If you're struggling to sleep during the current heatwave, a new study suggests you'd be better off sleeping in the lounge.
Academics at Loughborough University say they've performed the largest and most comprehensive study to date on overheating in English homes.
They found overheating to be more prevalent in bedrooms at night than in living rooms during the day in all English dwellings except flats and bungalows.
More than 4.6 million homes in England are experiencing overheating during the summer, they claim, but bedrooms are more affected by heat than living rooms.
The researchers also found that living room overheating was 30 per cent greater in flats than any other dwelling types, including multi-storey homes.
The study follows a heatwave health alert issued by Public Health England this week, as Brits struggle with stifling temperatures around the 86°F (30°C) mark.
Overheating is even more prevalent in bedrooms at night than in living rooms during the day, according to the study by experts at Loughborough University
HOW TO SURVIVE THE HEAT
- Stay indoors
- Close curtains on rooms that face the sun to keep indoor spaces cooler
- Drink plenty of fluids and avoid excess alcohol
- Never leave anyone in a closed, parked vehicle, especially children or animals
- Try to keep out of the sun between 11am to 3pm
- Walk in the shade, apply sunscreen and wear a wide brimmed hat, if you have to go out
- Avoid exercising in the hottest parts of the day
- Make sure you take water with you if you are travelling
- If anyone feels unwell with a high temperature during hot weather, it may be heat exhaustion or heatstroke
Professor Kevin Lomas, from Loughborough's School of Architecture, Building and Civil Engineering, who is lead researcher on the study, has pointed to climate change.
Threats from climate change are of worldwide concern – and global temperatures are likely to be 2.7°F (1.5°C) above pre-industrial levels by 2052, he believes.
'Heatwaves will increase in frequency, intensity, and duration, and so will the health risks associated with them,' he said.
'With the majority of fatal heat exposures in developed nations occurring indoors, the findings of our study show just how many homes in England are at risk of overheating.'
The phenomenon of ground floor living rooms being cooler than bedrooms on the upper floors can be explained by simple thermal physics.
In houses with two or more storeys, the ground floor is better shaded by the surrounding environment than the upper floors.
The bedrooms in contrast, are likely more exposed to the sun's glare and may be directly below the hot roof or attic space, according to the university.
And because hot air rises, warm air generated during the day will rise to the higher spaces. At night, meanwhile, cool air is more likely to pool on the ground floor.
The research is based on an assessment of 750 English homes where houses were monitored and residents filled in questionnaires.
The results from the sample allowed the experts to make projections for the total number of English households (24.17 million, as of 2018).
The findings indicate that in England, 4.6 million bedrooms and 3.6 million living rooms were overheated.
Occupant behaviour may be another factor – during the day, occupants are more likely to 'manage' curtains and blinds on the ground floor than in the bedrooms above.
In flats and bungalows, both living rooms and bedrooms are on the same level, and are often not on the ground floor.
So there are fewer, if any, systematic differences between the thermal physics occurring between the living room and bedroom.
Living room overheating was also more prevalent in households living in social housing, with low incomes or with members over state pension age.
There are 24.17 million households in England, as of 2018, according to the research paper. The findings indicate that in England, 4.6 million bedrooms and 3.6 million living rooms were overheated
'With the most vulnerable members of our society – the elderly, the very young, those living in deprived areas, and those with chronic physical and/or mental health conditions – being most at risk, action needs to be taken now to mitigate the dangers increased temperatures will bring,' said Professor Lomas.
The team have called for better control over the methods of construction and refurbishment of flats and targeted public health messaging around overheating.
Better construction methods could include the use of more ventilation options and light-coloured building materials to reflect light.
Designing buildings that mutually shade each other and introducing more shady plants near to ground floors could be other options.
'With British summers getting hotter, we're all feeling the heat a lot more,' said study author Helen Garrett, principal consultant at Building Research Establishment (BRE).
Public Health England issued a heatwave health alert earlier this week, as people in the country struggle with stifling temperatures. Pictured, Bournemouth beach in Dorset on July 22
'This research identifies where some of the biggest challenges are – in flats, in our bedrooms at night, and for older and poorer households.
'The construction industry can use this to think about how to build future homes, and retrofit existing homes, which will be more comfortable in heatwaves like the one we're enduring now.'
The research, conducted in partnership with BRE, focused on the summer of 2018 – England’s hottest summer to date.
During summer 2018, there were four heat waves, resulting in 1,067 excess deaths, with far more deaths being recorded in London than elsewhere in England.
WHAT CAUSED THE SUMMER 2018 GLOBAL HEATWAVE?
There are several leading theories as to what caused the global heatwave, according to University of Reading climate scientist Professor Len Shaffrey.
1. Climate Change: Temperatures are increasing globally due to the burning of fossil fuels increasing concentrations of atmospheric carbon dioxide. The global rise in temperatures means that heatwaves are becoming more extreme. The past few years have seen some record-breaking temperatures in Europe, for example the 2015 heatwave and the 2017 ‘Lucifer’ heatwave in Central Europe. Unusually warm summer temperatures have been recorded elsewhere, for example in Canada and Japan, and climate change is very likely to have played a role here as well.
2. North Atlantic Ocean Temperatures: Temperatures over the North Atlantic Ocean can play a role in setting the position of the jet stream, which in turn has a profound impact on the weather we experience in the UK and Ireland. This summer has seen relatively warm North Atlantic Ocean temperatures in the subtropics and cold ocean temperatures to the south of Greenland. These are thought to be influencing the high pressure over Europe and pushing the jet stream further northwards.
3. La Nina: Every few years, ocean temperatures in the Tropical Pacific swing between being relatively warm (known as El Nino) and cool (La Nina). Since October last year the Tropical Pacific has been in a La Nina phase. La Nina is sometimes associated with cold winters in North Western Europe (for example the winter of 2010/11 and the recent cold spell in March 2018). However, this year’s La Nina had started to weaken around April and had almost gone by June when the current dry spell in the UK began.
4. It’s the weather: The above factors influence type of the weather get in the UK and Ireland but good or bad luck also plays a role, especially for very unusual weather such as the current hot and dry spell. This summer is no different and the hot and dry weather is partly due a combination of North Atlantic Ocean temperatures, climate change and the weather. Should weather patterns continue as they are then we might expect this summer will turn out to be as hot and dry as the extreme summer of 1976.