How does one correctly balance between the Building Energy Act and KfW 55, 40, and 40 Plus?

Hi everyone,

we are currently planning our single-family house and are receiving different recommendations depending on the house provider regarding construction with or without achieving certain KfW standards. A solid construction is planned.

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

[*]Financial considerations
- Repayment subsidy for KFW55 is generally about as high as the additional construction costs, so this more or less balances out costs
- Energy-efficient construction saves heating costs in the long run, so it should be cheaper to build energy-efficiently in the long term
- KfW loans currently have little relevance, as banks offer similar or even better conditions


[*]Indoor climate
- Too much insulation harms the indoor climate (we only know this from friends, but do not know if this is always the case)


[*]Land utilization
- With a thermal composite system, KfW55 can be achieved through thinner walls, which on our narrow plot would allow about 10sqm more living space.


[*]Value retention
- Are there already experience values regarding the value retention of the different construction methods?

Thank you for your assessment.

The additional insulation measures will not pay off during your lifetime. If you only build according to the Energy Saving Ordinance, you are freer and have fewer requirements. With a modern building according to the Energy Saving Ordinance, you usually achieve KFW55. Just without the "certificate".

Forget the topic of "breathable walls". Indoor climate has nothing to do with the energy standard of the house. All modern houses are so airtight that ventilation is needed. Ideally, a central controlled residential ventilation system.

Since land and soil are not increasing, prices will continue to rise or not decrease in the long term. Take a look at what is currently being sold. In the worst case, it’s only about the land. Houses can also be renovated...

If your budget is huge and you want to engage in "greenwashing", build according to KFW40+. If you want to be more flexible and have to calculate, build according to the Energy Saving Ordinance (which was a KFW standard a few years ago). If it is cost-neutral, you can also build KFW55.

The additional insulation measures will not pay off within your lifetime.
If you only build according to the Energy Saving Ordinance, you are more flexible and have fewer requirements.
With a modern building according to the Energy Saving Ordinance, you usually achieve KFW55. Just without the "certificate".

But then I would also take advantage of the Kfw subsidy and not do it without the "certificate". That's what we do. The house reaches Kfw55 without additional measures, only the heating needs to be changed compared to the simplest version. It costs far less than the subsidy amount. So why not take it, in the end it's a five-figure sum.

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

KfW repayment subsidy should be significantly higher than the additional investment, since KfW 75 is already the standard. You will not achieve large additional savings on heating. Consumption is about 60% dependent on the user, 30% on proper heating planning, and 10% on the energy standard. Between 40 and 75 the energy standard plays a bigger role, but is still relatively small.

Indoor climate - Too much insulation harms the room climate (We only know this from friends, but do not know if this is always the case)

This has nothing to do with insulation. New houses must be built airtight. Regardless of whether with insulation or without (monolithic). Indoor climate also has something to do with ventilation – controlled residential ventilation or manual ventilation (if you really always ventilate manually!!!).

Land use - The KfW55 standard can be achieved through a thermal composite system with thinner walls, which on our narrow plot would allow about 10 sqm more living space.

10 sqm? I doubt that you have calculated this correctly. What kind of construction are you comparing?

Durability of value - Are there already any experience values regarding the durability of value of the different construction methods?

Only based on the past. There is a difference, but no significant reason to burn money today just because of that. The standard is now KfW 55. Building worse is not worthwhile, as you generally do not save money.

- KfW loan currently has no great relevance, as banks offer similar or even better conditions

From July onwards, the funding will also be available as a grant variant. This is interesting for everyone who does not want a loan.

Land use - With the thermal connection system, KfW55 can be achieved through thinner walls, which would allow about 10 sqm more living space on our narrow plot.

That would surprise me a lot now. If we assume a 10x10m house, then the difference would be in the range of about 25cm wall thickness. That should not be the case; realistically, it would be more like 5cm with comparable systems. The other question is whether you have to fully exploit the building window on your plot or whether the few extra centimeters outside do not bother you at all. An important point regarding the standards is what you consider as given. For example, if you would always install photovoltaics 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 funding, then ask what the surcharge would be and decide whether a certain standard is worthwhile. Critically weigh arguments for and against.

From July onwards, the funding will also be available as a grant variant. This is interesting for everyone who does not want a loan.

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