ᐅ As for the planning and design of the energy standard and heating concept, beforehand

Hello everyone,

For days (or rather weeks) now, I have been researching the topic of house construction.
First of all, it will be a semi-detached house, and a friend who is an architect is designing it. He will handle all the necessary tasks to submit the plans. Heating concepts, ventilation concepts, etc., are not included here.

The plot is on a slight slope, which is why we are planning a 50 m² (540 sq ft) ground-level granny flat, and the area behind the flat, which connects to the earth, will be used as a basement for heating systems, etc.

Overall, the house will have about 250 m² (2,700 sq ft) of gross floor area and a roof pitch of 45 degrees.

I have already read a lot here in the forum, which has been very helpful, but I think that for the topic of house building, each issue requires its own discussion. 😉

My questions are surely the classic ones:

• Building a house according to the 2016 Energy Saving Ordinance or aiming for KfW 55 standard?
I am currently unsure whether the house will be built according to the 2016 Energy Saving Ordinance or to KfW 55 standard.
Ultimately, this is a question of economic efficiency. But how can I find out exactly?
Do I take my plans to an energy consultant who then calculates this for me?
What costs can be expected for such an energy consultant’s assessment?

I am currently planning to build with Poroton T9 36.5 blocks. As far as I know, it is difficult to achieve KfW 55 with these blocks since the U-value is around 0.23 W/(m²K)?


• Ventilation system
From when is a mechanical ventilation system actually mandatory?


• KfW subsidies
I do not intend to take out a KfW loan. Can I still apply for individual KfW subsidies? Can I apply for individual subsidies myself, or does every subsidy have to be obtained through the bank?

As far as I know, all subsidies must be applied for before starting construction. So, building first and then applying is not possible, right?


• How to heat?
I want to design my heating system primarily for economic efficiency. Being as green or self-sufficient as possible is generally not the top priority. It should simply be the “most economical” system from today’s perspective, with a 15-year outlook (assuming current prices for all necessary resources). A gas connection has already been installed up to the plot. Currently, the new development area is promoting fuel cells (up to €10,000 subsidy). Are there any experiences with this? The system sounds great in theory, with high efficiency, etc.

After much reading here in the forum, I have come to the conclusion that an air source heat pump combined with a small photovoltaic system is currently probably the most economical option?

This is very important to me because I am desperately trying to find the best energy concept for my project and do not know the best way to proceed. For me, the standard according to the 2016 Energy Saving Ordinance is already decent. Maybe one can just save all the effort and simply build with a gas condensing boiler?


Best regards!