ᐅ Air-to-water heat pump or gas heating combined with controlled ventilation in a 135 sqm single-family home?

M4rvin schrieb:
Thanks for your replies!

We will soon have the plot and will then build with a local developer.

The mechanical ventilation with heat recovery would be too expensive for me if I had to buy it in addition to the air-to-water heat pump.
But if I could save some money now with a gas boiler, mechanical ventilation with heat recovery might be possible again.

We would definitely like to have mechanical ventilation with heat recovery, my wife has some issues with pollen...

Go for it, and everyone will be happy with the comfort. For me, there is no question, especially because of the allergy.

The price of your mechanical ventilation with heat recovery already suggests it, but I would recommend opting for a central mechanical ventilation system with heat recovery. From an energy cost perspective, it might not pay off, as @Tego12 has already mentioned. Just to add, this is not to give the impression that mechanical ventilation systems with heat recovery consume a lot of electricity. Rotary heat exchangers naturally use a bit more power than plate heat exchanger systems because the rotor, in addition to the fans moving the air, must continuously rotate—albeit slowly. For the Zehnder ComfoAir Q350, which seems to be popular, the power consumption at setting 4 (out of 8) is specified as 44W, which likely corresponds to the airflow of normal ventilation, assuming the unit has been properly configured. So, the energy use is quite moderate. For me, the “M” in mechanical ventilation with heat recovery primarily stands for comfort. I am happy to keep a weak light bulb on all day in a figurative sense, because the ventilation system consumes about as much energy. For the benefit of always having fresh, filtered air (including pollen), I consider it a worthwhile investment.

I have to say that every euro spent on the controlled residential ventilation system was worth it.

Please do a rough comparison of your energy consumption (gas/electricity) using Check24. Then calculate and compare to see if and when it becomes cost-effective. Keep in mind that a gas connection also has to be installed in the house.

Finally got confirmation today! It is possible to forgo solar, so we will only use gas plus controlled mechanical ventilation!

M4rvin schrieb:
Finally got confirmation today! It is possible to forgo solar and we will therefore only use gas plus a controlled residential ventilation system!

Since I have also looked into this issue, I would be interested to know exactly what and especially who confirmed this to you?

I have studied the topic a bit and came to the conclusion that, due to the Renewable Energies Heat Act in combination with the 2016 Energy Saving Ordinance, this is no longer that easy?

As a substitute measure for (for example) using solar radiation to cover 15% of the heating and cooling energy demand, only the following would be possible:

1. Residential ventilation with heat recovery from exhaust air, which must save/cover at least 50% of the total heating demand of the house
( § 7 paragraph 1 no. 1 a) Renewable Energies Heat Act)

2. 15% better insulation than required by the 2016 Energy Saving Ordinance and a 15% lower annual primary energy demand
( § 7 paragraph 1 no. 2 in connection with
VII no. 1 of the annex to the Renewable Energies Heat Act)

Or are you building a KfW55 house?

With a KfW55 house, does one automatically achieve a 15% lower annual primary energy demand and 15% better insulation than the Energy Saving Ordinance?

Aliban2014 schrieb:
Does a KfW55 house automatically have a 15% lower annual primary energy demand and 15% better insulation compared to the Energy Saving Ordinance?

Qp 55% (energy demand)
H't 70% (insulation)

These values are calculated by the energy consultant who prepares the thermal protection certificate or the KfW documentation, if a KfW program is used.