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

Hi everyone!

We want to build a single-family house with about 135 sqm (1453 sq ft) without a basement. Originally, we planned to install an air-to-water heat pump (Dimplex, ELCO, or Viessmann), but we just learned that the plot has a gas connection. We had actually ruled out gas because we did not want to install an external gas tank. (But the outdoor heat pump unit isn’t very attractive either...) The developer would credit us €4000 for a gas condensing boiler plus a solar system with two flat plate collectors.

Is it also possible to skip the solar system and instead install a ventilation system with heat recovery? I would like to have ventilation, but €12,300 is too expensive for me!

We are leaning toward 17.5 cm (7 inches) calcium silicate blocks, but without extra cost, 24 cm (9.5 inches) calcium silicate blocks or brick would also be possible. (EDIT: pitched roof and underfloor heating)

Thanks in advance,
M4rvin

We are currently facing a similar decision.

A 150 sqm (1,615 sq ft) single-family house without a basement, featuring underfloor heating. The plot size is about 900 sqm (9,688 sq ft).

Originally, everything was planned to run on gas with solar thermal for hot water.
As an alternative, we can now install an air-to-water heat pump (Remko WKF120).
The additional cost is about €5,500 plus an optional sound enclosure for €2,000.
The gas connection and related costs have already been excluded.

I am trying to list the pros and cons. So far, it’s more of a gut feeling decision for me. It’s quite difficult to base it really on facts at the moment.

M4rvin schrieb:

Is it also possible to skip the solar system and instead install a ventilation system with heat recovery?
I would have liked to have ventilation, but 12,300€ is too expensive for me!

It is possible, but the responsible person should be able to tell you how exactly, with which bricks, etc.
But why, if it is already too expensive for you?

There is no clear answer in advance as to which option will be more cost-effective to purchase. This needs to be determined or estimated specifically. The basis for this can (only?) be provided by an energy consultant (the person who carries out the energy efficiency calculation). They will specify what is necessary to obtain building permit / planning permission and can advise on how different measures can be combined. Afterwards, investment costs can be compared and operating costs estimated (total cost calculation).

Are you buying from a developer, or do you already own the land and now want to build with a general contractor (GC) / main contractor?

What can be said quite generally is this: You will never make a central ventilation system with heat recovery cost-effective (the electricity and maintenance costs alone almost negate the energy savings). There will always be cheaper solutions to meet building standards.

However, don’t underestimate the huge comfort benefits this system provides. I would never want to live in a house without a ventilation system again; it’s simply brilliant (air quality, no annoying manual airing, windows closed during pollen season with the appropriate filter inserted, and so on). The price you mentioned is not excessively overpriced but rather quite realistic for such a system.

I can only agree here: your energy consultant needs to run the numbers… there are many solutions available.

Thank you for your replies!

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

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

So, we would definitely like to have a mechanical ventilation system with heat recovery; my wife has some issues with pollen...