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There are many websites about the building energy regulation / KfW55 / EH55, but many refer to outdated information or do not explain the differences, if there are any.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There are many websites about the building energy regulation / KfW55 / EH55, but many refer to outdated information or do not explain the differences, if there are any.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
V
VielleichtBau27 Dec 2025 20:33Tolentino schrieb:
Well, no, your building envelope must have an H't-value at 70% of (i.e., 30% better than) the reference building to qualify for funding.
That doesn’t automatically mean that your finished building under the Building Energy Act will only meet the reference building values (this depends on the actual execution).
Apparently, the exact verification method (where the entire building had to meet a specific value) no longer exists, but each component must meet the required values individually.
This can sometimes be more expensive than necessary.
You cannot directly convert this to the energy demand, since you also have solar gains, heat from occupancy, etc. That’s why the primary energy demand is decisive for the expected energy consumption.
But of course, all this is a theoretical calculation.
In the end, the heating behavior and how you live in the building matter more than any standardized calculations. Since the Building Energy Act only requires that the H't-value does not exceed the H't-value of the reference house, I assume that many builders and general contractors initially design the house just to barely meet this. Anything better simply costs more.
What interests me regarding the final energy demand is this: The transmission heat loss H't-value multiplied by the temperature difference results in the energy losses. Therefore, I think that to calculate the final heating energy demand (excluding solar gains, water heating, etc.), you simply multiply the H't-value by the temperature difference-time profile. So, a significant reduction of the H't-value compared to the minimum requirement in the Building Energy Act should have a strong effect, or am I mistaken here?
No. You are focusing too much on a detail that is practically negligible:
1. Even with KfW 70 (This was under the Building Energy Act 2020 → primary energy demand at 0.7 of the reference building), I achieve 80% of the Building Energy Act reference building in terms of heat transmission loss.
That means, if you want to reach 0.55 for primary energy demand, you already have to do better, and then you automatically achieve a better value than the reference building.
Only if you say it should be KfW 55 eligible will the builder plan with corresponding buffers and must ensure that every component has a maximum of 0.7 according to the component list in Appendix 1.
They will charge you accordingly for that. Then you can be sure that you won’t have any heat transmission loss above 0.75 anywhere.
But this hardly changes your energy consumption (which is even less than the primary energy demand).
Another example: The transmission heat loss only matters for the heating load. The heating load is about two-thirds of the total energy demand (roughly one-third is for hot water).
So, to take my own consumption as an example: Extrapolated, we have 3300 kWh of electricity consumption for heating and hot water. Let’s say one-third is for hot water (I can’t read that exactly with my setup).
That leaves 2200 kWh for heating (yes, it’s a lot, I know; unfortunately, my wife is the type who keeps ventilating until -5°C).
Now let’s simply assume the percentages of the reference building run linearly and could be transferred 1:1 to heating energy (just for modeling purposes), then your Building Energy Act 2023 construction would already be 21% more efficient than my Building Energy Act 2020 one.
That means 1738 kWh.
2200 – 1738 = 462 * 0.39 = 180 EUR
Over 40 years, the price for your house can therefore be 7200 EUR higher than mine (just for better insulation).
The difference between the Building Energy Act 2023 and KfW 55 eligibility is probably even smaller.
This is just a rough calculation on paper.
And as I said, in practice, a full bath once a week can make more of a difference.
The average premium for KfW eligibility is probably higher, but sometimes you get lucky.
It would actually be better, as other contributors have already mentioned, to choose a provider who offers that standard as their minimum.
You’re better off investing your time and energy in other issues that you will definitely face in this life project and where your efforts will be more fruitful.
1. Even with KfW 70 (This was under the Building Energy Act 2020 → primary energy demand at 0.7 of the reference building), I achieve 80% of the Building Energy Act reference building in terms of heat transmission loss.
That means, if you want to reach 0.55 for primary energy demand, you already have to do better, and then you automatically achieve a better value than the reference building.
Only if you say it should be KfW 55 eligible will the builder plan with corresponding buffers and must ensure that every component has a maximum of 0.7 according to the component list in Appendix 1.
They will charge you accordingly for that. Then you can be sure that you won’t have any heat transmission loss above 0.75 anywhere.
But this hardly changes your energy consumption (which is even less than the primary energy demand).
Another example: The transmission heat loss only matters for the heating load. The heating load is about two-thirds of the total energy demand (roughly one-third is for hot water).
So, to take my own consumption as an example: Extrapolated, we have 3300 kWh of electricity consumption for heating and hot water. Let’s say one-third is for hot water (I can’t read that exactly with my setup).
That leaves 2200 kWh for heating (yes, it’s a lot, I know; unfortunately, my wife is the type who keeps ventilating until -5°C).
Now let’s simply assume the percentages of the reference building run linearly and could be transferred 1:1 to heating energy (just for modeling purposes), then your Building Energy Act 2023 construction would already be 21% more efficient than my Building Energy Act 2020 one.
That means 1738 kWh.
2200 – 1738 = 462 * 0.39 = 180 EUR
Over 40 years, the price for your house can therefore be 7200 EUR higher than mine (just for better insulation).
The difference between the Building Energy Act 2023 and KfW 55 eligibility is probably even smaller.
This is just a rough calculation on paper.
And as I said, in practice, a full bath once a week can make more of a difference.
The average premium for KfW eligibility is probably higher, but sometimes you get lucky.
It would actually be better, as other contributors have already mentioned, to choose a provider who offers that standard as their minimum.
You’re better off investing your time and energy in other issues that you will definitely face in this life project and where your efforts will be more fruitful.
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