter months. Older homes built before the 1920s, which typically have solid walls, are particularly vulnerable to heat loss, making insulation a crucial investment.
Does External Wall Insulation Reduce Energy Bills?
Yes, installing EWI significantly reduces heat loss, meaning less energy is needed to keep your property warm. Studies by the Energy Saving Trust show that properly installed EWI can reduce heating costs by 20-30%.
The exact savings depend on factors such as the type of walls, property size, insulation thickness, and energy usage. In most cases, homeowners notice a significant reduction in energy consumption after installing EWI. It’s worth noting that every property is different, and it is not possible to determine the exact amount that can be saved. Below are some estimated reductions in average energy bills:
| Property Type | Estimated Savings (After EWI) |
| Detached House | £550 |
| Semi-Detached | £320 |
| Mid-Terrace House | £190 |
| Detached Bungalow | £240 |
| Flat | £150 |
Is EWI Worth the Investment?
Installing EWI comes with upfront costs, typically ranging from £8,000 to £15,000 for an average home. This includes materials, labour, and additional services such as scaffolding. The exact cost depends on several factors, including the size and type of the property, the choice of insulation material, and the desired finish. However, when considering the long-term savings, EWI is a cost-effective solution.
- Payback Period – If you save around £500 per year on heating bills, your EWI investment could pay for itself within 10-15 years.
- Increases Property Value – Homes with better energy efficiency ratings are more attractive to buyers and can get higher market value.
- Grants & Funding Options – Some homeowners may be eligible for government-backed grants, such as the ECO4 scheme, to help reduce upfront costs.
Additional Financial Benefits of EWI
While EWI requires an initial investment, it offers lasting financial advantages, including improved indoor comfort by maintaining a consistent temperature and eliminating draughts and cold spots, as well as long-term energy savings. Additionally, EWI supports environmental sustainability by reducing carbon emissions and overall energy consumption.
EWI Increases Property Value: Energy-efficient homes are becoming increasingly desirable in today’s property market. With rising energy costs, buyers actively seek well-insulated properties to lower future expenses. EWI enhances a home’s Energy Performance Certificate (EPC) rating, making it more attractive to potential buyers and potentially increasing its market value.
Lower Home Maintenance Costs: EWI acts as a protective barrier, shielding your home from weather damage, dampness, and mould. By preventing rain, wind, and temperature fluctuations from affecting the walls, it helps minimise the risk of cracks, moisture build-up, and long-term structural damage, ultimately reducing repair and maintenance expenses.
With energy prices continuing to rise, minimising heat loss is more important than ever. External Wall Insulation is a proven solution to reduce energy bills, improve home comfort, and enhance property efficiency all year round.
Thinking about insulating your home? At EWI Specialist, we provide expert external wall insulation and house rendering services. Contact us today to see how we can help you save on energy bills and keep your home warm all year round.
