ᐅ Air-to-water heat pump, gas heating, solar thermal systems in prefab homes – advantages and disadvantages?

Hello everyone,

I am honestly quite at a loss.

This year, we are building a prefab house consisting of two bungalows, each measuring 10.5 by 10.5 meters (34 by 34 feet), connected by a flat-roofed corridor. The house is fully basemented, and under one bungalow, there is a garage. (I’m not sure if that matters.)

We definitely have:
- Underfloor heating
- A mechanical ventilation system with heat recovery
- And a fireplace, just for supplemental heating when we feel like it.

Currently, there are two adults and two children living here, and it’s not impossible that a third child might be born.

The areas to be heated include the two living bungalows, the corridor, and one finished basement area — in total about 350 square meters (3,770 square feet). Would you also heat the garage with the central heating or connect it to the ventilation system? Considering the exhaust fumes. The garage will otherwise be used for gatherings about three times a year.

A ground-source heat pump is off the table. The remaining options are an air-to-water heat pump, heating oil, and gas.

Could you list the pros and cons of these heating methods? And would you generally consider planning with solar thermal systems or photovoltaic panels? I know that nowadays they mainly cover your own energy needs, but it’s still uncertain whether they pay off...

I would really appreciate lots of tips and discussions, as we need to make a decision soon and I have no clue.

Thanks in advance.