Passive house instead of KFW70 with heat pump?

Hello,

...and the plan is a brine/water heat pump...
Now, just asking, a geothermal heat pump costs quite a lot of money with everything included, or quite a bit more than, for example, a gas system with solar support for hot water, but it is also a nice thing.

Kfw 70 and brine heat pump fit together quite well. Here, the substitution of the somewhat higher demand by environmental energy that is available year-round is aimed for. The costs for source development (vertical drilling) are quite high. This can be mitigated, for example, with a trench collector of narrow or slinky design (high own contribution!).
Well-planned brine heat pump systems achieve an annual performance factor >= 4.5. Possibly supplemented by a photovoltaic system. Sometimes a complete coverage can be achieved in the annual balance.
For heating and hot water, a common heat generator can be used.

With gas condensing boilers, connection costs are sometimes quite high regionally. Consumption (kWh/a) is higher. Solar thermal is actually mostly less economical in single-family houses but helps on paper ;-) The supply of solar radiation is subject to annual and daily cycles, therefore it is not constantly available year-round.

...Wouldn't it generally be better to consider building a passive house instead of a KFW70 house as a better investment? ..

A PH follows a different concept. Due to very good insulation, the heating energy demand is reduced. The demand for hot water remains unaffected by this. Heating loads are extremely low. Solar and internal gains intentionally play a major role in the energy balance. Ventilation losses account for a high percentage. The ventilation system plays a significantly greater role. The fluctuations in heating load are thus considerably greater here, albeit at a low level. Whether a slow floor heating system still makes sense here should be examined.
For heat generation for heating and hot water, often two separate heat generators of smaller capacity are required.

Reliable conclusions, as always, can only be drawn once the actual demand (capacity, energy) for heating and hot water has been determined beforehand (basic assessment).

Regardless of the intended solution, careful system planning/dimensioning is required in any case.

Best regards

Hm true, I didn’t even have the hot water in mind, it’s always the same... Solar gains are of course hard to calculate, for example if you lower the [Rollladen] so you’re not blinded by the sunlight reflecting on the floor in the living room, it looks different again

Hm true, I hadn’t even thought about the hot water, it’s always the same...

That’s right, thermal insulation does not help at all with hot water demand!

...Solar gains are of course difficult to calculate, for example if you lower the roller shutter to avoid being dazzled by sunlight reflecting on the floor in the living room, it looks different again

In the cold season as well as in the transitional period, solar gains in a PH are quite meaningful and usable or even absolutely necessary. In the hot season, on the other hand, they must be significantly "braked" by suitable measures. ;-) Cooling load calculation!

best regards