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

Hi everyone,

We are currently planning our single-family home and are receiving different recommendations from various builders regarding construction with or without meeting certain KfW standards. We are planning a solid masonry construction.

We would like to independently review the advantages and disadvantages and are wondering which points should be considered. From our perspective, these are the following:

• Financial considerations
- The repayment subsidy for KfW55 is usually about the same as the additional construction costs, so it balances out more or less
- Energy-efficient construction saves heating costs over time, so building energy-efficient should be cheaper in the long run
- KfW loans currently don’t play a major role, as banks offer similar or even better conditions

• Indoor climate
- Excessive insulation can negatively impact indoor air quality (we only know this from friends, but aren’t sure if this is always the case)

• Land utilization
- Using an external thermal insulation composite system (ETICS) can achieve KfW55 with thinner walls, which on our narrow plot would allow about 10m² (108 sq ft) more living space

• Value retention
- Are there any experience reports regarding the value retention of the different construction methods?

Thank you for your feedback.

The additional insulation measures will not pay off within your lifetime.
If you build only according to the energy-saving regulations (energy saving ordinance / energy performance standards), you have more flexibility and fewer requirements.
A modern building following the energy-saving regulations usually reaches about KFW55 standard—just without the official certification.

Forget the topic of “breathing walls.” Indoor climate has nothing to do with the building’s energy standard.
All modern houses are so airtight that mechanical ventilation is necessary. The best option is a central controlled ventilation system.

Since land and soil do not increase in quantity, prices will continue to rise or at least not decrease in the long term.
Take a look at what is currently for sale. In the worst case, it’s just about the land.
Houses can also be renovated...

If your budget is huge and you want to do some “greenwashing,” build to KFW40+ standard.
If you want to stay flexible and need to calculate costs carefully, build according to the energy-saving regulations (which was a KFW standard a few years ago).
If it’s cost-neutral, you can also build to KFW55 standard.

rick2018 schrieb:

The additional insulation measures will not pay off during your lifetime.
If you build only according to the energy saving regulations, you have more freedom and fewer requirements.
A modern building built according to energy saving regulations usually reaches KFW55 standard, just without a “certificate.”

But then I would take advantage of the KFW subsidy and not do it without the “certificate.” That’s what we are doing as well. The house reaches KFW55 without extra measures; we only have to change the heating compared to the simplest option. It costs much less than the subsidy amount. So why not take it—that ends up being a five-figure sum.

--Lars-- schrieb:

Financial Considerations
- Repayment subsidies for KfW55 are usually about the same amount as the additional construction costs, so this more or less balances out
- Energy-efficient building saves heating costs in the long run, so it should be cheaper over time to build energy-efficient
- KfW loans currently have little relevance, as banks offer similar or even better terms

The KfW repayment subsidy should be clearly higher than the extra investment since KfW 75 is already standard. You won’t see huge additional savings on heating. About 60% of energy consumption depends on the user, 30% on correct heating system design, and only 10% on the energy standard. Between 40 and 75, the energy standard plays a larger role but is still relatively minor.

--Lars-- schrieb:

Indoor Climate
- Too much insulation harms indoor climate (We only know this from friends but are not sure if it’s always the case)

This has nothing to do with insulation. New houses must be built airtight, whether insulated or not (monolithic construction). Indoor climate also depends on ventilation – controlled mechanical ventilation or manual ventilation (if you actually ventilate manually all the time!!!).

--Lars-- schrieb:

Land Use
- KfW55 can be achieved with thinner walls using external insulation composite systems, which on our narrow plot would allow about 10sqm more living space.

10sqm (100 square feet)? I doubt you calculated that correctly. What construction methods are you comparing?

--Lars-- schrieb:

Value Retention
- Are there any experience-based insights regarding the value retention of different construction methods?

Only based on past experience. There is a difference, but it’s not a significant reason today to waste money just for that.

The current standard is KfW 55. Building worse doesn’t make sense since it usually doesn’t save money.

--Lars-- schrieb:

- KfW loans currently have little relevance, as banks offer similar or even better conditions

Starting in July, the funding will also be available as a grant option. This is interesting for everyone who does not want to take out a loan.

--Lars-- schrieb:

Plot utilization
- With an external thermal insulation composite system, KfW55 standard can be achieved through thinner walls, which would allow for about 10sqm (108 sq ft) more living space on our narrow plot.

That surprises me a lot. Assuming a 10x10m (33x33 ft) house, the difference would be approximately 25cm (10 inches) in wall thickness. That should not be the case; realistically, it would be closer to 5cm (2 inches) with comparable systems. Another question is whether you need to fully maximize the building envelope on your plot, or if those few extra centimeters on the outside don’t bother you.

An important point with standards is what you consider fixed. For example, if you would always install photovoltaic panels on the roof (even without funding), then the calculation for the actual additional costs looks completely different. So think about what you would build without subsidies, then get a quote for the extra cost, and decide whether a certain standard is worthwhile. Carefully weigh arguments for and against.

WilderSueden schrieb:

Starting in July, the support will also be available as a grant option. This is interesting for everyone who does not want to take out a loan.

Where can I find details about the pure grant option? Are the grants higher than the repayment grants from the combined programs?