How to achieve KfW40? Energy technology / Economic efficiency

2020-12-29 22:25:19

Dear experts,
we have just been very lucky and were able to buy the last plot in the place of friends. Now we are building a small house for our parents with a trusted general contractor who already built our house 10 years ago. Unfortunately, we are (still) laypersons and therefore ask you (almost) at the very beginning of our planning for your opinion, especially regarding the energy technology.

Briefly about the house, plot, and residents:

Regarding our questions:

Please excuse the many questions and the lack of knowledge. We would really appreciate your answers so that we at least do not make any major mistakes.

Kind regards

2020-12-29 22:41:51

Ultimately, any form of insulation helps—insulation of the floor slab, roof insulation, window quality, and especially the issue of thermal bridges.
Generally, no one can tell you that. I would first specify what I want anyway (e.g., floor slab insulation, photovoltaic partially creditable, controlled residential ventilation... or whatever it is for you that should definitely be included for comfort reasons).
I have just been through it myself and therefore believe that you should look closely when searching for the right energy consultant, as there are considerable differences there as well.
You could, for example, start with a consultation appointment at the consumer advice center; I was actually surprised by their competence even in partial areas, although it can also be a matter of luck or bad luck whom you get.
I would definitely choose one who can carry out all services themselves, including calculating thermal bridges. My impression was that some consultants do this rather rudimentarily.
Once it has been calculated, they can then "play" with it a bit—a little less insulation here, but different windows there, etc.
For me, the priority would always be first what I want anyway. The outer shell, i.e., the type of stone used, is also a notable factor in this calculation.
With photovoltaic modules, it's like with cars... there is everything; initially, I would ask the electrician what they offer. Sense/nonsense of a storage system... never-ending story. That also partly depends on the life of the residents; with Kfw40Plus, you have to have one anyway.
Generally, I would not only look at the calculation in all this but also at what I want, such as storage systems.

2020-12-29 22:42:33

We would like to achieve the kfw40 standard. What measures do you suggest/are absolutely necessary?

ETICS made of Resol.

Experts for the installation of photovoltaic systems in the Ruhr area/Sauerland recommend?

Clensolar. But they come from eastern Germany. Great company with good prices.

Does a storage system make sense?

If you want 40 anyway, then go for 40+. Otherwise, the storage is rather not worth it. But take the subsidy already for a wallbox.

2020-12-29 22:55:07

Ultimately, any form of insulation helps, insulation of the floor slab, roof insulation, window quality, especially the topic of thermal bridges. Generally, no one can tell you this. I would first specify what I want anyway (e.g. insulation of the floor slab, photovoltaic partially credited, controlled residential ventilation... or whatever it is for you that should definitely be included for comfort reasons. I just went through it and therefore believe that you should look closely when searching for the right energy consultant, because there are significant differences there as well. You could start, for example, with a consultation appointment at the consumer advice center; I was quite surprised by their competence even in partial areas, although it can also be luck or bad luck whom you get. I would definitely choose one who can perform all services themselves, including calculating thermal bridges. My impression was that some consultants do this rather rudimentarily. Once it is calculated, he can “play” with it a bit, a little less insulation here, but other windows there, etc. My priority would always be first what I want anyway. The building envelope, i.e. the type of stone used, is also a significant factor in this calculation. With photovoltaic modules, it's like with cars... there is everything; initially, I would ask the electrician what he offers. The sense/nonsense of a storage system... never-ending story. That also partly depends on the lifestyle of the residents; with Kfw40Plus, you need one anyway. Generally, I would not ONLY look at the calculation in all this but also at what I want, for example, also storage.

2020-12-29 22:56:07

Thank you all for the quick replies. Wow, that was fast. It really helps a lot!

Resol-WDVS is very expensive, though, isn't it?

2020-12-29 23:27:37

Resol-WDVS is quite expensive, isn’t it?

It’s relative. You can achieve “thin” walls with it. And at the same time, excellent insulation.
Example: My 60s old building only needs 12 cm insulation for KFW 55. This saves me from enlarging the eaves. Overall, it is therefore cheaper than using normal insulation material and simultaneously hiring the roofer.

Similar topics
06.04.2016	Financing for 15 or 20 years? Photovoltaics via KFW?	10
11.09.2016	Base plate - construction/insulation etc. - experiences please!	10
13.07.2016	Photovoltaic storage - experiences? Tips?	17
13.09.2016	Insulation under the floor slab EPS or XPS?	12
10.10.2017	New photovoltaic system with storage in single-family house - experiences	39
27.11.2016	Double insulation below and above the floor slab?	10
17.05.2017	Photovoltaics initially without storage	54
05.03.2018	Photovoltaic planning - possible retrofitting of battery storage	13
26.02.2018	Insulation under reinforced concrete floor slab KFW55	20
01.07.2019	KFW 55 - Insulation under the floor slab	37
02.02.2020	Insulation under the floor slab - Is it sensible? Experiences	39
05.05.2020	Photovoltaic system + storage with or without cloud tariff	13
08.05.2020	Heat pump + photovoltaic system with or without storage	11
09.11.2020	Lower Saxony subsidizes photovoltaic storage	20
10.02.2021	Is KfW40+ possible even if photovoltaic and controlled residential ventilation were already required for KfW40?	15
20.02.2021	Exterior wall for KFW 40 (+) with or without ETICS?	86
07.11.2021	Newly built single-family house - gas or air heat pump + photovoltaics + storage?	169
19.07.2021	Insulation of the upper floor ceiling. Checked by energy consultant?	12
14.06.2022	KfW BEG funding stopped 261, 262, 263, 264, 461, 463, 464	1239
29.04.2025	Insulation of the ground slab in the basement with thermal stone	12

How to achieve KfW40? Energy technology / Economic efficiency

Sascha1977

pagoni2020

nordanney

Sascha1977

Sascha1977

nordanney