I'd argue that houses in the UK are not very well designed to keep warm which is why they overheat in the summer. I live in the Baltics, in a modern 4 bedroom house, and our annual energy consumption for heating is around 6000kWh - that's around half the average of a similar sized house in the UK, even though our winters are much colder.
My house is a bit older so doesn't have it, but new houses must have a heat recovery ventilator. Almost all of these have a 'summer bypass mode' which bypasses the heat exchanger, so effectively draws warm air out of the house. This is useful in the summer, as here although it can get to 30c+ in the day, at night it almost always drops to below 20c. The way our houses are built we have a lot of thermal mass, so if you can cool it down during the night, it will make it a lot more comfortable during hot days.
My house is a bit older so doesn't have it, but new houses must have a heat recovery ventilator. Almost all of these have a 'summer bypass mode' which bypasses the heat exchanger, so effectively draws warm air out of the house. This is useful in the summer, as here although it can get to 30c+ in the day, at night it almost always drops to below 20c. The way our houses are built we have a lot of thermal mass, so if you can cool it down during the night, it will make it a lot more comfortable during hot days.