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Home & garden.

29 September 2021

How to make your home more energy efficient

From home energy audits to low-energy lightbulbs, an efficient home means lower energy bills - find out where to start
KL
Karen Lawrence
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Many of the UK's homes are inefficient to heat, leading to high energy bills and a big carbon footprint.

Our housing is some of the oldest and worst insulated in Europe. According to Energy Performance Certificate (EPC) data, only a third of owner-occupied homes achieve the most efficient A-C ratings.

The government is encouraging homeowners to improve their EPC rating to band C by 2035, claiming that more than half of homes currently in EPC bands D-G could achieve that.

But it's not just about following government advice or saving the planet – the most obvious reason to improve your home's efficiency is that you'll see an immediate decrease in your energy bills. 

How energy efficient is your home?

The first step is to find out how much energy your home uses, and how to improve it most cost effectively. 

If your home has an Energy Performance Certificate, it will help you identify possible improvements. Your property is likely to have an EPC if it has been marketed for sale or rent since 2008. 


Find your EPC

You can find any current or expired EPC for a home in England, Wales, or Northern Ireland on the government’s EPC Register or, in Scotland, on the Scottish EPC Register run by the Energy Saving Trust. You can also find a list of qualified Domestic Energy Assessors on either website.


EPCs are valid for ten years, so it may have expired and, if you have made changes to your home since the date of the EPC assessment, it may no longer be accurate.

If your home doesn’t have an up-to-date EPC, you can get one for around £60-£120 depending on the size and location of your home. 

For a more detailed report, look for assessors who offer a home energy audit. Although more expensive, it may include thermal imaging as well as one-to-one advice and a comprehensive plan to help you upgrade your home.

What information is on an EPC?

The EPC shows the current and potential energy efficiency rating of your home from A (most efficient) to G (least efficient). It also lists ways you can improve the rating along with indicative costs. The government-endorsed Simple Energy Advice website has more information about what you can learn from your EPC.

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The recommended improvements may include big projects like installing external wall insulation or solar panels, as well as smaller changes such as switching to low-energy lighting. The EPC lists the recommendations in the order that they should be carried out to maximise their effectiveness.


Home energy audit checklist

If you don't have an EPC, or other professional assessment, you can try doing a basic DIY home energy audit. Walk round each room in turn and note down what you find.

  • Insulation: Inspect the loft, external walls and ground floor, if accessible. Look for insulation around the hot water tank and pipes.
  • Draught proofing: Check around doors, windows and other openings for draughts and gaps. Don't forget the loft hatch, letter box and keyholes.
  • Heating: Make sure your boiler, radiators or other heat sources are working efficiently, and check that heating controls, timers and thermostats are set correctly. 
  • Lighting: Check that all lighting is fitted with efficient LED bulbs, including in ovens, extractor hoods, and external lights. 

Armed with your energy efficiency information, you can start planning what action to take.

Cutting energy use: the 'fabric first' principle

The warmth created by your heating system – and the energy used – will be quickly lost through any uninsulated areas. Tackling these first will make your home noticeably warmer, lower your bills and improve your EPC score. 

Making improvements to the fabric of your home – that is the walls, floors, roof and windows – is widely acknowledged to be the best place to start if you are trying to reduce your energy use. 

Here are the main ways you can make improvements:

1. Add wall insulation

Uninsulated homes lose more than a third of their heat through the walls. A detached house loses heat through the walls on every side, as they are all exposed to the outside air, whereas a mid-terraced house or flat has fewer external walls so experiences less heat loss. 

Check what type of walls you have. You need to know how your walls are built because the methods of insulating each type are quite different. The age of your home can give you an idea of the type of wall construction.

  • Most homes more than 100 years old have solid walls, usually brick or stone. Internal and external solid wall insulation systems are available.
  • Homes built after 1920 are likely to have cavity walls, comprised of two walls with an air gap (the cavity) in between. Insulation can usually be installed in cavities no less than 50mm wide.
  • Modern homes built after 1990 normally have insulated cavity walls, and shouldn't need to be upgraded.

Read more about solid wall insulation and cavity wall insulation installation, including costs and savings.

If your home has a steel or timber frame, or is a pre-fabricated concrete construction, you may need advice from a specialist insulation installer.

