France has spent much of this summer under a heat dome that's pushed temperatures into the low-to-mid 40s°Cs in the worst-hit regions, and the UK has logged one heatwave after another since May, with the Met Office confirming one of the longest runs of 30°C+ days since 1976. In weather like that, a room with unshaded, sun-facing windows can be 5–10°C hotter than one where the heat never got in to begin with. Every fan or cooler you run afterwards is fighting a battle it didn't need to have.
Why windows matter more than people think
Glass is a poor insulator, and direct sun turns a window into a heat source that keeps radiating into the room for hours after the sun has moved on. Blocking that heat before it enters is almost always more effective than trying to remove it once it's already inside.
Reflective shades: the everyday option
Our Reflective Thermal Window Shade is self-adhesive and reflects sunlight back at the glass rather than letting it pass through, and it goes up in a few minutes with no tools or drilling. It's the option we'd recommend for most rooms — bedrooms, home offices, kids' rooms — where you still want some daylight but not the heat that comes with it.
Blackout panels: for the worst-hit rooms
For a room that gets hammered by direct afternoon sun, or one where you genuinely don't need the daylight (a nursery for nap time, a home cinema, a west-facing bedroom that turns into an oven by 5pm), the Blackout Window Insulation Aluminum Panel reflects roughly 90% of incoming light and heat. It's a bigger visual change than a reflective shade, but it's the strongest heat-blocking option we carry.
Pairing it with active cooling
Window insulation reduces how much heat gets in, but it doesn't remove what's already there or replace air circulation. Once the windows are covered, an evaporative cooler or fan has a much easier job — see our guide on cooling a room without central AC for the next step, or our desk cooling guide if the problem is really just one corner of a room.
Frequently Asked Questions
How much of a room's heat actually comes in through the windows?
Glass is a poor insulator and direct sun turns a window into an ongoing heat source, so unshaded, sun-facing windows are one of the biggest contributors to how hot a room gets — often more than people expect.
What's the difference between a reflective window shade and a blackout panel?
A reflective shade lets some daylight through while bouncing heat back outside the glass. A blackout panel blocks roughly 90% of both light and heat, which suits rooms that don't need daylight, like nurseries or home cinemas.
Do window films or shades damage the glass or leave residue?
Our shades and panels are designed to install and remove without damaging the glass, but always follow the specific product's application and removal instructions.
Is window insulation enough on its own, or do I still need a fan or cooler?
Window insulation reduces how much heat gets in, but it won't remove heat that's already in the room. Pairing it with a fan or evaporative cooler gives the best result — see our room cooling guide.