ᐅ Building Energy Act vs. KfW55 vs. EH55: Simple Explanation of the Differences in New Construction (As of 2025)
Created on: 26 Dec 2025 03:33
V
VielleichtBau
Hello everyone,
I have been reading this forum for a while, and now we might start building. We have already had some discussions with a few mostly regional general contractors in Middle Franconia / Bavaria.
Some of them asked whether we want an EH55 or KfW55 house, or just to comply with the building energy regulation. I am confused about this. Until now, I thought that every new build must comply with the building energy regulation, which currently states that a single-family house may only have a primary energy consumption of 55% compared to a reference building. I assumed that this corresponds exactly to EH55 or KfW55.
There are many websites about the building energy regulation / KfW55 / EH55, but many refer to outdated information or do not explain the differences, if there are any.
Could you please clarify for me what the difference is as of December 2025 between these three types: minimum standard house according to the building energy regulation versus efficiency house 55 according to KfW55?
Thank you.
VielleichtBau
I have been reading this forum for a while, and now we might start building. We have already had some discussions with a few mostly regional general contractors in Middle Franconia / Bavaria.
Some of them asked whether we want an EH55 or KfW55 house, or just to comply with the building energy regulation. I am confused about this. Until now, I thought that every new build must comply with the building energy regulation, which currently states that a single-family house may only have a primary energy consumption of 55% compared to a reference building. I assumed that this corresponds exactly to EH55 or KfW55.
There are many websites about the building energy regulation / KfW55 / EH55, but many refer to outdated information or do not explain the differences, if there are any.
Could you please clarify for me what the difference is as of December 2025 between these three types: minimum standard house according to the building energy regulation versus efficiency house 55 according to KfW55?
Thank you.
VielleichtBau
MachsSelbst schrieb:
And a centralized ventilation system isn’t free... it uses electricity... You can practically ignore the electricity consumption, as I have observed after several years of using a controlled residential ventilation system. For many users, the added value is significantly higher due to improved air quality and prevention of mold, etc.
If the budget allows, I would always go for maximum insulation, whether or not I receive a KfW40 subsidy. It just seems sensible and reasonable to use less energy from the start.
V
VielleichtBau26 Dec 2025 13:09Hello,
Thank you for the many responses. My main goal is to technically understand whether there are different requirements regarding the Building Energy Act (current status in 2025), EH 55, and KfW 55.
What confuses me is that some general contractors have asked whether it should be EH 55 or KfW 55, saying that these are not the same as the Building Energy Act. I heard this several times, even after I mentioned that the Building Energy Act currently requires a minimum standard of 55% of the reference house.
I wonder what the technical differences are in the requirements for these three types?
Can someone confirm the comment by @Tolentino about transmission heat loss being different between EH 55 and the Building Energy Act?
Oh, and please no debates about insulation, cost-effectiveness, or controlled ventilation, etc. 😉 I will look into those once I understand the above differences first.
Thank you for the many responses. My main goal is to technically understand whether there are different requirements regarding the Building Energy Act (current status in 2025), EH 55, and KfW 55.
What confuses me is that some general contractors have asked whether it should be EH 55 or KfW 55, saying that these are not the same as the Building Energy Act. I heard this several times, even after I mentioned that the Building Energy Act currently requires a minimum standard of 55% of the reference house.
I wonder what the technical differences are in the requirements for these three types?
Can someone confirm the comment by @Tolentino about transmission heat loss being different between EH 55 and the Building Energy Act?
Oh, and please no debates about insulation, cost-effectiveness, or controlled ventilation, etc. 😉 I will look into those once I understand the above differences first.
My assumption is based on:
§ 16 of the Building Energy Act
It states: [...] "The transmission heat loss does not exceed 1.0 times the corresponding value of the reference building according to § 15 paragraph 1"
As well as the "Annex to Information Sheet Credit No. 297/298/498 Efficiency House 55 - Residential Buildings - Technical Minimum Requirements"
It states:
"The following minimum requirements must be met: Efficiency House 55 EH 55 QP as a percentage of QP REF 55% H’T as a percentage of H’T REF 70%"
So according to the Building Energy Act, 1.0 of the reference building, according to the KfW funding condition: 0.7 (=70%) of the reference building (H'T REF) according to Annex 1 of the Building Energy Act.
