ᐅ Is it worth choosing KfW55 instead of KfW70 with an additional cost?

At the moment, we are planning a KfW70 house (controlled residential ventilation with heat recovery and an air-to-water heat pump). For an additional cost of about €8,000, we could upgrade to KfW55. This means more insulation would be required. As far as I know, the basement, the ground loop, and the house itself would need thicker insulation, and some work on the windows might also be necessary.

If I take advantage of the KfW loan, the interest rate for KfW70 is 1.4%, and for KfW50 it is 0.75% plus a €2,500 repayment subsidy. When you calculate the interest and the bonus, I would save almost €5,500 in interest, €3,000, and receive the €2,500 subsidy.

Now I wonder whether this is still worth it or not. Clearly, the house with KfW55 should consume less energy over time, but can this really be calculated so simply to justify the investment? Is it reasonable to say the house would have around €50 less heating costs per month?

What would you do?

Without specific quotes, it will be difficult for you to answer that...

Which specific details are you referring to? The general question is whether improved insulation of the house noticeably reduces the primary energy demand, so that it is reflected in the running costs.

We currently have a calculated annual primary energy demand of 46 kWh/m² (4.3 kWh/ft²). KfW55 standard is around 39 kWh/m² (3.6 kWh/ft²). To achieve that, I would need about €8,000. I can calculate the annual consumption myself, but it is often said that these calculations are somewhat optimistic. So the question is whether the effort and cost are worth it or not.

Watcher78 schrieb:
We are currently planning a KfW70 house (controlled residential ventilation with heat recovery and an air-to-water heat pump). For an additional cost of about €8000, we could upgrade to KfW55. This means more insulation would be required. As far as I know, the basement, the ground loop, and the house itself would need thicker insulation, and the windows would probably have to be upgraded as well.
If I take out the KfW loan, the interest rate for KfW70 is 1.4% and for KfW50 it is 0.75% plus a €2500 repayment grant. Comparing the interest and the bonus, I would save nearly €5500 in interest, €3000, and receive the €2500 grant.
Now I wonder if it’s still worth it or not. Of course, the house should consume less energy in the long run with KfW55, but can you really calculate it that easily to see if it pays off? Can you simply say that the house will have €50 less heating costs per month?

At least regarding heating cost savings, I have to temper your expectations.
For an average house, your monthly heating costs will likely be around €50 (about $55), not a €50 saving per month. You might save €5-15 (about $5-16) per month—that’s not very significant.

Completely unaccounted for, since it’s hard to quantify, is the value of the house itself. Which house would you rather buy today (a 20-year-old property)—one that was already built very energy-efficiently back then, or a drafty house? That’s also how people will think about YOUR house in 20 years.

We decided against the additional effort and cost for KfW55 (in 2013). Formally, our house meets KfW70 standards, but with better windows it performs significantly better. Heating consumption including hot water (in the first year, geothermal) was about €55 (about $60) per month for 300sqm (about 3200 sq ft) of heated area and five people. What more savings should I expect from that?

Exactly the 8,000,000 €... if that is the additional cost, it won’t pay off from an energy cost perspective.
The question is what you get in return... for example, if there is a mechanical ventilation system with heat recovery, you will also gain increased comfort, which you need to quantify for yourself.

The additional cost is €2,500 when I offset the interest and the €2,500 bonus. The expense is roughly €8,000 minus €3,000 interest savings compared to the interest for KfW70, minus the €2,500 KfW55 bonus, which equals about €2,500. Therefore, the question is whether it makes sense to invest the money or to leave everything as it is.