UPDATED 14Aug2020 + videos below: As summer heat comes on each year, I always get subscriber questions like this one:

“Why are my upstairs room so hot in summer? Even with the central A/C running I can’t sleep. I hate paying to have the basement and first floor freezing, while I’m sweating upstairs!”

Second-level rooms often get overheated in summer because of the design of forced-air heating systems that central air connects to. Forced air furnace systems in heating climates always include louvred floor registers that are located to deliver heated air in winter, not cooled air in summer. Ducts can’t be changed, and while this sounds like bad news, there is another solution that works really well for getting rid of that bubble of upstairs hot air that’s making you miserable. It all comes down to openable skylights of the kind you see here.

Beat the Heat Upstairs Rooms

Many people are astonished at how much better central air conditioning works when a few openable skylights are installed in second storey ceilings. In fact, openable skylights make any home much, much cooler, even if you don’t have air conditioning turned on at all. By opening the skylights just an inch or so during the day, hot air is allowed to leave your home, making room for cooled air from your central air conditioner to rise up and cool overheated upstairs spaces. I know it sounds strange, but opening skylights actually helps A/C work better.

Beat the Heat: What About When It Rains?

Many skylights can open, but the best are electrically operated models that automatically open and close on a schedule, and close quickly on their own when it starts to rain. What’s the point in having cooler upstairs rooms if your floor is wet when you come back from work? The trouble with most electrically operated skylights is that it’s very disruptive to string wires to them in a retrofit situation. That’s one reason I like solar skylights. They don’t require wires to deliver power, but draw power from on-board batteries kept charged by photovoltaic cells built right in.

I’ve installed solar skylights myself and live with them, and they work perfectly. Just pop them in like standard skylights and enjoy electric operation with automatic rain closure. You can even open solar skylights during power failures, cooling your home when air conditioning can’t operate. VELUX is currently the only company that makes solar-powered skylights, and I’ve never seen anything as good as the models they provide. Their solar power system also includes solar-powered blinds that can operate using a touch remote or on a schedule. Blinds are especially useful for summer cooling action because they block out sun while the skylight is open and ventilating. It’s also pretty nice to wake up to a gently opening blind in the summer, rather than the blare of a clock radio.

Beat the Heat: “My Air Conditioning Finally Works!”

This is the kind of good news I usually hear from people who get openable skylights installed, but in my experience the benefits of skylights go beyond just air conditioning that finally works upstairs. Top-of-house ventilation means you won’t need air conditioning nearly as often as before. Open up the skylights remotely from any part of the house and you’ll immediately feel the breeze flowing through all rooms through opened windows. Your house will cool off much faster at night when all the hot air can escape through the roof. Add to this the emotional benefit of much more natural light indoors, and you’ll begin to see why I like skylights so much.

Click the video below to see me installing a modern VELUX solar skylight, and how automatic rain closure works in action