How is the transition to the summer garden properly insulated?

We are currently having a house built with an attached summer garden. A summer garden is an unheated conservatory. Now, an acquaintance of ours, who is a master mason himself and runs a construction company, looked at the whole thing in the shell construction phase and is surprised that the base slab of the summer garden adjoins the base slab of the house without insulation. In his opinion, insulation should have been installed here - just like on the other exterior walls - so that frost does not "travel" from the concrete under the summer garden into the living room and we have to heat against it in the living room.

Our builder should have known because we told him that it would be an unheated summer garden.

What do you think about this?

and we have to counterheat in the living room.

No idea how it is done professionally. But "counterheat" is always nicely worded. Whether you end up using 1€ more per month during the winter months because of this "botch job" or not, it doesn't matter. In fact, it has no impact on heating costs.

Why does it have no impact on heating costs?

Why does it have no impact on heating costs?

Because it concerns a tiny area compared to your building envelope. A few centimeters. Obviously, heat is lost through it. But that is marginal. Similar to an attached balcony. You won't notice anything.

Ok. That comforts me. Thank you!