ᐅ Is it worth paying extra for KFW55 energy standard, or not?

Hello community!

We are building with high thermal insulating thermobricks, but only to the Energy Saving Ordinance standard. So far, no KfW55 level, more like KfW70 if you will. The extra cost for better insulation is 7,800€ plus either a photovoltaic system or 4 decentralized ventilation units.
(We don’t have a central controlled ventilation system installed. That’s a separate topic. My wife doesn’t want it and money is tight.)
You have to subtract a 5,000€ grant but add back about 1,500€ for the KfW certification. The subsidized interest rates don’t really offer any advantage or are even worse than regular financing options.
In the end, there are roughly 8,000€ additional costs that you would have to save with reduced energy consumption.
1. Does this take forever? What do you think?

KfW55 will become mandatory by law in 2021. Soon our house would therefore be energy-wise outdated and probably worth less. But KfW70 was still subsidized two years ago and is actually quite good already, right?
2. Even if it might not be economically worthwhile today, would you still opt for better insulation?

3. Can an air-to-water heat pump be operated without issues in a house built to Energy Saving Ordinance standards, or would it then become a major electricity consumer?

Heat pumps are also feasible in KfW 70 buildings. Achieving KfW 55 requires extra insulation and more expensive technology. However, this does not improve the house itself. Don’t bother with it. Save that money and invest it in mechanical ventilation. If your wife doesn’t want a full ventilation system, you can install a humidity-controlled exhaust fan by Helios on each floor, ideally placed in a bathroom. Additionally, install a controlled air supply ventilation unit in each window. This should be affordable. New houses are simply too airtight to avoid doing something about ventilation. Karsten

We decided on a central controlled residential ventilation system, and with the interest rates for 20-year fixed loans from KFW at a record low, we went for KFW 55 efficiency—it turned out to be cost-effective. Today, I would build according to the Energy Saving Ordinance.
There isn’t a huge difference between KFW 55 and the Energy Saving Ordinance even now; the monthly savings are not that significant. However, I would pay attention to the ventilation options.

3. It will probably consume a bit more energy, but not significantly more. Why do you want to use an air-to-water heat pump?

Thanks for the answers so far.

Why do we want an air-to-water heat pump?

I hadn’t questioned it until now because we want a KfW55 standard, and instead of radiators, underfloor heating, and air-to-water heat pumps are so common and well-promoted.
The base price would otherwise include a condensing gas boiler.
The additional cost for the air-to-water heat pump is €6900 compared to the gas boiler.

I always find the additional charge quite cheeky, both for KfW55 and for the air-to-water heat pump.

For KfW55, a better building envelope is required. This means better insulation. Here, only the material costs can increase. The labor is already there anyway, except in the case of monolithic construction. Regardless, the general contractor can handle it that way.

With the air-to-water heat pump, I find the surcharge especially cheeky. There is no longer a need for a chimney or a gas connection. Maintenance and chimney sweeping are also eliminated. However, the heating installer must be skilled with heat pumps, otherwise it can get expensive.

Isn’t it possible that just with the air-to-water heat pump and slightly better insulation, KfW55 standards can be met?

Yes, an air-to-water heat pump and insulation can be sufficient. Ventilation is not mandatory unless proof is required according to the KfW reference method.