ᐅ Stop heating a heated basement?

Hello everyone,

I have purchased an older house built in 1970 and will be moving in soon. The house has a full basement, which also includes a laundry room.
The basement walls are described as: "KSV 1.8/150, thickness 36.5cm (14 inches), with an external waterproof coating in the ground."
There are many windows in the basement, some of them only protected by metal grilles. The basement itself is separated by a door, so it is not an open space.

The basement is fully heated, with many radiators installed. The previous owner typically kept the heating on 2-3 radiators in the basement during winter, and it was warm when down there.

However, we rarely or almost never go into the basement now, so we definitely don’t need it heated to 20°C (68°F). We also plan to replace all the basement windows with double-glazed units because the old grilles don’t really provide much protection.

What risks might arise if we turn off the heating or limit it to a maximum of 16°C (61°F)? Could this cause mold growth? What’s your take on this? The main goal is to save energy since keeping the basement heated all the time is simply too expensive.

The answer depends largely on how much moisture is present in the basement. The house is 50 years old. At that time, basements were not made completely watertight. Is there any stagnant water, a high groundwater level, or seepage water? So far, the windows have only been partially barred, allowing good air circulation, which would be blocked by installing new windows.

Here’s what I would do: install the new windows, turn off the heating, and measure the moisture levels both in the air and in the walls. As long as everything stays within acceptable limits, you can proceed with your plan.

For a "standard" basement from this construction period, I would leave the windows as they are. Unlike the house, the basement can actually breathe. The money saved can then be spent on insulation on the basement ceiling. You will really notice in winter how warm the floor becomes – otherwise, cold floors take on a very literal meaning. This also cools the basement down by a few degrees, so you will need significantly less heating upstairs.

Benutzer200 schrieb:

For a "standard" basement from this construction period, I would leave the windows as they are. Unlike the house, the basement can actually breathe. The money saved can then be used to insulate the basement ceiling. You’ll really notice in winter how much warmer the floor becomes – otherwise, cold feet takes on a very literal meaning. This also cools the basement by a few degrees, and you’ll need to heat significantly less upstairs.

Could I also install new windows and additionally insulate the basement ceiling? Then ventilate occasionally in winter and keep it closed in summer? Or do the old windows absolutely have to stay?

There is also a laundry room in the basement. Could that theoretically cause problems? Or could I just leave the window open while the laundry is drying?

Or would trickle vents combined with an exhaust fan possibly help here? The basement is not used as living space anyway, and it is in a quiet area.

taskyyy schrieb:

Could I also install new windows and then additionally insulate the basement ceiling? And then occasionally ventilate in winter and keep windows closed in summer? Or do the old windows have to remain?

That depends on how dry or damp the basement actually gets. Occasional ventilation won’t work if some moisture keeps entering the basement. It’s difficult to assess from a distance.

taskyyy schrieb:

There is also a laundry room in the basement—could that theoretically cause problems? Or could I simply leave the window open while the laundry is drying?

Theoretically yes, it’s a ventilation issue ==> see above.

taskyyy schrieb:

Or would trickle vents in the window frame possibly help here if combined with an exhaust fan?

Probably (just a feeling) a properly sized trickle vent in the window frame would be sufficient to provide constant ventilation. Basically like now, but with new windows.

taskyyy schrieb:

Or would trickle vents in the window reveal possibly help here with an exhaust fan?

Just an idea, no idea if it makes sense: install windows (with or without trickle vents) and remove part of the rubber seal. Then, at least I imagine, air exchange might happen more easily. But maybe that’s actually a bad idea and I just don’t know it.
I have been thinking about this for our home because our builder does not install windows with trickle vents, and we did not want to add a mechanical ventilation system.