With temperatures rising and UK summers becoming hotter, many flat dwellers are finding themselves uncomfortably warm – especially in built-up urban areas where heat lingers well into the night.
The London Homebuilding & Renovating Show (19-21 September, ExCeL London) brings together leading eco, property, and interiors experts who share practical, proven ways to keep homes cooler, from innovative shading to water-based AC systems.
Here’s what they have to say:
Paul Testa, sustainability expert for the London Homebuilding & Renovating Show:
Struggling with the heat in your flat?
Block out the sun
The most effective way to stop your home from heating up is to keep direct sunlight off your windows, especially those facing south and west.
- If you have permanent external shading, fantastic!
- If you’ve got blinds, curtains, or temporary shades, use them during the day—especially when the sun is strongest.
- Keep in mind the sun moves! Adjust which windows are covered as it travels across the sky.
Got roof windows or skylights? Don’t forget those! Close any blinds if the sun hits them directly. If you have a flat roof that’s safe to access, consider placing a light-coloured sheet over external roof windows to reflect sunlight (only if it’s safe to do so!).
Let in the cool night air
As the sun goes down and temperatures drop (usually in the evening, overnight, and early morning), open your windows wide to let the cooler outside air flow in.
- Make sure it’s safe to do so before leaving windows open at night.
- East and north-facing windows are usually coolest earliest, so start there.
Seal it up during the day
By about 8am, once it starts heating up outside, close all your windows and curtains. It might feel wrong, but this traps the cool air in and keeps the hot air out. Just like you don’t leave a fridge open if you want it to stay cool, you need to keep the hotter external air out of your home.
Repeat daily!
Following this routine can make a big difference – your home could stay up to 10°C cooler than the outside temperature during the hottest part of the day.
The biggest challenge with the above is if overnight temperatures or noise/pollution makes night time purge more difficult. Then, no matter what else you do, heat will build up over successive days of high temperatures.
Also consider changing other bits about routines:
Cook with ovens less, cook quick things on the hob or in the microwave/air fryer, or even use the BBQ more to emit this heat outside rather than inside.
Michael Holmes, property expert for the London Homebuilding & Renovating Show:
Air conditioning (AC) in flats can be quite challenging, particularly in mansion blocks where managing agents typically prohibit external ducting, pipework, or AC units mounted on walls or roofs. This issue is further complicated if the building is listed or located in a conservation area, where additional permissions are required.
In these cases, the only viable solution is a water-based system. This system extracts heat from the air and transfers it to cold mains water, which is then discharged into the wastewater system and ultimately into the sewer network.
However, it’s important to note that freeholders and managing agents may still need to approve the volume of water consumed and the increased drainage capacity before installation. Additionally, if the building is listed, internal alterations will require consent. Despite these considerations, a water-based AC system offers a viable option that avoids any external modifications or alterations.
Julia Kendell, interior design expert for the London Homebuilding & Renovating Show:
One of the most effective solutions is to mitigate a build-up of heat during the hottest hours of the day by closing thermal blinds (which reflect heat in the summer and keep warmth in during the winter).
External shutters, a pre-requisite in Mediterranean climes, are a worthwhile investment as temperatures rise.
Keeping a collection of houseplants will also help to lower indoor temperatures. When plants ’transpire,’ the surrounding air is cooled.
Darker colours absorb light so for rooms that are south-facing, a cooler, lighter colour palette is a good choice.
David Hilton, eco expert for the London Homebuilding & Renovating Show:
Flats are difficult, especially in built up areas. Very often there is a lot of development around the flats and the mass of the other buildings means that ventilation cooling is even more problematic as the outside air is hot. This is known as urban heat island effect. There may also be other flats and offices with air conditioning that throws additional heat to the outside, amplifying the issue. Evaporative cooling will not really work, neither will blinds or curtains as the heat is already in the room.
What is needed is greenery and water outside to cool the hard surfaces and cool the air so that cross ventilation can work. Air conditioning is about the only effective cooling in an overbuilt urban area but it will then add to the area overheating issues.
The London Homebuilding & Renovating Show will host these experts and more, offering free one-to-one advice and practical solutions for the UK’s most pressing home challenges. Claim free tickets via https://www.homebuildingshow.co.uk/pr-general-outlets
