Reduce gas bills by insulating your home

5 Oct 2022
9 min read
Reduce Gas Bills by Insulating Your Home

The information provided was correct at the time of publication.  Some incentives and grants may no longer be available.

By insulating our homes, we reduce the demand for energy and burn less fuel, which helps save money on bills, combat climate change and protects the planet.

Insulating the loft, walls and floor of your home is a great way to reduce energy use every year from a one-off activity. The average UK energy bill in 2021 was £1,200 per year however, in October 2022, the Government’s Energy Price Guarantee was set at £2,500. It’s important to note this is an AVERAGE price. If you use more than average amounts of energy, you will pay more. So it makes sense to reduce usage and stop energy escaping from your home as much as possible.

Heating and hot water account for around 80% of our home energy consumption. Around 50% of heat in a house escapes through the roof, walls, windows and floors if a building is not insulated.  Insulation is the equivalent of putting a big warm blanket around your house and it doesn’t have to be expensive or difficult.   

There are lots of low-cost energy conservation measures to fix the problem of heat loss through walls or floors

A staggering 16 million UK homes don’t have the recommended 30cm of loft insulation and because insulation is ‘invisible’ in walls or under the floor it’s doesn’t always spring to mind when considering energy efficiency measures.

There are lots of low-cost energy conservation measures to fix the problem of heat loss through walls or floors, many of them are quick, easy solutions. Energy efficiency – particularly through insulation – is a way of saving energy at home and improving your comfort whilst cutting your energy bills. Quite simply, you can fit and forget them. A guide to costs, savings and carbon dioxide emissions avoided for a typical home is provided at the bottom of the page for each measure.

Roof Insulation

Insulate your loft to a standard depth of 30cm, which is the length of a school ruler. This is probably the easiest and most effective way to keep heat in your home and stop it escaping into thin air! Rolling out mineral wool or another product in your loft, will last for around 40 years and have a pay back of about one year so is a fantastic investment.

Many people choose to fit the insulation material such as mineral wool themselves and this handy video explains how. If you have the rolls fitted by an installer, ask that they fit some boards over the insulation and near the loft hatch so, you can still store Christmas decorations in the roof. 

How to Lay and Fit Loft Insulation

This handy video below explains how.

Wall Insulation

Modern homes are increasingly efficient and air tight. If your home was built after 1990, the good news is it will have had insulation added during construction.

However, this is not true for the majority of houses in the UK. Over 5 million homes have uninsulated cavity walls and only 8% of the 8.5 million homes with solid walls have been insulated; there is huge potential to reduce heating bills for families living in these homes.

Cavity Wall Insulation

If your home was built between 1930 and 1990 it is likely the construction method used was two brick walls built with a gap in between. This cavity wall structure originally had no insulation.

Filling a cavity wall is quick and easy and there may be a Government grant available if you are on certain benefits.  Installers take a few hours to fill the cavity before they seal up the tiny holes they drilled. They use polystyrene beads that don’t absorb water so there are no damp problems. The insulation retains heat in your home and stop it escaping outside. Therefore, your home will be warm but there will be no change in the appearance of your house and pretty much no hassle.  Just cheaper bills and less gas burnt so lower carbon dioxide emissions. A real win win! It’s easy to check if your house already has wall insulation, you can look around the brick work for signs of circular holes where someone has drilled into the cavity or ask an installer to visit.

Is the Structure of My House Safe with Cavity Wall Insulation?

If you are not sure if your home is suitable for cavity wall insulation, ask a registered installer to come and review your property. Before going ahead with cavity wall insulation, get three written quotes from companies approved by the Cavity Insulation Guarantee Agency. Previously, expanding foam was used for cavity walls but as technology progresses most installers use polystyrene beads. The national cavity wall insulation guarantee provides a 25-year independent assurance on the work on your home when using a registered installer.   

Options for Solid Wall Insulation

Insulation board being fitted in a home

Nearly half of all heat produced in a home escapes through solid walls. Older homes (pre-1920) are likely to be built using a single solid wall of bricks or stone. If your brickwork is a mixture of long and short bricks looking from the outside, then it is likely of solid wall construction.

It is still possible to insulate these walls by adding a layer of insulating material either on the inside or the outside of the house. The choice is very much up to your individual preference and budget.

It may be worth getting the opinion of an RICS surveyor before deciding to invest in solid wall insulation. The cost of a surveyor’s report is not high in comparison with the cost of external or internal insulation and is independent and covered by professional indemnity insurance.

Internal Insulation

Internal insulation entails adding insulation boards or lining to the solid walls, resulting is a slight loss of internal space in each room. Internal insulation is cheaper than external insulation, around £6,000 depending on the size of the property. There may be grants available through Government schemes. Your installer will be able to advise on this.

External Insulation

External insulation adds an extra thermal layer onto the outside wall, which is then finished off with a protective render or cladding. This process is less disruptive and retains the original room sizes. However, it is more expensive due to the materials required and will change the look of your property. If your home is in a listed or conservation area, external solid wall insulation may not be suitable.

