Cracks depend on a hundred different factors such as humidity on the day of the pour, ambient temperature currently, ambient temperature on pour day, etc. 

There are also latex topcoats that have active enzymes that will "absorb" ambient odor such as Harmony from Sherwin Williams. 

They’re a little more spendy, but they’ll operate at 100% efficiency down to 5 degrees ambient outdoor temp.

The output from the AC will only drop a percentage of the ambient temperature. 

Some advertise they will increase temperature 20 degrees over ambient at max flow rate. 

Seems if it was in between your ceiling and the roof, the ambient temperature from your unit would keep it from freezing.

Ambient light from the window is 100,000x more bright. 

Today it was -18 and my heat pump had error code p3 which is “ambient temperature too low for compressor to run”.

There is a drop ceiling in the efficiency (and I'm actually looking at next yr adding a layer of drywall or sonopam to the ceiling) however, I explained to them that with the cold and a 120 yr old house that ambient noise can be a little more in the winter. 

Usually about a 20 degree difference from ambient is the best any system can accomplish.