ᐅ Ventilation in summer without a mechanical ventilation system can be challenging

Hello,
I have done quite a bit of research but still don’t feel any wiser on this topic.
Many sources suggest ventilating early in the morning or late in the evening during summer because it is usually cooler outside than inside at those times. However, these sources often also mention that the outdoor humidity should ideally be lower.
But when I check the data, humidity is usually quite high in the early morning or evening during summer, or am I mistaken? So when exactly should I ventilate on hot summer days? Not ventilating at all doesn’t help either if the indoor humidity becomes too high (around 65 percent in the basement, for example).

Can someone explain this to me or give me some advice?

I would appreciate it.

In my experience, the air is always dry in summer, especially after a longer period without rain. I know the advice to ventilate in the morning or evening applies to people with pollen allergies. If your basement is cool, you need to be careful when ventilating because warm air can condense on the cold basement walls. I can’t imagine there being issues with humidity in living areas during summer, no matter when you ventilate.

Sorry, but what are you trying to tell me with that? I have to ventilate at some point. And even in occupied rooms, you can do ventilation very wrong in summer. Just look at the current humidity levels for the next few days. They are generally quite high.
I can’t just leave my basement unventilated all summer either, especially when excessive humidity builds up there.

@Pinky0301 The air during summer here is not dry.

@TheKMKM

If it’s cooler outside than inside, just ventilate simply. PS: Users with mechanical ventilation systems turn off the ventilation during the day.

I haven’t been able to raise the humidity in our apartment anywhere near 40%, no matter when I ventilate. I figured it’s because the air is generally dry due to insufficient rainfall.
@tomtom79 I thought you shouldn’t or couldn’t turn off a mechanical ventilation system with heat recovery, because then the ducts might become contaminated? Our last mechanical ventilation system with heat recovery didn’t even have a switch.
@TheKMKM For basements, there are dew point-controlled fans, for example. However, I’m not sure if your basement is used for storage or as living space.

TheKMKM schrieb:

Humidity levels for the coming days

Where can I find these? The only percentages my weather app shows are related to the chance of rain.