Upgrade from KfW 55 to KfW 40+

what exactly is his contribution supposed to show in this context? I mean the funding is known and it was not about the question of how to achieve 40+. So please help me out here, what do you want to express with that..

The hint is not wrong, since your initial post only included the surcharge for KFW 40 (i.e. more insulation), the photovoltaic system and the storage to achieve KFW 40+. But that is not enough. A controlled residential ventilation system with heat recovery as well as visualization of electricity consumption are also needed. Both are by no means free of charge. I am not a fan of storage systems, quite the opposite, I think the manufacturers deceive consumers across the board with extremely shortened amortization calculations. But still: purchasing the storage system together with the photovoltaic system, if desired, has the significant advantage that VAT can also be applied to it. This is no longer possible afterward, since the tax office assumes that the storage system serves purely private enjoyment and is therefore not attributable to the business. If you consider this, choose a small storage system (i.e. as low investment as possible), then KFW 40+ can quite well work out if the rest of the technology is desired anyway. Then the jump from 55 to 40 is the painful one, because more insulation is necessary. It gets really good if you can assign a storage system to two residential units... then you get double the repayment subsidy. By the way, I don't think the storage system adds value to your house. Unless you only want to live in it for 5 years before selling, the storage system will not survive the sale of your house. So scratch that sentimentality. Either the storage system pays off over its lifetime (a very nasty crystal ball) or it does not. Beyond that, nothing is to be gained.

Photovoltaics - are you building with a heat pump, keyword self-consumption? Then a storage system will not significantly increase self-consumption if the heat pump is well synchronized with the photovoltaic system. In addition, you can also consider the heat pump as storage, since it converts electricity into heat, which is retained for a very long time in your KFW 40 house.

Hello Alex85,
thank you for your reply, I just wanted to explain the KfW 40plus conditions in more detail....
I myself am building a house with 2 apartments in KfW 40 plus in autumn 17 and can then achieve a €30,000 repayment grant. Photovoltaics and controlled residential ventilation are already included in the house price, so I can easily use the upgrade from KfW 40 to 40 plus for the storage...

Then I understand the note now too - presumably I was not clear enough before.
For my KFW 55 house, 11,000 euros are enough to increase the standard to KfW 40, of course with everything necessary. That's how I arrive at my calculation; if there were more costs, the whole consideration would make no sense.

So once again, after offsetting all costs and subsidies, the additional cost from KfW 55 to 40+ is only 5,800 euros!
Unless I have overlooked something essential (and by that I don't mean whether everything was calculated that leads to KfW 40+, because that point is certain).

The question is therefore whether the initial calculation with the subsidies can be done like that at all and whether, in your opinion, it makes sense to go for KfW 40+ at the additional cost of 5,800 euros.

Edit: sure, if I choose a small storage, the additional cost would be even lower in the end...

They say that whoever God gives a position to, He also gives the sense. Old civil servant wisdom. So don’t turn it off. Everything you install can also break. What’s not in there can’t break. I tell you this as the owner of such a blue motion car, while my wife’s Twingo also runs, and very very smoothly without all the electronics and assistances.

You can do the calculation that way. However, it is probably not sensible. I am linking to myself.

You are certainly right, Nordlys, that one should always have the courage to use one's own mind. That is what it ultimately comes down to. But before that, I am currently going through a longer process of forming an opinion. I don’t think it’s that simple to say "this is all nonsense and never worthwhile." Because then there would be widespread agreement on that, and that is not the case. Some people even go beyond that when building passive houses or similar. For me, the crucial question is: from when does something like this make sense?

People can certainly have different opinions on this; I think the truth lies somewhere in between, but for that reason, I also want to hear arguments that I can check for plausibility for myself.

As for all the technology, which is probably the most likely to fail prematurely, it is already completely installed in my KfW 55 house. So we are only talking here about more insulation in walls, floor, roof, and windows, and the storage as the only technical unit for 40+.
This is roughly what the costs consist of.