Construction project - ventilation system, heating - your experiences?

Our controlled residential ventilation system (for 180sqm) cost about 12,000 euros, definitely not more, and I would never want to go without it again. To ventilate properly, you would have to open all the windows about 5 times a day, after which it's freezing cold inside during winter and in summer you have the heat plus about 30 flies in the house. Besides, people usually have some decorations on the windowsill anyway, so you can't just quickly open every window, or like in our case, all the window handles are locked. It is simply a very big gain in comfort with a controlled residential ventilation system, always fresh air that is also pre-warmed when it comes into the house. When it comes to heating, it's a matter of taste; we have gas because the noise of an air-water heat pump simply bothers me and we didn't want to disturb our neighbors with it either.
Best regards
Sabine

Because every ROI and TCO analysis shows this. In other words, the investment and maintenance are more expensive than what the system saves during its lifetime. I don't think it's bad either, but economically not really profitable.

Why not? Is it that expensive? My dad has it on the roof and is enthusiastic. Ok, he is enthusiastic about technology anyway. But he says he gets boiling water from the roof on sunny winter days.

Investment costs minus expected savings. If you decide on a heat pump, you should also refrain from it for other reasons. You then mix a high-temperature system with a low-temperature system. To reconcile this, you need a system with a mixer. This complicates the control, most heating engineers already have problems with heat pumps without solar thermal. You can consider the result. The efficiency of the heat pump also suffers even with an optimally controlled system, which brings us back to sentence 1.

Solar thermal energy is nowadays used at most to legitimize the gas heating system for the energy saving ordinance. Then it might "pay off," because it is the cheapest pro-gas way. Some general contractors, on the other hand, install mediocre heat pump concepts because that is cheaper than gas + ST and because the heat pump helps to make consumption look good on paper, while saving on real insulation.

Controlled residential ventilation is purely a comfort decision, about €11,000 investment for us. Saves nothing. For us, the best decision was to install it.

Heat pumps are suitable for new buildings. But: the planning including the planning of the underfloor heating urgently needs to be supervised by the builder themselves.

Whether the heat pump pays off depends on what you pay for it. The more the builder is able to take care of it, the more you save compared to gas. See notes on the ring trench collector from Daniel.

Gas has THE advantage that planning errors hardly affect consumption costs, meaning you don't have to take care of it yourself and can expect moderate consumption. But if you later switch from gas to heat pump, it would have been better to have planned properly from the start (underfloor heating).

Best concept in my opinion:
- Insulation roughly towards KfW55, depending on costs
- Ring trench collector + BAFA subsidy or air-water heat pump, if possible bought by yourself and/or strongly coordinated.
- Roof as full as possible with photovoltaics
- Controlled residential ventilation optional

Our architect only had opinions to offer about the technology. If we had listened to that, it would have been more expensive in purchase and consumption.

Solar thermal energy is nowadays used at most to legitimize the gas heating system for the Energy Saving Ordinance. Then it might "pay off," because it is the cheapest way pro-gas. Some general contractors install mediocre heat pump concepts, because that is cheaper than gas + solar thermal and because the heat pump helps to make the consumption look good on paper, while in reality they can save on insulation.

A heat pump is appropriate in new buildings. But: the planning including the planning of the underfloor heating urgently needs to be monitored by the builder themselves.

Whether the heat pump pays off depends on what you pay for it. The more the builder can take care of themselves, the more you save compared to gas. See Daniel's notes on the horizontal ground collector.

Gas has THE advantage that planning errors hardly affect the consumption costs, meaning you don't have to take care of it yourself and can expect moderate consumption. But if you switch later from gas to a heat pump, you would have been better off planning properly right from the start (underfloor heating).

Good post!

Still a few questions for understanding: why does a gas heating system not affect consumption in case of planning errors? What do you mean by planning errors? That you take a heating system that is too big or too small? Yes, I imagine that is also difficult with a heat pump, installing the right one (in terms of capacity/size).

But because you also mentioned underfloor heating. I can operate that well with both gas heating and the air-water heat pump, right?

Oh yes, and why do some general contractors install rather poor heat pumps and save on insulation? Poor insulation means that the heat pump has to work harder (switching on the electric heater earlier, etc.) and then no more nice consumption figures on paper?

What do you mean by "the builder should take care of / monitor the heat pump"? The correct subsequent configuration or during the selection?

With heat pumps, you can do a lot wrong. Buffer tanks and especially poorly planned underfloor heating. Just google it.. there are hundreds of posts.

With gas, you simply increase the temperature of the heating and that's it. With a heat pump, every degree costs efficiency. In addition, heat pumps are often operated incorrectly: heating rod, wrong heating curve, etc. These are all risks that don't really exist with gas.

I am absolutely pro-heat pump, but heat pumps are unfortunately not a walk in the park.