2. Add floor insulation

Up to 15% of lost heat goes through the ground floor of your home, so it should be insulated if possible. It's not normally needed for upper floors, but if you have a room above an unheated space, such as a garage, insulation may be beneficial.

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Check what type of floors you have. Like walls, you need to know what type of floors you have to choose the right sort of insulation.

  • Suspended floors, usually floorboards, rest on joists above a void space. They can be insulated using rigid boards, mineral wool, or spray foam insulation.
  • Solid floors are generally stone or concrete. A layer of rigid insulation can be laid on top.

Many homes have both types of floor so you may need more than one approach. 

Find out what type of floor insulation is best for you.

3. Add roof and loft insulation

Insulating a roof or loft is one of the most cost-effective ways to improve your home's energy efficiency. Large detached houses and bungalows lose a large proportion of their heat through the roof, but most homes can benefit from a minimum of 270mm of loft insulation. 

What type of roof do you have? Most roofs can be insulated, but there are different methods.

  • Pitched roofs can be insulated at joist level as a cold roof, often called loft insulation, or at rafter level as a warm roof. Insulation rolls, rigid boards, and spray foam applications are all available.
  • Flat roofs can be insulated as a warm deck, cold deck, or inverted roof.

Learn more about roof insulation and the costs and savings of installing loft insulation.

4. Upgrade windows and doors

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If you have single-glazing, replacing it with more energy-efficient windows will make your home warmer and quieter. Not every home can install replacement windows, but there are other options.

  • Double glazing is the most common type, made up of two panes of glass with a sealed gap between, filled with air or an inert gas. 
  • Triple glazing is made up of three panes of glass with two gaps, and can be more effective than double glazing.
  • Secondary glazing is not a replacement, but is added to existing windows to improve heat retention. It can be a good choice for rented properties, listed buildings and homes in conservation areas where replacing the windows is not permitted.

Find out how to choose the best type of double-glazed windows and doors for your home.

5. Add hot water cylinder and pipe insulation

Your boiler works hard to heat water for taps and radiators, but a lot of that heat can be lost through an uninsulated water tank and distribution pipes. Insulating your hot water tank alone is likely to pay for itself in just one year and is very easy to do.

  • Fit a cylinder jacket. They are cheap to buy and easy to fit, but make sure it’s at least 80mm (3 inches) thick.
  • Insulate all accessible hot water pipes using off-the-shelf foam tube. 
  • Add reflective panels behind radiators to prevent heat from being lost through external walls. They are especially effective for radiators on uninsulated solid walls.

6. Draught proofing

Although controlled ventilation is important to prevent damp and condensation, uncontrolled draughts waste heat and energy. DIY draught proofing is easy using off-the-shelf products to seal around doors and windows, and ready-made products are also available to draught proof keyholes and letterboxes.

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Read more about how to draught proof your home.

7. Energy efficient lighting

Although lighting may seem a minor part of your home's energy use, it is part of the EPC assessment. Swapping old light bulbs for low-energy LEDs can even improve your EPC rating.

LED bulbs are more expensive to buy, but they use around 90% less energy and can last up to fifteen times as long. 

Read all about LED lights and discover our best buy light bulbs

8. Use low-carbon heating

A whole new heating system isn't possible for everyone, so it's worth getting through the points above this one before you consider an upgrade. 

But if your home is very well insulated, and if you're in a position to do so, it's time to think about the way it is heated.

A well-insulated home will have a lower heat demand than a poorly insulated one. When you replace or upgrade your heating system, it should be sized to suit that reduced heat demand. A system with a lower heat output is likely to cost less to buy and install and the ongoing running costs – your energy bills – will also be lower. 

A good heating engineer should be able to calculate the right size boiler to meet your hot water and heating needs. 

Check Which? Trusted Traders to find your local heating engineers.

Energy-efficient fossil-fuel heating

Although gas and oil boilers will be phased out in due course, they may still be the best choice for you right now. To keep carbon emissions as low as possible, find out which boilers are the most efficient and find out how to use heating controls and thermostats most effectively.

Switching to a low-carbon system

Over the coming decade or so, new types of heating system are likely to become available. Alongside ground and air source heat pumps, we can expect to see other technologies that use electricity to generate heat. 

This is an increasingly low-carbon energy source as more electricity is generated by renewable sources like wind and solar. 

If you're interested in solar 

Read our overview of the different types of heating system currently available to find the best heating for your home.