Just wondering how those of you out there who have included central heating and air in you TF structures (mine is to be 2 stories) have dealt with air conditioning and duct work?

-Christopher

High velocity systems use smaller ductwork then conventinal forced air. Depending on the size of the house you may be able to get away with a chase of about 1' x2'. Another option is a split system, where the air handler is on the second floor and you just run heating and cooling piping up through (again a hi-v type system).

We use 2x8 "spacers" for the second floor.

1x6 T&G, then the 2X8 on top of that, then whatever floor finish you want on the second floor.

Allows for can lighting, duct work, long run grey water pipes etc. Just need a couple of 2X6 vertical walls to get up and down somewhere or a chaise inside of a closet wall works well for duct work.

As Andy suggests high velocity systems are a wonder to work with. The better ones use 2" diameter round flex for air distribution and can easigly be placed in room corners where they are unobtrusive and don't eat wall space. they can be routed directly from you air handler or from a secondary manifold about half a cubic foot in size per floor. They tend to be almost silent, no fan noise and move air at an astonishing 2000cfm. You may find the unicosystem.com website interesting. To go an even greater step forward make you heat exchanger geothermal and get the most energy out for the least energy inserted.
deralte

Check out ductless air-conditioning (heat pump)