KFW grant for renovation of old buildings

Hello everyone,
I have some renovation work coming up soon: - Renewal of the roof (including the roof structure, installation of thermal insulation)
- Renewal of the facade, also with insulation
- Renewal of the heating system (new gas boiler, replacement of radiators and heating pipes)
- retrofitting the windows with roller shutters

Now to my question: does anyone have experience with the KFW grant (not a loan) for individual measures? What requirements do I have to meet and whom do I have to contact to apply for the grant, or do I need an energy consultant? Does each measure have to be applied for individually, since they are carried out by different companies?

I look forward to your help and thank you in advance

If you don't want a loan, have a look around at the [BAFA].

We are using the renovation grant "Energieeffizient Sanieren 430" from KfW. With your project to renew the roof, insulate the exterior facade, install roller shutters, and especially change the heating system, you should easily reach the maximum eligible costs of €50,000. The requirement according to the confirmation letter from KfW is: "To prove the execution, please submit your confirmation after completion via the KfW grant portal. This will be prepared by your energy efficiency expert." But really check with BAFA, as there has been a new program for heating since 1.1.20, and I believe this offers more subsidy than KfW 430, which subsidizes up to €7,500 for eligible costs of €50,000 maximum. Unfortunately, both programs cannot be combined; I specifically asked BAFA about this. Edit: what the energy consultant needs from you are quotes from specialist companies for each trade (even if these are not the companies that ultimately receive the contract).