On Sep 21, 2006, at 5:49 AM, Gerhard Fiedler wrote:

> nowadays all rooms have usually individually
> temperature-controlled heating

Really?  I would think that happens only if you have pure electric
heating, which isn't particularly efficient (nor quick to change
your mind about what temperature you wanted.)  Gas or oil heat
tends to have a central furnace, and it's moderately difficult
to get more than even a single thermostat or "zone."  And it seems
that central air conditioning is more efficient than individual
room air conditioners as well (or is that just an impression.)

Multiple HVAC "zones" are something to think about before
starting construction; we've had suggestions to replace our
single furnace with multiple units to achieve this, but I gather
it would have been a lot easier to plan for that in advance!

BillW
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