Energetic House Renovation: Is it sensible to involve an architect?

We want to energetically renovate a house from the 70s. This house is in its original condition. It has a full floor, a basement, and a converted attic. The living area is about 180 m2. The basement is another 120 m2. The basement is to be partially converted into a granny flat (some rooms are already partially finished for living).

We want to renovate to KfW 70 EE standard (KfW 261) and we already have a preliminary acceptance (BzA) for this. We need a building permit for the granny flat. We only want to make a few changes to the floor plan. We do not need an architect for the interior work. [...]
The focus here is on the energy measures: window replacement, roof, facade, basement floor, and perimeter insulation.
It is very important to us to have expertise on the construction site, meaning an expert who oversees that the work is carried out correctly. We cannot assess this ourselves. But does this necessarily have to be an architect?

When building with existing structures, you need the architect almost more than when building new – especially to stay within budget. The best construction manager (without quotation marks) is the architect who "conceived" the renovation. However, I am happy to advise on which specialist you need for what.

I have read the house building guide from ant11, which is, however, specifically focused on house building. According to this, it would of course be easiest to commission all service phases. Now I have contacted an architect in this regard (I am aware that more than one should be contacted), and was quoted €60,000. I find that extremely expensive. Therefore, I wonder if it is worth the money?
At which points should one definitely plan for an architect and why? Where can one possibly do without one? What would be a good price/performance solution?
What is your general recommendation for renovations?

There can be no general recommendation, as you should have recognized when reading the house building roadmap: that it cannot or does not want to be a "one size fits all scheme F". That is why, in addition to the basic series, the (further continued) "Reloaded" episodes exist. Also, among other things, at the top of the page, you can find where to contact the 11th member personally (please don’t turn him into an ant!), if only because the renovation guide is still pending. The "most expensive" service phase (5) is simultaneously also the most cost-effective. I am happy to find the right combination of architect, builder, and building surveyor for you. Just get in touch (and don’t forget, you can never do this too early – unfortunately, I have waiting times like a specialist doctor; I don’t know the colleagues’ calendars but don’t expect much difference, as their economic situation is the same).

It has already been mentioned here that insufficient ceiling height can be an obstacle to converting storage space into living space – I hope your financing does not rely on this rental income.

There are already several threads on the subject of an [Einliegerwohnung im Keller]. If it is not a basement apartment on a slope with exposed terrace doors, it’s nonsense. Who should live there? Mrs. Mole? A basement is not living space for good reason. It will not become living space just by painting the walls and reclassifying it.

There are already several threads on the topic of a basement granny flat. If it is not a basement apartment on a hillside with exposed terrace doors, that is nonsense. Who should live there? Mrs. Mole? A basement is not living space for good reason. It will not become living space through paint on the walls and reclassification.

I am happy to answer the questions: The house is located on a hillside plot, so one half consists of classic basement rooms and the other half of partially residentially developed rooms. There is a ground-level entrance as well as normally sized windows. We are not financially dependent on renting it out. We are creating the second living unit more for subsidy reasons. The gender of potential tenants does not matter, nor does the last name. Mrs. Mole would therefore be warmly welcome.

We are building the second residential unit mainly for funding reasons.

You should calculate whether it is really worth it. This is rarely the case - rather renovate it "privately" and use it as a residential-like area for yourself or the children.

You should calculate whether it really pays off. It is rarely the case - rather expand "privately" and use it as a living space-like area for yourself or the children.

Why do you think it does not pay off? Double low-interest loan, double repayment subsidy, and additionally more living space in the house, which is directly reflected in the resale value. Let's say the granny flat costs us an extra €100,000 (the number is made up). Then I have created 70 m2 of living space for just €1,430/m2, and that does not even factor in the above-mentioned advantages.

Let's say the granny flat costs us an extra €100,000 (the number is pulled out of thin air). Then I have created 70 m2 of living space for just €1,430/m2 and the aforementioned advantages are not even factored in yet.

And that's exactly what you have to calculate, whether it is worth it or if you "only" build normally. Or whether renting out is profitable. If you don't rent out, you don't need proper living space.