The subsidy, if there is one, is that most KfW loans are interest free for the first 10 years.
I assure you that is a subsidy. Anything given to you of monetary value is a subsidy.
That may be the case. But spending the money has to make some economic sense, subsidy or not. As a home owner, the money saved doesn't make sense for the house I currently own. It would make more sense for new construction, or a complete restoration, OR if I could pass the cost on to some poor renters...and that is the problem.
German law allows land lords to pass on the cost of the KfW loan to their renters, even if the cost of the loan exceeds the cost of energy being saved. So a lot of property owners are using the KfW to subsidise modernising their rentals and then raising the rent accordingly. Then it becomes a rich-person subsidy, paid for by the working poor. I'm not against environmentalism, per se, and I know that global warming is a problem. But the way it's being done in Germany, from energy standards, to the EEG tax on electricity, it winds up benefiting about 3% of the population (those with more than one property) and being a poor tax for everybody else.