Calls for home insulation to cut energy demand, conserve heat and lower bills in in winter have have grown amid the energy crisis. But what impact do energy efficiency measures have in summer, especially as Britain get hotter because of climate change?
The government's own climate advisers, the Climate Change Committee (CCC), told Sky News the design of our homes risks "locking in" the impacts of climate change, such as extreme heat, which is becoming ever more likely.
Does insulation making your house hotter?
"Insulating homes has very little, if any, impact on the risk of overheating," said Professor Kevin Lomas from Loughborough University, who led the largest national study so far into overheating in homes.
Insulation can even help keep your home cool, because most types - certainly external wall and likely also cavity wall - will stop your home from getting as hot in the first place.
Other energy efficiency measures work both ways too: insulating pipes saves energy in winter by preventing heat from leaking - and so helping keep your home cool in summer.
The exception when it comes to insulation is if you have it on the inside of your wall, which can create a "small additional risk" of overheating by one degree Celsius or so, but only if your home isn't well ventilated anyway, explained Prof Lomas
But "other things like shading and proper ventilation have a much, much bigger effect and can reduce the internal temperature substantially", he said.
Why is my home so hot?
The main factors that let homes get too hot are "too much glazing, lack of shading, and insufficient capacity to well ventilate the home", said Julie Godefroy, head of sustainability at the Chartered Institution of Building Services Engineers (CIBSE).
Flats with "big windows at the expense of everything else" are often "designed without any consideration for what happens when the heat beats down on to these windows," Jonny Marshall, senior economist at think tank Resolution Foundation (RF).
"There's issues with through drafts as well," he said. In flats with only one side that faces outwards, "it's really hard to get air moving round".
Often these flats also have windows whose opening is restricted for safety reasons, but which prevent cooler air from coming in at night.
Loft extensions are also dangerous, "because you basically make this big black box on your roof and it just soaks up heat", said Mr Marshall.
And at the moment there is no requirement to design them in a way to avoid overheating, such as by avoiding too much glass, painting the roof white, or adding solar panels that create shade, he said.
"So people are actually making their houses worse at the same time as this problem [of heat] is getting worse," he said.
Why did the UK build hot homes?
For many years, policy focussed on energy efficiency without looking at overheating, said Ms Godefroy.
"There was a lack of looking at measures in the round," she said.
The CCC told Sky News a "holistic approach to buildings, considering energy efficiency, low-carbon heat, overheating and flooding risk is required to design safe and comfortable buildings for the future".
A new and more joined up approach has been promised as part of the government's Heat and Buildings Strategy. Standards were also improved in the latest building regulations.
But "more work is needed to make this a reality... and ensure that we are not building homes that will lock-in dangerous climate impacts in the future", said the committee's head of adaptation, Richard Millar.
How can you keep your house cool?
While there are many everyday things you can do to keep your home cool, other measures can be designed into homes.
One of the most effective is to "make more shade," said Mr Marshall. That could be shutters or drapes outside windows, as seen on Mediterranean homes, or designing balconies and ledges to cast shade.
Reflective film on glass windows can block out infra red light - the part of light that carries heat - as can types of glass with the right "g value".
Ventilation is also key - that means getting the right flow of air through the home, at the right time of day.
Green spaces and trees also have a cooling effect.
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