5 things I do every summer that are making parts of my house unbearably hot — experts told me I'd been falling foul of these common mistakes

For much of the year my old house is a chilly place to spend time in, with the ground floor in particular somehow refusing to hold on to heat no matter what the temperatures outside – in fact, I have been known to step out into the garden to warm up a little when working from home.

However, once summer hits, the first floor bedrooms transform into stuffy sauna-like spaces that can, at times, become almost unbearably hot, making getting a good night's sleep nigh on impossible. Despite trying all kinds of ways of keeping a bedroom cool, nothing seems to work.

With more warm weather just around the corner (hopefully), I reached out to the experts for some help in the hope of staying cool in bed – and I was surprised to learn that many of my daily habits, some of which I thought would help keep my house fresh and cool, were actually making things far worse. If, like me, you struggle to keep your house feeling breezy in the heat, here's what they had to say.

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1. Opening up windows in warm weather

I don't know about you, but when temperatures rise inside my house, the first thing I do is fling open the windows, after all we have all come to realise the benefits of burping a house. However, according to all the experts I spoke to, this could actually be making matters worse.

'Many people open windows as soon as it feels warm. However, if the air outside is hotter than the air inside, you are effectively pumping heat into your home,' explains Rich Millard, senior sustainability consultant at Building Energy Experts, who goes on to explain the concept of night purging. 'At night, open all windows to allow the cooler air through. Come morning, close all windows and keep curtains drawn before using fans to move around air within the home.'

Kevin Pennington, owner and MD of Lancashire Air Conditioning, agrees that opening windows at the wrong times of day is a seriously bad idea. 'You are allowing warm air in and this then causes the house to get hotter than it would if you kept the windows and doors shut. This applies whenever the outside temperature is warmer than the inside.

'Generally, on days above 25°C that are very sunny, I keep my windows open very early in the morning when the air temperature is still cold and then I reopen them late at night when the air temperature is below that inside,' adds Kevin. 'This is a free, natural way to cool a house.'

Richard Millard

Richard Millard is a Senior Sustainability Consultant with extensive experience in sustainable energy solutions for the built environment. With a First-Class Honours degree in Architectural Engineering, Richard is particularly adept at low-energy building design for both new constructions and retrofits.

Kevin Pennington

Kevin is owner and managing director of Lancashire Air Conditioning. He specialises in domestic AC installations in England and has installed over 1000 AC units and managed many more. Kevin has an encyclopedic knowledge of UK-stocked AC units designed for homes and is a member of the Institute of Refrigeration, holding the designation TMInstR.

2. Leaving my appliances on

I'm going to admit that I am terrible when it comes to turning anything off at the sockets – appliances, chargers, lamps, you name it, there they sit on stand-by. Not only do these vampire appliances guzzle energy, but, according the the experts, they could also be making my house hotter.

'We often forget that appliances (ovens, computers and even big-screen TVs) act as radiators,' points out Rich Millard. 'Leaving these on standby or cooking heavy meals during the hottest part of the day significantly raises the baseline temperature.'

'Other appliances that cause excess heat are dishwashers and tumble dryers,' picks up Kevin Pennington. 'In a hot spell, the heat produced by these appliances can take rooms from being hot to being unbearable. And on a hot day it is far better to dry clothes outside than in the tumble dryer anyway – it’s free, better for the environment and, in my opinion, the clothes feel better (fluffy towels excluded).'

3. Not being tactical about closing my curtains

On a hot day, I always mean (but often forget) to nip upstairs in the afternoon to close the curtains in our south-facing bedroom – it makes the world of difference to how cool the room feels come bedtime, keeping it closer to the ideal temperature to sleep in.

'Homeowners often leave curtains and blinds open to enjoy the natural light in south-facing rooms but this creates a greenhouse effect that is very difficult to reverse once the sun goes down,' explains Rich Millard. 'Rather than just closing thin indoor curtains though, use heavy, light-coloured curtains or, ideally, external shutters or awnings too.'

I hadn't actually realised the effect using the right types of bedroom curtains could help here.

'Heavy materials in dark fabrics, and aluminium or dark wood blinds, absorb heat,' explains Kevin Pennington. 'This causes the room to get significantly hotter than it should be. A great way around this is getting white or light-coloured curtains and fitting them as close to the glass as you can to reflect the light away. Heat reflective film on the windows and their reveals really helps too.'

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4. Not addressing my lack of adequate loft insulation

While this one is going to take a bit more effort to put right than some of the others, I am horribly aware that one of the main reasons my house gets too hot upstairs is because of the lack of proper loft insulation.

'There is a common myth that insulation is only for keeping heat in during winter. In reality, poor or patchy insulation allows external heat to seep through the roof and walls more quickly in the summer,' explains Rich Millard.

'An uninsulated loft with dark tiles or slates is effectively a large heater,' picks up Kevin Pennington. 'The tiles or slates get red hot during the day leading to an air temperature in the loft of up to 50°C in some circumstances. If there is no insulation between the loft and the house then the heat in the ceiling above the rooms can becoming incredibly warm.'

5. Using my air conditioning all wrong

Whenever a heatwave hits, you can pretty much guarantee that there will be a rush on portable air conditioners, and for good reason. I recently got my hands on this Vonhaus' portable air conditioner and it really does make a difference so quickly, but, only now am I realising that I could be using it so much more effectively.

'The mistake I see all the time is people trying to cool the room they’re in, while leaving warm air to drift in from the rest of the house,' explains Tom Houlker, air conditioning installation and service expert and the director of Houlk Air. 'Cool air escapes quickly through open internal doors, stairwells and unused rooms, so the AC ends up chasing heat rather than controlling the space.'

So how should I use it? 'Treat it like zoning, shut off the areas you’re not using, keep airflow clear around the unit, and let it cool one space properly instead of asking it to fight the whole house,' advises Tom.

Tom Houlker

Tom Houlker is the director of Houlk Air, heating and cooling specialists, based in Manchester. Tom has over 10 years of experience working in the HVAC industry and has risen from a building services engineer to the director of his own air conditioning company. He is an expert in air conditioning, cooling, and heating and can provide expert comments on all aspects of the industry as someone who has worked at each level.

FAQs

Can using a fan cool down a room?

The best fans can definitely provide some relief during hot spells, but it is important to realise their limitations, as well as the most common fan mistakes, if you want to get the most out of your particular unit.

'Don't just point a fan at yourself. Use fans to move air within the home to prevent hot spots, or place a fan near a window at night to help pull the cooler outside air in more efficiently,' advises Rich Millard.

Some people swear by placing a bowl of ice behind the fan in order to cool the air being blown out – I actually tried this and found it surprisingly effective.

While fans can provide a very welcome breeze in warmer weather, it is important that you understand where not to put a fan if you want to feel maximum benefits.