ᐅ New semi-detached house with 30 cm thermal insulation (T8) and air-to-air heat pump

Dear experts and readers,

We are considering the purchase of a newly built semi-detached house, scheduled for completion early next year. Since we are novices in this field, I wanted to ask the community whether 30cm (12 inches) T8 bricks (WLG08) combined with an air-to-air heat pump make sense.

From my initial research, this does not seem optimal regarding insulation and the expected electricity costs.

Thicker bricks might be possible, but the living area is already quite limited (approximately 7.5 x 8 meters (25 x 26 feet) footprint). I am also leaning more towards a gas boiler (proven technology?). The basement has 24cm (9.5 inches) waterproof concrete and 10cm (4 inches) thermal insulation.

The partition wall to the neighbor is only made of 2 x 15cm (2 x 6 inches) sand-lime bricks (including party wall panels). Is this sufficient for "standard" soundproofing?

I appreciate any feedback.
tolino123

The 2x15 sand-lime bricks are very good. Of course, it could be better, but this should be sufficient.

I don’t think much of air-to-air systems. Okay, the house gets warm, but tiles still feel very unpleasantly cold.
Better to have underfloor heating with gas or an air-to-water heat pump, or gas with underfloor heating and solar.
But it will definitely be more expensive.

Air-to-air systems—meaning without a hot water heating circuit and direct supply air—are not feasible with these exterior walls. When using air as the heat transfer medium, the maximum heating load is limited to 10 W/m² to maintain a comfortable indoor environment. Otherwise, either the air exchange rate becomes too high or the supply air is excessively hot at the point of entry. With 30 cm (12 inches) T8 insulation, you won’t achieve this; you would need significantly thicker walls, monolithic construction more likely around 49 cm (19 inches) T8 or preferably T7. For the building volume, this results in a considerable loss of interior space. A timber frame with cavity insulation plus exterior insulation might be possible with a 30 cm (12 inches) wall thickness.

Not everyone finds cool tiles uncomfortable.

Are you sure that a heat pump is offered without a hydronic heating system?

That must be a typo. A new air-to-air pump doesn’t make any sense here. They are not efficient enough for insulation purposes, and you wouldn’t get approval for that. Besides, where would the hot water come from?

tolino123 schrieb:
From my initial research, this doesn’t seem optimal in terms of insulation and the expected electricity costs.

Thicker bricks might be possible, but the living area is already quite limited (approximately 7.5 x 8 meters (25 x 26 feet) footprint). I am also leaning more towards a gas boiler (proven technology?).

Your initial research aligns 100% with reality. ;-)

However, you should quickly erase from your mind that heat pump compressors are not proven technology. This technology is over a hundred years old and is manufactured and installed millions of times every year.