ᐅ Attic Renovation with Heating and Cooling Air Conditioning?

Hello,
our planning for the attic conversion and renovation is progressing.
Now we are wondering whether we should indulge in the luxury of an air conditioning system (for heating and cooling) or stick to the traditional method used throughout the rest of the house and heat only with radiators.

Our house receives direct sunlight for at least 12 hours a day.
During last summer’s record heat, the apartment temperature stayed at a minimum of 25°C (77°F) continuously, even though we ventilated in the morning and at night and kept windows and blinds closed once it got warm.

The additional cost for an air conditioning system compared to a conventional heating system would be about 5000 euros.
Thanks to modern technology and the new insulation, electricity costs are expected to remain reasonable.

Has anyone had personal experience with this or is currently considering it?
Thanks in advance.

Regards,
Stephan

Heating with air conditioning seems expensive to me. I would plan both a heating system and an air conditioning system. Our new house will also have air conditioning for the bedrooms since we had around 30°C (86°F) indoors last summer. And there are supposed to be even more hot summers to come.