How to keep a house cool in summer: with or without AC

Coping with extreme heat in a home is not easy and when high temperatures come about, knowing how to keep a house cool in the summer is a must. Act fast for a more comfortable space and to prepare for future heatwaves

Front porch with light wood deck, small planters and white deck railing on modern home
(Image credit: Getty Images)

Knowing how to keep a house cool in summer is becoming more and more important. With climate change having an increasingly negative effect all over the world, one way that you may be directly feeling the impact is when your home drastically overheats, as temperatures unexpectedly soar. Whether you live in a warmer climate but have noticed a more intense heat of late or if you're based in the UK, where even warm summers used to be a rarity but, where they are now dealing with extreme and unprecedented heatwaves, you'll want to know not only how to cool down your house quickly but, with an unclear future for the ongoing effects of climate change, it is well worth exploring more long term options to protect your home and all its residents from extreme heat also.

Bringing down the temperature of an entire house is in many ways similar to cooling individual rooms down, like your bedroom. However, when you have more than one floor, you may be struggling to regulate the temperature of your entire house, and if you live in a usually cooler climate, your home naturally won't be designed to deal with the heat, compared to say if you had a home in the south of France, as your home's layout likely doesn't leave room for much airflow, while even the choice of floor covering could be a contributing factor to why you're struggling to keep your space cool.

Quick ways to cool down an entire house in summer

First things first, before you start opening all of the windows, you need to check the temperature outside vs. inside. If you have a smart home thermostat this should tell you the inside temperature of your home – the optimal temperature sitting around  70 to 78 F/25.56 C – and if it's predicted or already warmer outside, you'll want to keep windows closed.

1. Make fans work double

If you have AC installed, you're starting off strong, but if you live in the UK it's unlikely and you'll have to pay out for a retrofit if you do want it in the future. So, if you like many are reliant on fans for any sort of breeze – because we know they don't dish out cold air much to our dismay –, when a heatwave comes about you'll need to really make the most of yours.

Even if you have one of the best fans out there, it's probably worth getting a couple more to cover a bigger square footage and that way you can try different ways of getting your fan to blow cold air also. One hot tip is to keep one on the floor so that it pushes cooler air around your home, with another towards an open window (temperature allowing) to push warmer air out.

2. Open windows only when it's cooler

When the air is cooler, open the windows on all floors to increase ventilation and airflow. The very early hours of the morning will be the best time to do this in a heatwave. 

Phil Steele, future technologies evangelist at Octopus Energy (opens in new tab) notes 'While the air is warm outside, try not to let it into your house. Ventilating your house by opening windows and throwing open curtains while it's warmer outside will just make your room the same temperature.'

Sahar Saffari, an interior designer at Hi-Spec Design (opens in new tab) also counts tactical window opening as an effective quick solution to cooling a house in summer 'our first instinct is to let in the fresh air and open the windows, but if it’s hotter outside than your home then do not have the windows open all day. The best idea is to open the windows early in the morning and in the evening, this way when it cools down you can let the fresh air in, but keep the hot air outside during the day.'

White curtains billowing in breeze of blue kid's room

(Image credit: IKEA)

3. Open doors tactfully 

In the same breath, Saffari notes to keep patio doors shut 'This is the same for your doors, if your house is cool, keep the hot air out!' 

Meanwhile, if you don't live in an open plan space, do keep internal doors open to increase airflow around the home generally, especially when you are able to open windows for ventilation.

If you have a conservatory or glazed room, you may want to consider closing the connecting door to your home as it will get hot and the heat will transfer. 

In glazed spaces, ensure any blinds are closed where possible and consider a portable air conditioning unit. Keep children, elderly people and pets out of these areas also as they are more likely to overheat due to the nature of their design.

4. Close all window coverings

Whether you have blinds, curtains or shutters, keep them closed in the day to not let excess heat in from the sun's rays. Saffari adds 'this may seem obvious, but it’s something many people forget when it’s a beautiful sunny day outside. Your first thought might be to let the sunlight in, but light equals heat, which is a sure way to heat up your home quickly. So, if you want to sit in the sun, then do that whilst you’re outside and keep your home shaded.'

5. Be wise with how you use your AC

First thing's first, you'll be surprised just how many of us have our heating on without noticing. So double-check that it's not running, even for just an hour or two in the background as this will obviously help keep the temperature down indoors, and save you money also.

You then simply need to be clever about how you use your AC if you are fortunate enough to have it installed. A study (opens in new tab) of heat pump operation in British Columbia, Canada (a heat pump is like an air conditioner but it can also provide heating) actually found that many participants are using heat pumps to cool the interior when outdoor temperatures are below typical interior temperatures.

'Why would someone be using AC when it's colder outdoors than inside? It's likely because they want to cool down the house before going to bed, and their insulated home is still retaining heat from the warmer part of the day,' says Allan Lake, Founder of Good Guys Heating, Cooling and Plumbing. 'Being aware of the situation and opening windows beforehand could reduce or eliminate the need for AC.'