H'T means transmission heat loss.
§ 16 of the Building Energy Act
It states: [...] "The transmission heat loss does not exceed 1.0 times the corresponding value of the reference building according to § 15 paragraph 1"
As well as the "Annex to Information Sheet Credit No. 297/298/498 Efficiency House 55 - Residential Buildings - Technical Minimum Requirements"
It states:
"The following minimum requirements must be met: Efficiency House 55 EH 55 QP as a percentage of QP REF 55% H’T as a percentage of H’T REF 70%"
So according to the Building Energy Act, 1.0 of the reference building, according to the KfW funding condition: 0.7 (=70%) of the reference building (H'T REF) according to Annex 1 of the Building Energy Act.
H'T means transmission heat loss.
N
nordanney26 Dec 2025 16:14VielleichtBau schrieb:
Are there different requirements regarding the Building Energy Act (current status in 2025), EH 55, and KfW 55? So, once again from me:
There is only the Building Energy Act (55% primary energy consumption) and EH 55 (as specified by KfW). EH 55 has the same primary energy consumption as the Building Energy Act, but the Ht value is slightly stricter (better insulation required).
So there are only two standards – one according to the law and one for potential funding (the budget will only last days or weeks, not months – my experience from working in a bank).
VielleichtBau schrieb:
I wonder what the technical difference is regarding the requirements for the three types? See above. EH 55 has a marginally better building envelope. That’s about it.
VielleichtBau schrieb:
Oh, and please no debate about insulation, cost-effectiveness, controlled residential ventilation, etc. 😉
I’ll look into that once I understand the difference mentioned above. Practically, there is almost no difference. The Building Energy Act is the absolute minimum and is no longer quite up to date. Anyone offering only the Building Energy Act standard is likely to be the "low-cost provider" trying to offer you the bare minimum to make the house look inexpensive. Which then usually becomes more expensive again due to requests or according to the building specification “provided by the client.”
V
VielleichtBau27 Dec 2025 14:10I have now examined the building energy law in detail. Overall, this would mean that there is "only" a difference in the transmission heat loss.
For the EH 55, this would need to be 70% of the value required by the building energy law. I would assume that the necessary heating energy is also reduced by about 70%. Is that correct? That would be quite significant.
For the EH 55, this would need to be 70% of the value required by the building energy law. I would assume that the necessary heating energy is also reduced by about 70%. Is that correct? That would be quite significant.
Well, no, your building envelope must have a heat transfer coefficient (H't-value) at 70% of the reference building (about 30% better) to qualify for the subsidy.
This does not automatically mean that your finished building energy code construction will only meet the reference building values (that depends on the specific execution).
Apparently, the exact verification method no longer exists (where the entire building had to meet a certain value); instead, each component must individually meet the required values.
This can sometimes be more expensive than necessary.
You cannot directly convert this to energy demand because you also have solar gains, waste heat from occupancy, etc. That’s why primary energy demand is decisive for the expected energy consumption.
But of course, all of this is a theoretical calculation.
In the end, heating behavior and how people live in the building matter more than any standardized calculations.
This does not automatically mean that your finished building energy code construction will only meet the reference building values (that depends on the specific execution).
Apparently, the exact verification method no longer exists (where the entire building had to meet a certain value); instead, each component must individually meet the required values.
This can sometimes be more expensive than necessary.
You cannot directly convert this to energy demand because you also have solar gains, waste heat from occupancy, etc. That’s why primary energy demand is decisive for the expected energy consumption.
But of course, all of this is a theoretical calculation.
In the end, heating behavior and how people live in the building matter more than any standardized calculations.
Similar topics