ᐅ New Construction with a Granny Flat – Heating System and KfW Financing Questions

Created on: 10 Apr 2021 23:07
D
derBensch
Hello housebuilding friends,

Since I have a large thread with many questions, I will separate the individual questions. It was quite a surprise that we got a building plot.

A house construction is planned. New build according to KFW40+ standard (currently still undecided whether KFW55, 40, or 40+). Using the new KFW subsidy would cover the additional costs one-to-one.

Yesterday during planning, I learned that for the new build, I will get "2x air-to-air heat pump heating" installed. Since I can apply for the KFW subsidy twice, I need 2 heating systems. What sense does that make? Well, in the end, I will probably get the heating for the secondary apartment (SA) at no extra cost.

The house (timber frame prefab house) without a basement, spread across two levels. 160 sqm (1720 sq ft) main apartment, 65 sqm (700 sq ft) secondary apartment.

Ground floor – main apartment + secondary apartment and the utility room
Upper floor – remaining rooms like children's rooms

The builder has now planned a "small and a large air-to-air heat pump" in the utility room.

My plan is rather to switch to an air-to-water heat pump with underfloor heating (should I also install a ventilation system with exhaust air heat recovery at the same time?). But what is sensible for the secondary apartment? Use the air-to-air heat pump of the main apartment and also install underfloor heating there? Here in the forum, I often read about the Panasonic Geisha monoblock. Would that be an option? So many questions...
I am honestly overwhelmed and still at the beginning of sorting out all these topics for the new build. Since a photovoltaic system is mandatory for new builds, it should be sized accordingly.
Then I would rather go for KFW40 without battery and cover the entire roof with panels.

I’m not sure if this information is sufficient to make a meaningful statement.

Thanks everyone.

Best regards,
Ben
U
user-d29
12 Apr 2021 07:23
derBensch schrieb:

I assume the photovoltaic system offered by Bien-Zenker powers both heating systems? It probably isn’t really sufficient.
In any case, during winter you’ll always need to buy electricity when the sun isn’t shining. And that happens quite often ;-)
Oh, and in summer, when the sun is out, you don’t need heating (or just a little for hot water).