I am restoring a 15 x 10 ft. greenhouse in north FL--twinwall
polycarbonate on aluminum frame set on a 3-foot wall. GH is attached to
a small concrete block shed. It will have two exhaust fans, ceiling
fan, 4 vents in the wall, possibly a louvered window in the door to the
shed.

Most people seem to use fans in summer, heaters in winter. I have not
read much about air conditioners in greenhouses and wonder why.
Outrageous electric bills? I am considering installing an electric
reverse-cycle air conditioner/heater in the GH wall. Is this
sensible/practical? Thanks.
T-L