In our next home I have designed all of the water and
electric to start on the 2nd floor and for heat-
generating appliances to vent to the 2nd fl so that
the heat could be recovered to pre-heat water.

If I can find or create a fridge and freezer with
external coils then yes, recovery would be awesome!

In the winter (in Fl or sw-GA) the waste heat could
be reused, but in the summer I may need to dump some
of it.

Perhaps the rising heat could be fed into a inverted
funnel and spin a fan at the peak. (Did I mention that
our next house will be a monolithic.com dome?)