“Apparently the A/C in his office is unicorny magically removing covid”
And hospitals everywhere?
Yes, they have some zones that use 100% outside air, where the air is conditioned and flows though only once and is exhausted to the outside using lots of energy.
Typically about 15% outside air is continuously added and exhausted.
In most single-family homes the air change is determined by what leaks out.
Maybe not “lots”. There are some pretty efficient air-to-air heat exchangers, if it is with the fixed cost price.
I remember when highly efficient housing was the rage, and they realized we would kill people with gassing from various products, because we were not exchanging enough air. So they started putting air-to-air exchangers in the houses, to bring in fresh air.
Technically, the process of heat transfer is energy-free; the cost is in making it efficient enough to be useful.