Why you should think about insulation all year round

As we make our way into summer, insulation is probably the last thing on your mind. However, insulation isn't just designed to retain heat – it also keeps it out, which will help you stay cool during hot summer days.

With the cost of bills continuing to increase, it's likely you're looking for ways to cut your spending. Properly insulating your home will keep your energy bills down during winter, plus it keeps your home cool during a hot summer. 

Read on for a closer look at the benefits of insulation. Plus, find expert tips on how to prepare your home for winter.

To find out how your own home could save money and become more energy efficient, try out our home energy planning tool

How insulation works during summer

The UK is heating up. According to the UK State of the Climate report (published in July 2024), recent decades have been warmer, wetter and sunnier than those through the 20th century. In fact, the report also finds that 2023 was the second warmest year on record for the UK since 1884. 2022 was the warmest. 

Typically, a British summer doesn't last very long, which is why most of us don't have a home-wide air conditioning system. 

Plugging in a fan usually stored away in your cupboard will provide some relief, but their powers are limited. 

You can also buy portable air conditioners to keep your home cooler. However, they are expensive, tricky to store in between summers if you don't have much space, and use a lot of energy – helping neither the environment nor your bank balance. 

See more: head to our guides to the best fans and best portable air conditioners

While insulation doesn't change the temperature of air (in either winter or summer), it does prevent or slow down the movement of hot air into colder places. In winter this means keeping the air you've warmed up inside your home. But on a hot summer's day, when your home is cooler inside than the air temperature outside, good insulation limits the amount of heat that can travel through the walls and roof, meaning your home stays cooler for longer. 

Other tricks like keeping curtains and shutters closed to avoid air being heated by direct sunlight will help your insulation work most effectively.

Get started: how to insulate your home

Loft insulation to keep cool

Loft insulation is a relatively cheap and effective way to keep the heat out - or in. The Energy Saving Trust estimates that a quarter of heat lost from an uninsulated home escapes through the roof. It adds that, when installed correctly, loft insulation 'should pay for itself many times over in its 40-year lifetime.'

In many cases, you should be able to install loft insulation yourself. You can buy rolls of insulation online or from homeware stores. Lay it between the joists making up the floor of your loft. Add a second layer at right angles to achieve the minimum recommended depth of 270mm.

See more on types of loft insulation and how to buy insulation boards

If you want to lay boards on top of the insulation to be able to use the space for storage, make sure you use spacers to hold the boards up and ensure that the insulation is not being squashed down, as this reduces its effectiveness.

Installing insulation at floor level in your loft means the roof space above will still get hot in summer (and will be cold in winter). If you plan to spend time in your loft space, or store temperature-sensitive items there, insulating at rafter level - the underside of the roof, as in the photo above - may be a better choice. It's more expensive and usually needs professional installation, but your loft itself will then stay cooler in summer and warmer in winter.

For more details on loft insulation and how much you can expect to spend, see our guide on loft insulation costs and savings.

Use the summer to prepare your home for winter

You can also make the most of the spring and summer months to tick off the DIY jobs that will help you save money during winter.

Make sure that your insulation is up to scratch, and take the time to seal any draughtproofing issues. 

For ideas about small, cheap improvements to your insulation, read our guide on how to draughtproof your home.

We also recommend getting your boiler serviced during the summer. Towards the end of the year, boiler professionals are in high demand. Getting a service over summer can identify any faults early so that you can make repairs in good time and avoid an emergency call-out when the weather is cold. 

See our guide on getting the best boiler service for more details.

Other summer jobs to consider include:

• Clearing your gutters: remove winter debris from your gutters to prevent water from pooling and causing damp patches or leaks
• Checking your roof tiles: tiles can loosen during winter storms, so it's worth having a look to see if any slates need replacing. Note that a build-up of moss can obstruct drainage points, too
• Bleeding your radiators: It's a good idea to do this at least once a year so you're getting the most out of your heating. If your radiators are warm at the base but cooler at the top, this is a sure sign they need bleeding. Check out our guide to bleeding your radiators.
• Investigating any damp patches on walls and ceilings: our guide can help you identify problems and solve them before major structure damage occur: what kind of damp is affecting my home?

Contacting a Which? Trusted Trader

If you need professional help insulating your home, we recommend using a Which? Trusted Trader.

The Which? Trusted Traders scheme recognises reputable traders who pass a strict assessment process. Before a trader can earn their 'Trusted Trader' title, we check the trader's credit reports, customer satisfaction and business procedures, as well as conduct an interview and assessment.

You can use our tool to find a reliable local trader: