If the house is an energy disaster, it also needs to be renovated. I recently read something that said you are obliged to adapt it to the Energy Saving Ordinance within the first 2 years after the change of ownership.
What about the electrical system, bathrooms, floors? Are the 100 sqm enough?
Consider whether you can and want to afford the hobby "old property." Maybe a condominium is better – I don't read anything about a love for gardens etc.