Ventilation system in the warm summer

Hello everyone,

we have now been living in our new home with a central ventilation system for just over a year and are very satisfied so far.

The only issue is the temperatures in the attic (north-east side) in our bedroom, which are really not very pleasant in the evening. The room is not even facing south, and in the evening we have around 23 degrees Celsius in the room, although we open the windows wide in the morning, ventilate with cold air, and then darken everything afterwards.

I suspect that warm air from outside (logically) is continuously being blown into the bedroom by the ventilation system, causing the warm air to accumulate in the bedroom.

How do you deal with this, or is there anything to consider?

My ventilation system has been running at level 2 for several months now, as I especially felt in winter that there was fresher air in the room. Maybe I could turn this down again in summer?

Is there anything else that can be adjusted to improve the situation? Or in the end, is there no other option but to open everything wide and ventilate again for half an hour before going to bed?

I am grateful for any help, tips, and tricks.

With active heat recovery, the heat input through a central controlled residential ventilation system is very low. The people sleeping there generate significantly more heat.

With active heat recovery, the heat input through a centralized controlled residential ventilation system is very low.
The people sleeping there generate significantly more heat.

I’m more concerned that the ventilation system continuously brings warm air into the room – instead of (without ventilation) airing out in the morning and evening when temperatures are cooler. If you then darken everything, no significant heat should enter the room (without ventilation), correct?

But with ventilation, I don’t really have another choice, correct?

Or are there any special settings that can be made here?

Possibly through the bypass function?

No, doesn’t make a difference - I had the same issue with my wife last year during the heatwave summer. We turned off the ventilation for 3 days. We had the same temperature inside the house, only we felt uncomfortable because of the lack of airflow.
Around the wedding, we had 27°C inside the house with kfw 55. Asked a family with kfw 40: 28°C inside the house. Asked a family with a house from 1990: 23°C inside the house. I claim that the new houses no longer let the heat out. It was also often the case that at 5 p.m. we still had 25°C inside and thought "yay, today it won’t reach 27°C". Then you noticed how the brick transfers the solar heat inside (and outside), really radiates. Suddenly we had 27°C again... Luckily we have had an air conditioner in the living-dining area for a month including BAFA funding (which expired in 2023 - I applied in 2022).
Best regards

I'm more concerned that the ventilation system continuously brings warm air into the room

This is really negligible in terms of heating output.
I have already calculated this a few times here.
If needed, I can look it up again.

Or calculate it for you. What volume flow is the system set to?
How warm is it inside and how warm is it outside?

If you then darken everything, no significant heat should enter the room (without ventilation), correct?

That would mean that your house is so well insulated that you wouldn’t need to heat in winter if you didn’t ventilate.
But that’s not the case.
"Heat" flows through the outer shell just like "cold" does.
Maybe even worse, since the sun shines on the components, heats them up, and they then emit the heat inside.

And, as I said, people generate significantly more heat than a ventilation system.