If you want to keep your house naturally cooler this summer, the most important thing you can do happens before the day heats up: Close your blinds and windows by about 9 a.m., or before direct sunlight reaches that side of your home.
That’s the core idea behind an old-school home-cooling technique some call the “caveman method,” inspired by the naturally cool conditions found in caves.
To understand how it works, Country Living talked to Joseph Holman, a door and window specialist at Green Door based in the U.K., where June temperatures have surpassed record highs this year.
While it won’t replace air conditioning during extreme heat, it can help keep your home more comfortable and reduce how hard your AC has to work.
How does the caveman method help cool your home naturally?
“The golden rule of the caveman method is pre-cooling and early prevention,” says Holman.
To keep rooms as cool as possible, blinds should be closed no later than 9 a.m. or before direct sunlight reaches that side of your home—the exact time might vary based on latitude, cloud cover, and home orientation.
West-facing rooms are particularly vulnerable to overheating later in the day, when the afternoon and evening sun is at its strongest.
Closing blinds and windows early helps trap cooler indoor air before outside temperatures begin to climb. “Once that heat gets in, it’s incredibly difficult to get out,” explains Holman.
Does it still work effectively for smaller rooms?
Holman explains how consistency is even more important in compact spaces. Smaller rooms contain less air, so they tend to warm up quicker when exposed to direct sunlight or hot air from outside. Keeping blinds drawn and windows closed during the hottest part of the day helps prevent temperatures from rising too rapidly.
“Just ensure you don’t trap any active heat sources inside with you,” he urges.
What do you do after the sun goes down?
The key is to create effective cross-ventilation once outdoor temperatures begin to drop. Open windows on opposite sides of the flat or house to create cross-ventilation that helps flush out the residual warmth, explains Holman.
This encourages cooler evening air to flow through the home. Leaving them open overnight can help cool the building’s structure, making it more comfortable the following day.
Just note: Leaving windows open overnight is not recommended for those with ground-level rooms, as it poses a burglary risk.
What are the best companion hacks to boost the caveman method?
External shading can make a significant difference. Where possible, consider using awnings, shutters, or even large potted plants positioned outside to reduce direct sunlight. Indoors, reflective window film or even a simple layer of cardboard placed behind curtains can help bounce heat away from the room.
Holman explains: “The absolute best companion hack is blocking the sun before it hits your window glass.”
What hidden indoor heat sources will ruin the cave environment?
Household appliances, electronics, and lighting can all contribute to unwanted heat buildup. Items such as washing machines, dishwashers, computers, and older-style light bulbs generate warmth while in use. “Switch off unneeded appliances at the plug to keep your cave truly cool,” advises Holman.
What are the long-term, structural alternatives for these problem windows?
Invest in high-performance, sustainable glazing. “If you want a permanent fix, look into modern glazing advancements. Upgrading to solar-control glass, installing windows with integrated blinds (built between the glass panes), or adding external architectural shutters will permanently manage solar heat gain.”
As temperatures continue to rise, a few small adjustments can make a noticeable difference indoors. By combining early prevention with smart ventilation, Holman says homeowners can keep rooms cool, sleep more comfortably, and reduce the heat this summer.
