Concrete ceiling or wooden beam ceiling on garages?

I would not neglect the heat storage of concrete ceilings. Draw heat from the air during the day and ventilate it out again at night.

I would not underestimate the heat storage capacity of concrete ceilings. During the day, draw heat from the air and ventilate it out again at night

This is done by a controlled residential ventilation system with heat recovery without a phase shift dependent on the mass of the ceiling.

These are two different things. The heat recovery helps to get fresh air that is not 30 degrees. But if it is warmer outside than inside, it cannot perform magic. However, it cannot absorb solar gains, nor the heat from occupants and technology in the house.

We also covered the garage with precast concrete elements and made them free of thermal bridges towards the residential building using Isokörbe. Our general contractor wanted about €2,000 more for a pitched roof on the garage. The empty conduits came from the house in the raw ceiling over to the garage at any desired location and were then filled with concrete. I would always do it that way again. For the garage door and lights, boxes are already set in the precast elements at the factory. Everything went like clockwork. The sealing of the flat garage roof was done by a professional, and what we were able to see in between looked very good. If the roof should ever leak, it can be repaired relatively easily without damaging the structure.