ᐅ Heating System Planning

Hi everyone,

Since my construction project is now nearing completion, I would like to focus on choosing the right heating system for my house.

The energy-saving regulation confirmation for KfW 70 has been completed.

Now I would like to get advice from a professional about the right heating system. Since we do not have a gas connection and pellets or wood are not an option for me, the heat pump is basically the only choice left for our house. The area to be heated is about 110-120m² (1,185-1,292 sq ft).

Over the past two weeks, I visited three heating companies, and each offered me a different system. Therefore, I would like to hear the opinion of an expert. I have read a lot about heat pumps being quite inefficient, but I understand this can definitely depend on the selection of the entire system components. I want to avoid making a mistake here, as I have many questions in mind.

-Air-source heat pump or ground-source (geothermal)?
-How to heat domestic hot water (separately or with the heat pump)?
-Buffer tank?
-Additional electric heating element?
-Photovoltaic system?

Surely someone here has experience with a competent consultant or is a professional themselves and can answer my questions.

PS: I can upload the documents for the energy-saving regulation proof if needed.

I’m looking forward to hearing some experiences or recommendations from experts.

Best regards,
Kai

stiff80 schrieb:
Since my construction project is now nearing completion

Your construction project is almost finished, and you have the KfW70 certification, but you still don’t know which heating system you will use?! How is that supposed to work? The heating system has a significant impact on the primary energy demand of your house and thus on meeting the requirements of the energy-saving regulations.

stiff80 schrieb:
I have already read too much about heat pumps being very inefficient.

Heat pumps have been around for a long time… which exact type you mean remains unclear here.
Ground-source heat pumps (water-to-water) are very efficient but more expensive to install – depending on whether you use horizontal ground collectors or deep boreholes, the cost varies from somewhat higher to much higher.
Air-to-water heat pumps are less efficient but don’t require any excavation.
No buffer tank is needed for the heating system—regardless of the heat pump type.
Almost all have an electric heating element, which is really only needed if the system is incorrectly sized and possibly for the Legionella prevention program—and of course for screed heating—which in your case is already dry, right?!
You can install photovoltaics, but you shouldn’t expect a great return on investment anymore.
Upload the energy-saving regulation documents—I'm quite interested in them.

By the way, the heating system doesn’t stand alone. For the right choice, you should also consider the underfloor heating and floor coverings.

I’m not an expert, by the way.

BeHaElJa schrieb:
Your construction project is nearing completion and you have the KFW70 confirmation, but you’re still unsure which heating technology to use?! How is that supposed to work? The heating system has a significant impact on your home's primary energy demand and thus on meeting the energy-saving regulations.

Heat pumps have been around for a long time... which type exactly you mean remains unclear here.
Ground-source heat pumps are very efficient but more expensive to install – depending on whether you choose a horizontal ground collector or deep borehole, the cost varies from somewhat to much higher.
Air-to-water heat pumps are less efficient but don’t require any excavation.
No buffer tank is needed for the heating system – regardless of the heat pump type.
Almost all have an electric heating element, which is generally only needed if the calculation is off, possibly for the legionella prevention program – and, of course, for screed heating – but your screed is already dry, right?!
You can install photovoltaic panels – but you won't achieve outstanding returns anymore.
Upload the energy-saving regulation documents – I’m really interested.

By the way, the heating system should not be considered in isolation. For the right choice, you should also factor in the underfloor heating and flooring materials.

I am not a professional, by the way.

I think I expressed myself a bit incorrectly! By completion, I meant the contract awards for the shell builder, carpenter, and roofer...

The energy consultant calculated based on an air-to-water heat pump...
Now I tried to do some research online, and these questions came up.

The calculation is not correct for the heat transfer coefficient (HT value) – no windows seem to be taken into account, or am I mistaken? It also doesn’t feel right. An air-to-water heat pump is generally not a bad choice – but without a heat load calculation, it is difficult to determine the proper sizing.

How do you come to the conclusion that no windows have been included?
And what feels off to you?

I might be wrong – you have insulated your top floor ceiling and the roof? Maybe that’s why – unfortunately, no surface areas are shown. Otherwise, the floor slab, exterior wall, and under-eaves area are all roughly around the heat transfer coefficient (HTC). The roof and upper floor ceiling perform somewhat better. The windows are noticeably worse. How much percentage of window area do you have?