ᐅ Annual Heating Costs for KfW55 – KfW70 Energy Efficiency Standards, Heating System Decision

haus1212 schrieb:
How can I carry out a heat demand calculation/heating load calculation?

That should really be left to the MEP engineer and energy consultant. Furthermore, the standard heating load calculation alone does not provide any useful results.

haus1212 schrieb:
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haus1212 schrieb:
Is there an online tool for that?

There isn’t one, because the detailed procedure according to 12831 must be applied. No one will give away valuable expertise for free. Also, some experience is required. A large number of heating load calculations performed by builders or system providers are actually incorrect, especially when controlled ventilation with or without heat recovery is planned.
The preliminary calculation of the actual demand (capacity, energy) for heating and domestic hot water “debunks” many of the myths circulating in this field.

Best regards,

@DerDa: Thanks for your input! A prefab house manufacturer said they only build to KfW55 standard, as anything else doesn’t make sense, while a builder of solid houses said they only go up to KfW70 because the extra costs to reach KfW55 are not worth it. Of course, both say that because they want to sell their houses.
We’re currently struggling with the decision between KfW55 and KfW70. In terms of living comfort, it doesn’t really matter to me, as I don’t really notice the difference. It’s more about the heating costs and how they compare between KfW55 and KfW70…
Does anyone have any insights on this?

Thanks and regards,
Herbert

haus1212 schrieb:
@DerDa: Thanks for your assessment! A prefab house manufacturer said they only build to KfW55 standard, as anything else doesn’t make sense, while a solid masonry house builder said they build up to KfW70 at most, because the extra cost for KfW55 isn’t worth it. Of course, both say this because they want to sell their houses.
Right now, we’re struggling to decide between KfW55 or KfW70. In terms of living comfort, I’m indifferent since I don’t really notice a difference. I’m more concerned about the heating costs and how they differ between KfW55 and KfW70...
Does anyone have any insights on this?

Thanks and regards
Herbert

Good morning,

we seem to be going around in circles here – useful answers have already been provided. If I want data or figures from a manufacturer, they will provide them. That was the case for us. We were able to compare KfW55 and KfW70 numbers for the same house design, naturally with the same heating system. If a company doesn’t provide figures in response to a request and instead uses arguments like those mentioned above, they are out. It’s that simple.

And keep in mind: actual heating costs may look different if, for example, you want 24°C (75°F) in the living room instead of 19°C (66°F), etc.
In that case, you simply need a calculation from a qualified planner, of course for a fee. They only require data about the house (U-values, floor coverings, mechanical ventilation with heat recovery, heating system, target temperatures, location/orientation of the building, windows, number of occupants, and so on) and will calculate it for you. That way, you will get a close estimate of your future heating costs.

But for a general comparison between KfW55 and KfW70, the information from the companies is sufficient.

That’s my opinion.

Regards...

Cascada schrieb:
.... Then you will come quite close to your future heating costs.

Exactly! Modern heating technology requires precise planning anyway if it is to be truly efficient.

Cascada schrieb:
.... But for a general comparison, KfW 55/70 the company data is sufficient.

I see it a bit differently. Often, something is “beautified” that is hardly understandable for laypersons, or it relies solely on energy saving regulations / KfW data.

€uro schrieb:
Exactly! Modern heating technology requires precise planning to be truly efficient. I see it a bit differently. Often, something is "beautified" in a way that is hard for laypeople to understand, or they rely on energy saving regulations/KfW data.

Best regards.

You may be right about that, but a reasonably reliable supplier should be able to provide appropriate data to allow a comparison of KfW70/55 standards.
Hope dies last

Regards...

Cascada schrieb:
You might be right about that,...

This certainly depends on the individual case. However, there is a noticeable trend. Official documents often present overly optimistic calculations, while the actual practice frequently looks very different. For example, a home that is rated as EH 55 on paper suddenly just meets the minimum energy-saving regulation standards, despite significantly higher investment costs.

Cascada schrieb:
...but a reasonably reputable provider should be able to supply relevant data to compare KfW70/55.

Yes, the theoretical evidence on paper. These only allow a theoretical, qualitative comparison. Actual quantities often turn out quite differently in real operation. In such cases, good advice usually becomes very expensive!

Best regards.