ᐅ Air-to-water heat pump + underfloor heating + controlled ventilation with heat recovery – individually adjustable room temperatures?

In my new KfW55 building, a air-to-water heat pump combined with underfloor heating is planned from the basement (required due to KfW55, crazy!) up to the top floor. Additionally, there will be a mechanical ventilation system with heat recovery, also covering from the basement up to the upper floors. Unfortunately, the mechanical ventilation system cannot be adjusted or turned off room by room.

Now my question to the experts here is: With this setup, is there any chance to keep a room (e.g., a bedroom or a basement room) significantly cooler (about 5°C (9°F) cooler, for example 16°C (61°F)) than all the other rooms (e.g., 21°C (70°F))? Or would you need an air conditioning system that then works against the mechanical ventilation? (Completely crazy idea...!)

HoisleBauer22 schrieb:

Now my question to the experts here: Is there any chance, with this setup, to keep one room (for example, a bedroom or a basement room) significantly cooler (about 5°C (9°F) lower, so around 16°C (61°F)) than all other rooms (for example, 21°C (70°F))? Or would you need an air conditioner for that, which would then work against the controlled mechanical ventilation system? (Totally crazy idea...!)

You won’t achieve a 5-degree temperature difference without additional measures. The house has an extremely well-insulated building envelope, so heat doesn’t escape outside but rather spreads throughout the house. Sure, you can simply turn off the heating loop in that room (and keep the door closed), but it won’t be enough to reach a 5-degree difference.

HoisleBauer22 schrieb:

... Unfortunately, the mechanical ventilation with heat recovery system cannot be adjusted or turned off on a room-by-room basis....

Now my question to the experts here: Is there any chance, with this setup, to keep one room (e.g., a bedroom or a basement room) significantly cooler (around 5°C (9°F) cooler, so for example 16°C (61°F)) than all the other rooms (e.g., 21°C (70°F))? Or would you need an air conditioning system that then works against the mechanical ventilation with heat recovery? (A completely crazy idea...!)

I consider it a myth that the mechanical ventilation with heat recovery system cannot be adjusted on a room-by-room basis. The control dampers at the supply and exhaust vents can usually be turned to adjust the airflow according to prior calculations. For this purpose, there is a large cover placed over the vents with an anemometer to measure air volume.

I haven’t measured recently, but I am quite sure that I have about a 5°C (9°F) temperature difference between the living kitchen and the bedroom (bedroom without heating, or for the original poster alternatively the airflow set to zero, bedroom door is closed 99.9% of the time).

We have very good summer thermal protection thanks to appropriate materials used in the exterior walls. I will gladly report on how it performs during the upcoming peak summer. I have only been living here since September 2021.

Five degrees Celsius (41°F) might just work if the door stays closed. It’s not really practical, though. Would I turn off the mechanical ventilation in that mold-prone room...? I don’t think so.

Why do you need such temperature differences? Would a wine cooler be an option?

i_b_n_a_n schrieb:

The control valves at the inlets and outlets can usually be adjusted by turning them to regulate the airflow and match the previously calculated settings. There is then a large cap placed over the valves with an anemometer for this purpose.

I need to ask my home builder about that.

Deliverer schrieb:

Mold breeding room

Do you think it could really get that bad? Supposedly, new buildings tend to be more on the dry side rather than too humid.

Deliverer schrieb:

Why do you need such differences?

According to scientific research, the ideal temperature for sleeping is between 16 and 19 degrees Celsius (61 and 66°F). So I would like to keep the temperature in that range. The problem is, of course, that the body loses a lot of moisture, and that moisture shouldn’t remain in the room for long. That’s why you shouldn’t turn off the controlled ventilation system, which I also believe.

HoisleBauer22 schrieb:

The scientifically determined ideal temperature for falling asleep is said to be between 16 and 19 degrees Celsius (61 and 66 degrees Fahrenheit).

You will reach that range. Even if it is "only" 19 degrees Celsius (66 degrees Fahrenheit), you are still within the optimal range.