6. Reduce use of large appliances

Not that a four-course meal will tempt you when it's extremely warm but reconsider using your oven so much and even other appliances like your microwave, dishwasher and washing machine as they all generate heat. If it's a must, choose lower cycles/use time where you can and try to use them at times where it is cooler outside so that you are able to let some of the heat escape through the windows.

Ambient kitchen with

(Image credit: Cafe Latte)

7. Swap out old bulbs

Simply switching the lights off can help make a space feel cooler but using more energy-efficient bulbs (opens in new tab) can significantly reduce heat fast also as old bulbs give off 90 per cent of their energy as heat compared to 10 per cent by LEDs, that also last 25x longer. So for the rooms where you want the lights on in the evening consider swapping out old bulbs for near-instant relief energy-saving options.

8. Add shade where possible

If you have outdoor space, you could consider quick to install sunlight blockers in the form of tall garden plants or even garden screening to dampen the sun's rays on your property, 'light equals heat, so being able to keep your house in the shade is an ideal way to keep it cool.' Says Saffari. 'If you have a garden, can you plant a bush that shades some of the windows? Or, if you have a balcony can you shelter this with bamboo? Of course, you still want to allow sunlight into your home throughout the cooler months, but adding a little extra shade to help in the summer is a natural and economical way to prepare your home for the hot weather.'

Long-term solutions to keep a house cool in extreme heat

A multi-layered approach always works best and while short-term solutions are a necessity for lots of us, with the current state of climate change it makes sense to set foundations in place to help ease the effects of climate change and rising global temperatures on your home in the future.

'As global warming continues to impact the weather, homeowners are becoming increasingly aware of the need to take taking  proactive steps towards controlling and managing temperature in their homes.' Says John-Paul Manning, MD at Insulation4Less (opens in new tab). 'The temperature of our homes can have a significant impact, not only on the quality of our property, but on our quality of life as well.'

Manning notes how 'Small changes such as painting our interiors or swapping out traditional bulbs for more eco-friendly are becoming increasingly more popular, but we are definitely seeing an increase in more permanent home renovations such as adding solar reflective paint to exterior walls and installing energy efficient windows.'

Saffari recommends a combination of temporary and more longer-term design solutions also.

1. Install thermal blinds

The sun provides valuable extra warmth for most of the year, but in a heatwave, it can serve to provide extra heat to rooms, particularly on the southern elevations of homes. 

The simplest solution for bedrooms and loft conversions is to look at so-called thermal blinds which tend to have an aluminum-lined honeycomb construction designed to reflect up to 85 per cent of the sun’s heat. Try the DuoShade from Blinds2Go (opens in new tab) – they have the added benefit of keeping the light out on those early summer sunrises. 

These will be even more effective if you have blackout curtains or blinds; they aren't expensive, Invest now so you are sorted for the rest of the summer.

Velux external anti-heat blinds in loft kitchen with bench seating

(Image credit: Velux)

2. Consider anti-heat external blinds

Most of us know about the types of blind that fit on the inside of our interiors – but do you know that you can cool down a home by using external blinds on different rooms. VELUX anti-heat blinds (opens in new tab) reduce passive heating on the outside of your home and maintain a cool, comfortable temperature in the said room without compromising on your outdoor views or natural lighting.

Editor in chief of ecommerce, Lindsey Davis swears by these in her home, explaining: 'My loft has two south-west facing windows so it gets unbearably hot. Blackout blinds were not making enough difference – I had resorted to putting aluminum foil in front of them to reflect the sun,'

'The key was stopping the sun getting through the windows in the first place. These external blinds do just that and have reduced the heat in my loft bedroom by a couple of degrees. Not much, but enough to make the difference between being able to sleep or not.'

3. Check your home's insulation

Home insulation is often overlooked in warmer months when it actually plays a major part in regulating the temperature of your home and without it, you could be spending too much on both heating and cooling your home. If you have no damp issues and a loft/attic that is easy to access, you can actually insulate it yourself and save a ton of cash in the process.

For homes in warmer climates, the Department of Energy (opens in new tab) advises installing a radiant barrier to reduce the likelihood of your home overheating in summer and to cut your AC costs altogether so it's worth exploring.

A bright living room with home office area and ceiling fan

(Image credit: YinYang / Getty)

4. Install ceiling fans

Rotating ceiling fans can provide instant relief in hot weather and are a more economic option compared with the cost of installing AC according to Saffari. 'These are more economical than AC units, so can save money and energy over time. However, make sure you consider the size and height of the room when shopping for your fan and if possible, listen to how loud the fan is before having it installed.'

5. Decorate with cooling in mind

Although these can be quick changes to make, the benefits won't necessarily pay off overnight so it's worth considering them in general for when you next go to redesign your living or bedroom. 

