Ventilation / Dehumidification of Living Spaces with Greywater Heat Pump

Hello dear forum community,

we will soon build a house for which the developer relies on a domestic water heat pump for ventilation and dehumidification. Primarily, air will first be drawn in from the guest WC, bathroom, and utility room and used for hot water generation. Air from other rooms flows in, so that a certain air exchange takes place. Fresh air should also be supplied to the living areas. I assume that wall openings to the outside will be necessary in the living areas, as otherwise, in my estimation, not much air will flow in.

How do you see this? Is this a good operating principle and quite common for a house of about 130sqm, or is it nonsense? Is the ventilation achievable with this sufficient to effectively prevent mold growth?

Thank you very much for your answers.

Hello.
You have significantly drier air in the house than usual through the system, so I think mold has no chance there.

The supply air then comes through small openings in the ceiling.

Hello, we also have this system. In the bathrooms, kitchen, and storage room, air is being extracted. Everywhere else, there are moisture-controlled wall boxes that allow fresh air to flow in. We heat the water to 51 degrees and so far it works quite well.

However, the drier air inside the house is only present when there is no particular humidity outside either. In summer, it was not possible without an electric dehumidifier when it was especially muggy again. How it will behave in winter remains to be seen.

However, if the hot water tank is completely empty, it takes about 10 hours for the temperature to be reached again (without switching on the heating element). This should be taken into account if you like to take a full bath in the morning.

The consumption from June until today is about 300 kWh

Hello.
How large is your water tank?
Ours is only 180 liters and easily enough for 5 showers when we have guests.
We have the water set to 63 degrees.

Our tank has a capacity of 200 liters. However, we have a 190x90 bathtub with a usable volume of 210 liters.

But it will not be filled to the brim with 45*C hot water, and besides water, a person is supposed to go in as well.