ᐅ Is Solar Worthwhile for KfW 55 Houses?

Created on: 24 Jul 2013 13:48
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Sambi1511
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Sambi1511
24 Jul 2013 13:48
Hello,

Our house is planned, and the energy consultant has already done the calculations. However, he was not really able to give a clear assessment regarding the cost-effectiveness of the construction project. We achieve the KfW 55 standard with the following setup:

Floor: No basement, perimeter insulation under the slab
Walls: Sand-lime brick 17.5cm (7 inches); 14cm (5.5 inches) insulation, 1.5cm (0.6 inches) air gap, 11.5cm (4.5 inches) facing brick
Windows: Triple glazing

Heating: Ground-source heat pump with a combined storage tank for hot water; underfloor heating throughout the entire house.
Additionally, a solar thermal system (7.9m² (85 ft²)) for hot water preparation in the combined storage tank.

We will also have a fireplace, which can have water jackets, but this was not considered in the calculations.

Now my question: Without the solar system, we don’t reach KfW 55 but only KfW 70. The energy consultant says that the solar system only becomes cost-effective with 3.5 or more people in the household.
Can anyone share approximate cost information? So, do I have to invest much more than the €2,500 I save by achieving KfW 55?

Does a fireplace with water jackets make sense in this setup?

Many thanks for any experience or feedback on my questions.