The cost will very much depend on the size of the property, but a typical home is around £10,000 (grants may be available through Government schemes) again, your installer will be able to offer advice.

Floor Insulation 

Thermal underlay is effective and cheap

Cat sitting on carpet

If you were planning to lay new flooring or have a particular problem with drafts from ground level, floor insulation is a good idea.

Draughty gaps between floor boards or skirting boards can easily be plugged using filler from DIY stores. For wooden floors, the easiest method is to attach solid insulation boards or rolls of mineral wool between the timber joists from a basement below the room. For many homes this is not possible, as floor boards will need to be lifted. If you use a professional, this could cost around £800, depending on the floor area. It’s much cheaper if you can do it yourself.

Rigid insulation boards can be fitted over concrete floors as well, but doors may need to be adjusted and a damp proof membrane added. 

If all this seems too complex to tackle, then thermal underlay is effective and cheap to lay down under new carpets. You will find a good guide to floor insulation via the Which? website.

Grant Funding for Free Insulation and Boilers

There is a huge need to ensure people are safe and warm in their homes as well as to reduce carbon emissions from heating. There are Government grants available for energy efficiency measures in our homes. The grants are particularly tailored towards those that receive any form of benefits or Government support.  Please do use this financial support as it will save you money and also help save the planet. 

Funding is available under the Energy Company Obligation (ECO) scheme to have your home insulated for free or other energy saving measures.  You could qualify for support through the ECO scheme for a new boiler, if you are in receipt of certain benefits or tax credits.

Further Information and Advice on Insulation and Energy Efficiency Measures

To find out more, Home Energy Scotland is on 0808 808 2282 and if you are in Northern Ireland, you can call Northern Ireland Energy Advice on 0800 1422 865.  They often take down your details and someone with relevant expertise will ring you back depending on your enquiry but they are usually friendly, helpful people. Simple energy advice is the website for UK advice.

There are many great websites such as EST and CSE that describe the best way to fit insulation.

Insulation options and their payback for England, Scotland and Wales from the Energy Saving Trust

These savings are for typical gas-heated homes so if a home is heated by oil or LPG then the savings will be higher.

Loft insulation (0 to 270mm)Detached houseSemi detached houseMid terrace houseDetached bungalow
Fuel bill savings (£/year)£590£355£330£590
Typical installation cost*£630£480£455£640
Carbon dioxide savings (kgCO2/year)1000 kg610 kg560 kg1000 kg
Payback time*1.1 years1.4 years1.4 years1.1 years
Table 1. Savings from loft Insulation (0 to 270 mm) sourced from the EST

*if contracted or much less if DIY.  Figures are based on fuel prices as of October 2022.

Loft insulation top up (120 to 270mm)Detached houseSemi detached houseMid terrace houseDetached bungalow
Fuel bill savings (£/year)£55£35£30£55
Typical installation cost*£480£390£370£480
Carbon dioxide savings (kgCO2/year)95 kg55 kg50 kg95 kg
Payback time 8.7 years11.1 years12.3 years8.7 years
Table 2. Savings from loft Insulation (120 to 270 mm); sourced from the EST

*if contracted or much less if DIY.  Figures are based on fuel prices as of October 2022.

Cavity Wall InsulationDetachedSemi detachedMid terraceBungalowMid-floor Flat
Fuel bill savings (£/year)£690£395£235£310£180
Typical installation cost£1800£1000£580£800£395
Payback time2.6 years2.5 years2.5 years2.6 years2.2 years
Carbon dioxide savings (kgCO2/year)1,200 kg670 kg395 kg530 kg305 kg
Table 3. Savings from cavity wall insulation; figures sourced from the EST

These are estimated figures based on insulating a gas-heated home. The average installed cost is unsubsidised. Figures are based on fuel prices as of October 2022.

Solid Wall InsulationDetachedSemi detachedMid terraceBungalowMid-floor Flat
Fuel bill savings (£/year)£930£540£315£420£240
Carbon dioxide savings (kgCO2/year)1,600 kg910 kg540 kg720 kg410 kg
Installation costs: external wall insulation*No estimatesAround £12,000No estimatesNo estimatesNo estimates
Installation costs: internal wall insulation*No estimatesAround £8,500No estimatesNo estimatesNo estimates
Payback timeNo estimates16 to 22 yearsNo estimatesNo estimatesNo estimates
Table 4. Savings from solid wall insulation; figures sourced from the EST

*Based on a typical 3 bedroom, semi-detached house in Great Britain.  Figures are based on fuel prices as of October 2022. 

Floor InsulationDetachedSemi detachedMid terraceBungalow
Fuel bill savings (£/year)£180£110£75£95
Carbon dioxide savings (kgCO2/year)310 kg190 kg125 kg335 kg
Typical installation costFrom £1,600 to £2,900
Payback time*9 to 16 years15 to 26 years21 to 39 years17 to 31 years
Table 5. Savings from floor insulation; figures sourced from the EST

*If contracted or much less if DIY.  Figures are based on fuel prices as of October 2022.


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