ᐅ How do you properly balance the requirements of the Building Energy Act against the standards of KfW 55, 40, and 40 Plus?

Nutshell schrieb:

Exactly, but 25% is not 60%.

That’s not what I meant either.
The heating costs you have can be the same under the Energy Savings Ordinance or in a passive house – last year, I paid only about €250 for district heating in a 1960s apartment outside the scope of the Energy Savings Ordinance (even though energy measures were implemented). But I also have neighbors who pay €1,600 to heat the same apartment. It depends on the user. The building’s energy standard only defines a possible range.

The issue is not about who has higher heating costs and how these are influenced by user behavior, but rather about which standard the house should be designed to meet... and for that, professionals are needed. Houses are too individual for general statements.

At the latest, these details must be provided when submitting the building permit / planning permission application anyway — I recommend involving the energy consultant during the planning phase. H

--Lars-- schrieb:

We would like to independently review the advantages and disadvantages once more and wonder which points should be considered. From our perspective, the following apply:

• Financial considerations
- The repayment subsidy for KfW55 is generally about the same as the additional construction costs, so this is more or less cost-neutral
- Energy-efficient construction saves heating costs in the long run, so it should be cheaper overall to build energy-efficiently
- KfW loans currently have little relevance, as banks offer similar or even better financing conditions.

If the budget allows for a higher standard, you will have lower energy costs in the long term. This is a straightforward amortization calculation.

--Lars-- schrieb:

Indoor climate
- Excessive insulation harms the indoor climate (We only know this from friends but don’t know if this is always the case)

Strong insulation does not inherently harm the indoor climate. The key factors are materials, heating, and ventilation. However, I also have the very personal experience that in many new houses there is a feeling of being sealed inside a plastic container. Conclusion: You decide not only on meeting the standard but also on the implementation. This affects costs regardless of which KfW standard you choose.

--Lars-- schrieb:

Site utilization
- With an external thermal insulation composite system, KfW55 can be achieved with thinner walls, which on our narrow site would allow approximately 10m² (108 sq ft) more living space.

Discuss the specific requirement of "thin walls for more living space" with the architect. Here, I would follow the design. Bigger is not always better or more practical.

--Lars-- schrieb:

Value retention
- Are there any existing experiences regarding the value retention of different construction methods?

The value retention of a house in terms of quality depends less on the KfW standard and more on overall craftsmanship and material quality. The market situation determines the resale value of a house. When supply is high, “features” work particularly well to attract buyers and achieve a good price. When demand is strong, the fact that a house is available for sale is more important than its specific characteristics.

Nutshell schrieb:

Regarding the question of what level of energy efficiency to build for:
If you are young, around 25 -> build as efficiently as possible

If you are around 40 -> it’s less worthwhile, better to invest less and finish paying off loans before retirement.

If you are older… 50 -> don’t bother with additional insulation.

Expensive thermal insulation only pays off over time. I built young and therefore invested in KfW55.
If energy costs triple by retirement, I can handle that. Without KfW55, three times more expensive energy could quickly become six times what it is today. Unbearable.

You assume that this will significantly pay off. But that’s hardly the case. The difference between 45 kWh/sqm (energy saving regulation) and 25 kWh/sqm (KfW40) sounds much bigger than it really is. When you compare that to houses built in the 1970s with heating demands of around 300 kWh, or a typical unrenovated older building with about 160-180 kWh, you realize how good today’s houses really are and that there’s almost no savings left in heating, regardless of the standard. At the same time, in a house built to current energy saving regulations, you have little reason to worry that heating costs will become overwhelming.

And most of us will no longer be heating with gas in retirement. After oil boilers, gas heating will likely be phased out in the coming years for climate protection reasons. Therefore, instead of questionable payback calculations, it makes more sense to ensure the heating system can work efficiently with a heat pump or similar technology. Choosing radiators instead of underfloor heating to save costs will probably backfire within 15 years.

Hangman schrieb:

If I did anything right in our project—and I mean really right—it was deciding to involve a competent energy consultant (in our case, an engineering firm / expert) early on.

Simple question, but how did you pick the right person without knowing much beforehand? Did you just trust your building partner? I looked at the four-page list of energy efficiency experts in our area and kept going back and forth between a "solid tradesperson" and "maybe a fancy architect" before deciding.

Sometimes it is easier to explain what went well in hindsight than to predict it in advance. We all build more or less as amateurs and make decisions based on relative uncertainty. We have found it effective to evaluate people more than prices and to place trust in them. However, even with this approach, regardless of our experience, things can still go terribly wrong. Others rely on watertight contracts and credit them for everything going smoothly. For some, this method has failed miserably.
We are all the authors of our own experience reports and construct success stories and cause-and-effect relationships backwards.
Building a home always involves risks. The responsibility for decisions lies with the homeowners. Freedom always includes accepting the consequences of one’s own actions—regardless of their predictability or any questions of “fault.”