ᐅ Air Source Heat Pump & Photovoltaics or Geothermal System – Which Providers?

Hello forum members!

This spring, we are starting the construction of our house... we are currently sorting through offers from construction companies and selecting various options. Our house (226 m² (2,432 sq ft) of living space excluding the basement) was designed with our builder at the end of last year. Everything has been approved by the local authorities, and the funding has also been applied for.

Now we face the big question about the heating system. According to the energy performance certificate, our house has a heating demand of 10,000 kWh per year. In various forums and from companies at trade shows, it is often said that ground source heat pumps are more efficient than air source heat pumps.

My question now is: how does it look if you combine an air source heat pump with a photovoltaic system compared to a ground source heat pump system? Which option is better in the long run? We have received an offer for an air source heat pump & photovoltaic system, which seems reasonable.

So, leaving aside the fact that the company is still relatively unknown, which system would you recommend?

I would be very grateful for your answers!!

Hello,

HanSolo78 schrieb:
... All approvals from the local authority are in place, and the funding has also been applied for. Now we face the big question about the heating system.

A bit late, but not too late.

HanSolo78 schrieb:
... According to the energy certificate, our house has a heating demand of 10,000 kWh per year.

This figure is not usable, as energy-saving regulations/KfW data are intended only for qualitative comparison purposes (official legal proof). For the design and sizing of heating systems, it is even inadmissible to use these figures (DIN 4701-10)!

HanSolo78 schrieb:
... You often hear that geothermal heat pumps are more efficient than air-source heat pumps.

That is correct. However, the better a building is insulated—that is, the lower the actual demand—the less significant the efficiency of the system becomes.

HanSolo78 schrieb:
... My question now is how a combination of an air-source heat pump with photovoltaics compares to a geothermal heat pump system. What is better in the long run?

There is no general answer to this; it must be calculated (or commissioned) based on the specific conditions and independently from sales interests.

HanSolo78 schrieb:
... We received an offer for an air-source heat pump & photovoltaic system, which looks basically okay.

What do you mean by "basically okay"? According to which criteria or based on what was this evaluated? If the actual demand (capacity, energy) for heating and hot water is not even known, making a decision is like looking into a crystal ball. Additionally, especially for air-source heat pumps, the COP and performance curves over the entire operating range are crucial.

Best regards

@€ruo

Thank you for your responses!

Our energy certificate lists a total heating load of 7.7 kW. I am unclear about the required power for domestic hot water, as this is not clearly specified. It should be around 3.7 kW.

Additional data for our house:

Heated gross volume: 932 m³ (33,000 ft³)
Average U-value: 0.25 W/m²K (0.04 BTU/ft²·hr·°F)
Brick wall thickness: 30 cm (12 inches) ceramic
Insulation thickness: 20 cm (8 inches)

What other data do you need so you can assist me further?

Hello,

HanSolo78 schrieb:
...So, our energy certificate shows a total heating load of 7.7 kW.

This value is not usable! An exact heating load calculation according to DIN EN 12831 (detailed method) is required.

HanSolo78 schrieb:
...Here it should be 3.7 kW.

How was this figure determined?

HanSolo78 schrieb:
...What other data do you need so you can help me a bit?

First, the actual demand (energy, power) must be known.

Best regards.