nightjar wrote:
Very difficult to retro-fit, so only really used in new builds. With
those, if you are going to go to all the trouble of fitting the ducting,
air conditioning makes more sense. It is much more energy efficient and
can cool in the summer as well as heat in the winter.

In a new build you can (and indeed have to) insulate such that you don't
need a lot of heat in the first place, which removes the need for a giant
furnace and duct system. Although central air has its advantages - can use
heat pumps to heat and cool. I wonder if we'll start seeing that coming
back for cooling purposes.

Theo