ᐅ Which energy standard to build to?

@all

Today, I finally received a written response from the KFW banking group and would like to share it with you.

Thank you for your inquiry.

We are happy to inform you about our product conditions regarding independent experts in the product "Energy-Efficient Construction." These conditions apply to all KfW Efficiency House standards.

The expert must be commissioned for the construction project in an economically independent manner. In addition to providing consulting, planning, and construction supervision for the project, the expert must not have any ownership, partnership, or employment relationship with the construction companies or suppliers involved, nor may they broker deliveries or services.

The following are not covered by this regulation:

- Experts employed by the applicant or seller (e.g., developer) of new residential units
- Experts employed by construction or craft companies (e.g., prefabricated house builders), whose products and services are defined and monitored according to quality assurance.

Kind regards,
KfW

So, not really anything new. I am still waiting for another response; here I am waiting for news from our energy efficiency specialist.

Regards, Bauexperte

As far as that goes, nothing new indeed. Why would anything have changed there?

ChrisNRW schrieb:
I’m responding to the question raised at the start of the thread:

We built a solid house in 2014 and chose the KfW70 standard. The additional effort for this was relatively low; further measures, compared to the energy savings and interest rates, would never have been cost-effective for us. So now we have a well-insulated house at a reasonable price.
For the heating system, we decided against the commonly recommended air-to-water heat pump* and installed a conventional gas heating system. Additionally, we have vacuum tube collectors on the roof as our primary energy source for heating and hot water. They are so efficient that even in winter under cloudy skies, they almost fully cover the water heating demand.
Overall, we chose what I consider the best value for money. Let’s see what our costs will be after the first full year.

________________
*Listing all the reasons against it would go beyond the scope here, and it’s not the main topic anyway.

Oh yes, the beloved theory
The problem with your way of thinking is this:
You built House A and compared it to House B (worse) and House C (better). I’m assuming House A costs about 1000 EUR per year. How do you know what House B and House C would cost? … 800? 1200? As already mentioned, the jump from 100% to 80% efficiency is cheaper than from 70% to 60%. So where is the sweet spot for a homeowner with x residents in town y, with budget z and their habits?
Also, you probably didn’t put the effort into calculating House B the same way you ended up doing for House A (and probably won’t... the prices are already outdated). And who wants to admit they made a mistake in thinking or calculation? What does your energy certificate say, and what will reality show?

For me, it’s hard to follow this, and there are surely some calculation errors involved. Oh yes, and often forgotten are the follow-up costs and interest incurred (for example, easily seen with mechanical ventilation with heat recovery systems).

I think it’s important to consider the options carefully and be cautious with the calculations, because everyone calculates differently!!! The energy consultant uses different numbers than the banker or the seller of the air heat pump, mechanical ventilation system, or whatever. But who calculates correctly? My guess … nobody! Because the basis of the calculation is numbers from the future, and who can really predict that? Once you’ve made the decision, it’s all water under the bridge.

Now, about my decision and reasoning

• The 2014 energy saving ordinance is mandatory, so that’s the baseline.
• We’re not building to KfW standard because I don’t know how I’d refinance in 10 years or what the requirements will be (however they develop). I don’t want to be forced into that framework. I don’t care if I achieve 71% or 69%. We’re financing fully, clear costs, low risk. Yes, it’s more expensive; we can afford it and want to.
• An air heat pump with a hot water tank, because I want to be independent of fossil fuels and keep the flexibility to choose whether my electricity comes from our own photovoltaic system, nuclear, coal, or any power plant. So I can effectively choose my “electricity supplier.” I expect storage options for electricity to become cheaper soon.
• T9 block, 36.5cm (14 inches) without additional insulation. I easily meet the 2014 energy saving ordinance. I don’t have time to calculate every detail, and our supplier offers this block as “standard.” Standard means high demand → better price ... I might still be off. Bad luck.
• Probably without floor insulation (saving about 3000 EUR), but we haven’t decided yet.
• Roof insulation for sure, since the cost-benefit ratio should be very good here. DIY is possible!
• Triple-glazed windows with very good Uw and Ug values that are not significantly more expensive.
• No mechanical ventilation with heat recovery, because the follow-up costs don’t justify the investment. The actual benefit of mechanical ventilation is not "valuable enough" to me.

I don’t know to what extent all this will pay off. Nobody is going to calculate that for me. So I try to use the standard offered on the market. “Older” materials probably won’t be much cheaper! So this is more of a gut feeling.

In the end, the question “which energy standard to build?” can only be answered by yourself because you know your financial situation, your wishes, and your future circumstances best. So inform yourself as well as possible and make your own crystal ball. The more you calculate, the more confident you probably become that your decision was the right one ... I can reassure you, there is no wrong one.