Is insulation worth it beyond the new construction standard?

Concepts like these from the prefabricated house provider Kampa don’t sound bad at first, and partly there are many people in forums who think that you shouldn’t build a house nowadays with a U-value above 0.15.

On the other hand, when you crunch the bare numbers, I don’t quite understand how insulation beyond what is necessary even pays off?

Let’s take a 140-150 sqm house with 1.5 stories. It should have an exterior surface area (external wall) of about 170 sqm (without roof, top-floor ceiling, floor slab, windows, with a relatively high knee wall as we aim for).

A local provider has a U-value of 0.21 in the absolute standard case, Kampa advertises 0.11. According to a U-value calculator, the local provider consumes 16 kWh/m2 per year, and the U-value of 0.11 leads to 7 kWh/m2 per year. Calculated over the area, that is 2,720 kWh or 1,190 kWh. With an air-water heat pump with a seasonal performance factor of 4.1 (yes, these are available for about 4,000 EUR – greetings to the purple forum ) that means 663 kWh_el or 290 kWh_el. So you save 373 kWh through the external wall construction. Variant A: GÜ Massiv Standard and Variant B: Passive House Wall. In hard euros, that is about 93.25 EUR per year or 7.77 EUR monthly installment.

In 20 years, the difference adds up to 1,865 EUR. In 20 years!!!

Of course, you also save with Passive Houses through insulation of the floor slab, roof and better windows, but that also requires separately higher investments.

On the other hand, with a photovoltaic self-consumption system, you can save a lot especially in the transitional seasons (self-generated electricity costs less than half the price of electricity from the grid) or precisely with a KFW40 house you cannot, because then heating is really only needed in the deepest winter, whereas an Energy Saving Ordinance standard house benefits strongly from photovoltaic electricity in the transitional seasons.

The question in the end a little: is it even worth it, or is the Energy Saving Ordinance standard already so strict that the economic efficiency is long since exceeded?

The question is also a bit wood frame prefabricated house vs. solid house. Only with a wood frame prefabricated house can a high insulation value of the exterior facade be achieved with a reasonably bearable external wall thickness (in cm). In my opinion, the only advantage of a wood frame prefabricated house compared to a solid house.

We keep having these discussions. My position is that a Kfw70 standard makes sense for a solid house. It is difficult to compare that with a timber frame house. Or how would you like to quantify the additional costs for the Kampa exterior wall compared to the GÜ solid standard?

you already say it yourself, insulating is no longer financially worthwhile from a relatively early point onwards. the energy regulation is quite strict, which is why house prices have risen more than significantly in recent years. insulating is more for the environment than for the wallet. although that is also nonsense if you own your own wind turbine and operate the air-water heat pump with it (conceivable in the countryside, for example)

Energy cost increases and resale value should perhaps be taken into consideration. imho, the better standard should also be reflected in any potential resale.

And even if the costs triple - you can see from Grim's numbers that it hardly makes any difference in a year. Not without reason did I not go along with the insulation madness to that extent.

Sure, the price increase is a relatively weak argument but the service life of the place is at best not just 20 years and personally I prefer to throw the money to the handyman around the corner rather than into RWE’s throat. Insulation craze is the right term though. In our lifetime we will no longer recoup the additional costs of the higher insulation. For the above reason I decided on a bit more insulation, it was purely an ideological decision.