Nights….

[Flondra W Golfie]

#350

I’m considering replacing the windows in our home and keep seeing passive-house-certified windows advertised with extremely low U-values. What I can’t find much information about is their performance during summer heatwaves.

Has anyone noticed that highly insulated passive windows can actually make it harder for a house to cool down at night, especially if the outdoor temperature drops significantly after sunset? Do the insulated frames and triple glazing ever “trap” heat indoors longer than expected, or is this concern mostly theoretical?

I’d be particularly interested in hearing from people living in climates with hot summers and cool nights.

[Ivan]

#368

Hi,

From my own experience, I haven’t noticed passive-house windows making it harder to cool the house down at night. If anything, the biggest difference is during the day, when the interior heats up much more slowly. As long as I open the windows in the evening and get some cross-ventilation, the house cools down without any issues, even after a hot day. For me, shading and night-time ventilation have a much bigger impact than the windows’ U-value. I’ve never felt that triple glazing was “trapping” heat inside the house.

[Sabina]

#405

Hi everyone

I had the same concern before we replaced our windows, but in practice it hasn’t been an issue. From my perspective, the biggest difference has been that the house stays at a more stable temperature overall. On hot days, the rooms don’t heat up as quickly, and when the evening cools down, opening the windows is still enough to let the heat escape. I think good external shading and making the most of cooler night air have had a much bigger impact than the glazing itself. Overall, I definitely don’t regret choosing the better-insulated windows.

[Author]

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