Which KFW standard and which technology in new construction

As already mentioned, read through the forum. The same questions come up every 2-3 months.

Gastechnk is mature, heat pumps, on the other hand, are still in their adolescence.

Over 20 years, roughly speaking, you end up with the same costs no matter what you install.

KfW-55 is good. But the energy saving ordinance minimum standard is also sufficient.

What you save in costs upfront is offset by higher consumption, and vice versa.

Ventilation systems are only mandatory in passive houses. However, I do not want to live in a modern house without one. They are simply too tightly constructed due to their design (regardless of whether it is only the Energy Saving Ordinance, 55, 40, or even less).

Either you have the desire and time to ventilate, or you let the technology do it.

I actually often agree with you, nowadays even on the topic of KNX [emoji6] But neither this...

...Heat pumps are still in their adolescence.

nor this...

When calculated over 20 years, roughly the same costs come out no matter what you install.

nor this...

Ventilation systems are only mandatory in passive houses. ... Either you have the desire and time to ventilate, or you let the technology do it.

is unfortunately true. Just read the discussion above. If infiltration volume flow < volume flow for moisture protection (and that is not much), a USER-INDEPENDENT ventilation is REQUIRED. This can be found in DIN 1946-6. If a planner, general contractor, whoever, does not point out that a ventilation concept is missing, they are liable for damages. And as you already say, even the Energy Saving Ordinance 2016 often results in buildings being too airtight for adequate moisture protection. And to believe that manual ventilation is always an alternative is unfortunately wrong. I had to learn that above as well, because I thought the same. But user-independence is crucial for moisture protection. In fact, courts now also seem to see it that ventilating twice a day is unreasonable for working people! I see it differently, but that probably doesn't matter [emoji6]

You can see it however you want... but what I wrote reflects the current conditions.

There are plenty of comparisons and projections regarding the 20 years.

DIN standards are not mandatory but only guidelines, so they can be followed but do not have to be.

And until heat pumps are technically as advanced as established heating options, it will still take years to decades. There is also plenty of experience and information available on this in the rest of the internet and simply in every neighborhood.

P.S. I read the discussion carefully before my initial post.

You can see it however you want... but what I wrote reflects the current conditions.

Well then, I claim the opposite, so who is right now?!

There are enough comparisons and projections regarding the 20 years.

Well then, name some, with sources please. Otherwise, it is what it is, a claim without proof. Unfortunately, it doesn't work like that [emoji4]

DIN standards are not mandatory but only guidelines, so you can comply with them, but you don't have to.

When EU directives refer to DIN standards, they can also become mandatory and gain legal binding force. Just look it up in the MPG and take a look at DIN 13485. So in general, that's not correct, but for the construction industry, maybe it is. But even there, DIN standards are used by courts as the basis for recognized rules of technology to clarify liability issues in disputes, for example. If you then violate a DIN standard here (such as 1946-6) and cannot provide proof of the correctness of your non-standard solution, things look pretty grim. So yes, you don't have to follow them, but being smart is something else. Besides that, your general contractor, architect or whoever is in quite a bit of trouble if he does not point out the lack of a ventilation concept and the implementation of measures for moisture protection (and the three other ventilation levels).

DIN standards therefore do provide manufacturers with legal certainty in product liability matters.

Specifically regarding the ventilation concept, Aunt Google was asked, and Wikipedia provides the following answer.

“The updated DIN 1946-6 standard ensures legal certainty in the crucial areas.

In Germany, it has since been necessary to prove whether sufficient moisture removal is guaranteed even without active window ventilation. If a ventilation concept is created, the resident has a legal obligation to follow it. If the architect or planner does not point out a missing ventilation concept or the non-fulfillment of DIN 1946-6, they are liable in the case of mold damage.

In Austria, this regulation does not explicitly apply. In case of legal proceedings regarding related consequences, the state of the art is referred to, which, due to the absence of an Austrian standard, can be found in the German standard.“

and further

“Nevertheless, legal risks remain for planners and builders even when the standard is complied with. Even with strict adherence to the requirements, it may be that the necessary active window ventilation required to achieve a hygienic indoor climate, which also results from the ventilation concept, is considered unreasonable. For example, courts increasingly consider twice daily shock ventilation as critical or unreasonable for users who work full-time all day.“

Theoretically, it may be so that you don't have to follow it, but you or your construction company/planner run a liability risk in case of disregard. However, it is not prescribed as a law, that is true.

And until heat pumps are technically as advanced as long-established heating options, it will take years to decades.

Well, again a claim eagerly waiting for evidence. [emoji4]

Hello everyone,

for me as an electrician, the DIN VDE 0100 is "law" even though it is only a DIN standard that has NO legal basis BUT, as has already been mentioned here, through the reference to the recognized rules of technology it is practically elevated to law.

Regarding the topic of technology in the house. I think you can't go wrong with a gas heating system + solar thermal.

In my opinion, a ventilation system is mandatory today no matter how and to what standard you build. The risk of getting long-term trouble with mold is simply enormous with today's construction methods. And you can still open the windows despite the ventilation system.

And the fairy tale that the photovoltaic system helps you "heat" with a heat pump is, in my opinion, just that: a "fairy tale". And especially bad are the air/water systems. In winter, I basically heat with electricity and all the wishful thinking of LWWP enthusiasts doesn't help!!

And before any discussions arise here again, I have a 30KW photovoltaic system on the roof and unfortunately, it always produces electricity when I don't need it for heating. Since I drive a plug-in hybrid, I use it to charge my car for about €0.1/kWh. The car needs about 20 kWh/100 km. That means I need €2/100 km.

By the way, I heat with liquefied gas, wood and solar thermal, so I know what I'm talking about (despite a large photovoltaic system on the roof). There is one thing I do, however. The water for the washbasins runs through a continuous flow heater that is suitable for solar thermal. That means the continuous flow heater can handle water up to 70 degrees. In summer, I can wait until the solar thermal system has heated the buffer and don't have to heat with gas. When the buffer is hot, it provides the warm water, and the continuous flow heater does nothing. But if the buffer is cold, the continuous flow heater heats the water up to 45 degrees. If the water comes out of the buffer at 35 degrees, the continuous flow heater helps to raise it to 45 degrees.

Bluntly put: if you want to rebuild an old building, then sure, KfW55 and worse. The guideline is regularly tightened, and your new building is outdated before you even move in. When it’s about every euro, there isn’t much left, but you should be aware that you’re not installing the current state of technology. However, it always depends on who you ask. As soon as your counterpart starts talking about "breathing walls," you should better end the conversation.