Ventilation system in single-family house without effect = planning error?

They don't exist either. But you can just pull the plug.

We had a discussion with the heating engineer this week, and for example, the position of the valves was also discussed. That immediately made me think of this thread.

So how is the (perceived) air quality actually now after the appointment with the factory service and with a bit of time passing and above-freezing temperatures?

In the cold months, we have had fewer problems in recent years – rather, when it was very warm. Currently, according to the measuring devices, everything here is in the green zone. Only when the three of us (with child) slept in our small bedroom (approx. 14sqm with slope) did the CO2 level sometimes rise above 1000ppm, when the system was running at only 80 ccm/h at night.

So, purely based on the values, everything is in the green zone – as part of a photovoltaic expansion, our intake and air outlet will be moved from the roof to the north side of the house. I am curious whether this will have a significant impact. At the moment, we can’t really complain. The only thing is, the electricity consumption is a bit annoying, but we knew that beforehand (approx. 50 watts/hour).

So far, we have not received a recalculation of the system – I will follow up on that in the next few days.

We had a discussion with the heating engineer this week

Is that planned so late?
I had expected that it would already have to be prepared in the suspended ceiling.
How much say did he give you?

That immediately made me think of this thread.

Was it that catastrophic?
Did he have Vaillant plan ahead?
Are you getting one or two outlets in the bedroom?

Only the power consumption is a bit annoying, but we knew that beforehand (approx. 50 watts/hour)

Wasn't the original problem the preheating element at significantly subzero temperatures? At 50W/h I wouldn't make a fuss. But nice that it basically works now. You could also ventilate more at night and you won't always be three people sleeping in the bedroom.

Is it only planned that late?
I had expected that it would already have to be prepared in the filigree ceiling.
How much say did he leave you?
Was it that catastrophic?
Did he have Vaillant do pre-planning?
Do you get one or two outlets in the bedroom?

No, I was actually very satisfied – at least theoretically, I will only see practice in 6 months. Pre-planning has been done. Filigree ceiling between ground floor/upper floor is prepared with openings. The basement then requires core drilling, the basement ceiling was commissioned too early by the general contractor.

I was specifically concerned about the supply air in the bedroom. The heating engineer wanted to place it as far away from the door as possible, but the bed would be there. He would prefer to avoid the supply air above the bed if possible.

Wasn't the original problem the preheating coil at significantly below freezing temperatures? I wouldn't make a fuss over 50W/h. But it's good that it basically works now. You could also ventilate more at night and you won't always be sleeping three together in the bedroom.

Yes, fundamentally that is of course correct. But when I look at the entire energy balance of the ventilation system + filter + maintenance, I would probably still build the next planned house without a ventilation system and if I had to, definitely with an earth tube. And yes, we can surely still fine-tune the ventilation from the current setting. That's already not so bad. In combination with the photovoltaic system, the power consumption is relatively negligible, but it is there. And the promises about saving through the ventilation system are probably quite unfounded when you look at the overall balance of the system... (Not to mention the costs) I think that the bitterness about poor energy consulting (e.g. the heat in summer) also plays a part in my subjective assessment of the ventilation system. Therefore, I would not take ours as the "standard case" to assess a new building.