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How does insulation work in the summer?

Insulation is often thought of as a way to keep your home warm in the winter. This is, of course, true – but what often gets forgotten is that it can also benefit you in the summer.

How does insulation work?

Insulation works by slowing heat movement between two materials. It uses dead air space or cells within a material to trap air and slow heat flow between objects of differing temperatures. If you have uninsulated walls, heat travels through them easily. This means on a cold day, you may notice your heating disappearing. It works in the opposite way too – on a hot day, it can be hard to keep cool air in and warm air out.

How does insulation help in the summer?

Our external wall insulation helps stop the passage of heat by trapping air bubbles within the insulating material. This means it’s easier to maintain a comfortable temperature in your home. A good demonstration of this is loft insulation. If you have your loft insulated at joist-level, you will probably have noticed that it gets very cold up there in the winter. This is because the insulation is stopping the heating in your home escaping up into the loft, where it would be wasted. On the other hand, if you go up there in the summer, you’ll notice it’s hot in the loft space, because hot air is coming through the roof but not getting into the main body of your home.

Although any insulation helps reduce air transfer, external wall insulation is the best type. It stops up to 40% of heat transfer through walls – which can make a big difference. Our expanded polystyrene (EPS) boards for external insulation are made up of 98% air. This is good news because air is the best insulator there is when it is trapped and unable to move around. It creates a barrier which is very difficult for hot or cold air to get through.

On hot days, insulation prevents your home from overheating because if your walls are heated by sunlight, the heat doesn’t pass through to the inside of your home. If you have an air conditioning system, adding a layer of external wall insulation can make it more effective. If you don’t, you can still reach a comfortable temperature by opening the windows to let in cool air at night and closing them during the day. External wall insulation will help keep this cool air inside.

Why install external wall insulation?

Reduce the need for air conditioning in the summer, save money on your heating bills in the winter, and feel more comfortable all year round. External wall insulation has other benefits too – it helps you to reduce your carbon footprint because you’ll need less heating, it reduces noise entering your home, and smartens up the outside of your home.


7 thoughts on “How does insulation work in the summer?

  1. We had our home insulated last winter when they filled the cavity walls. We have noticed a huge difference this summer when even on the hottest days the insulation has stopped our home getting too hot I guess by slowing movement of heat into the home.

  2. I thought insulation would look the heat in the house like it does in the winter! A useful blog as never thought of it like that!

  3. My house gets so hot in the summer because of solar gain and the insulation we have applied to the outside of the house then doesn’t let the house get cool again. I am looking for a solution to lower the level of solar gain – is there a film I could put on the windows? I have read growing a tree in front of the window is the easiest option but I love our view!!

    1. Hello Kevin79,
      There are many differing types of structures, so things can vary from project to project. If it’s a lightweight structure or has lots of glazing, it is easy for summertime overheating to occur. It sounds like you need add mass, which could be done with wood fibre insulation for example, as the suns energy is often greater than the performance of the building. (Like planting a tree, without losing the view).
      Not sure if you are planning any more work to the house, but if so give us a call and we can advise.

  4. Insulation definitely works in the summer. We had our loft done and it doesn’t matter what time of year it is, the rooms up there sit at a constant temperature. Definitely worth doing!

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