Much like when dressing for warm weather, choosing light-colored and breathable materials will help keep you cool. Saffari adds 'when decorating your home, think about the types of materials you are using for your soft furnishings, and not just your bed and bedding. For example, steer clear of a leather sofa or fluffy cushions. Some examples of alternative and breathable materials are cotton, linen and silk.

'Dark colours absorb heat, so decorate your home with lighter colours. These lighter colours will also add an airy feel to your space, which will help if you’re having to keep the light out of the room on a really hot day.'

Saffari also notes that some indoor plants over time could help cool a home. 'Another natural way to keep your house cool is to invest in some house plants. Plants not only absorb heat, but some can also increase the air quality in a home so will improve the overall breathability of the home on a hot day. Although this isn’t likely to make an instant difference, it will help in the long run. Some examples of plants that increase air quality are rubber plants, peace lily, Dracaena.'

A modern traditional living room with white upholstered sofa, small nest tables in center of room, jute rug, white floor rug and chandelier lighting decor

(Image credit: Ikea)

6. Paint your roof and exterior surfaces

Pictured on dreamy postcard landscapes and in holiday brochures, the idyllic islands of Greece are often chock-full of blue and white painted buildings. And there's a good reason for it.

Other than looking aesthetically appealing, painting rooftops, external cladding and bricks this color can help to bring the temperature in your home down. According to former UN secretary general, Ban Ki-Moon (opens in new tab), white paint 'can reduce the temperature of the roof by 30 degrees [Celsius]...this can have a tremendous, significant impact.'

'Depending on the setting, cool roofs can help keep indoor temperatures lower by 2C to 5C as compared to traditional roofs.' says Anjali Jaiswal, of the US-based Natural Resources Defence Council in the same BBC World news report (opens in new tab).

It doesn't have to be brilliant white, so why not take a look at the best white paints for a more exciting take on emulsion?

7. Upgrade to double-pane glass windows

The cost of double pane windows is worth it in all seasons. 'Windows can play an important role in helping to regulate temperatures in our home,' says John-Paul Manning, MD at Insulation4Less (opens in new tab).

'But it's not just how often we keep them open and closed, but also in terms of how energy efficient they are. They absorb a significant amount of ambient heat from the sun, especially if it shines directly on the glass, which can make your interiors extremely hot.'

'As a result, a good tactic is to replace old windows with more energy-efficient options. Dual-pane glass insulates almost twice as well as single-pane, while triple-pane glass maximizes your energy efficiency by reducing thermal transfer. Like most temperature control renovations, this can also help in the winter months, so it’s definitely a worthy investment.'

8. Explore UV deflecting options

Saffari also notes the benefits of UV deflecting glass: 'UV-deflecting windows or window film is an extremely effective way of keeping heat out of the property, without having to have the blinds shut all day. So, this is a great long-term solution for keeping the heat out. However, it does not block all the heat, only an excessive amount so can help the property stay at a comfortable temperature.'

Orange and white straight tiles across open plan kitchen and dining room space with retro bright features

(Image credit: Fireclay Tile x Danielle Nagel)

9.  Rethink your flooring

In warmer climates, houses tend to be (beautifully) tiled so if you're not keen on your carpet anyhow it could be worth considering alternative types of flooring.

Saffari notes how 'carpets store heat, so remove these if you can. Opt stone, porcelain or ceramic flooring instead. You can also have rugs around the property for when it’s not as warm, but these should be removed when the weather starts to heat up. Again, if you are looking for a permanent option you could invest in underfloor cooling. It’s a brilliant alternative to air conditioning and a great way to cool down.'

10. Favor an open plan configuration

As mentioned, a home designed for better air movement will help keep your property cool and those with open plan layouts will note a far loftier and breathable feel to their space, even in extreme heat so it's worth considering this design feature should you be looking to move home in the future or remodel a house yourself. 

'If you are moving into a property, or designing a property then think about the layout. Keeping a property open plan will help with the overall ventilation of the space. This type of layout will also allow for a spacious atmosphere on days when the heat can make you feel claustrophobic. However, this only works if you are following the other advice, such as keeping the sunlight out.' Adds Saffari.

Camille Dubuis-Welch
Camille Dubuis-Welch

Camille is Deputy Editor of Realhomes.com and joined in January 2020. Her love of interior design stemmed from a childhood spent dreaming up weird and wonderful ways to renovate her grandma’s house in France – a greenhouse roof was involved – and it was spending time around very good-looking house plants and in a hardworking kitchen garden that gave her a green thumb. When Camille isn’t sipping coffee and/or writing, she is seeking out cool new Facebook Marketplace finds or tapping into her other creative outlets: painting and clay throwing. She currently rents in North London with her French cat and two others, and hopes to one day renovate the most sustainable house of dreams, somewhere marvellously sunny with a wild, lavish garden and chickens, of course.

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