According to Energy Star ( green Homes) all homes in which heating systems are located in unconditioned spaces are grossly ineffecient. It is recomended that the heating appliance be located within the living space and all its piping or ducting as well The worst location of the applaince and ducting is noted, is the attic area above int insulation envelope Their recomended location is in a closet and creating chases within the living space for ducting They claim due to heat loss in un conditioned cooler location 30% to 40% effeciencies are lost never reaching the conditioned living spaces. the leaks and losses inside the living space would create up to 40% more effeciency. One less energy would be needed to produce the heat vollume to compensate for heat losses of losses due to transmission in the ducts. So to be really effecient creative framing needs to be considered. Perhaps ceiling sofits. mechanical closets within the living spaces. I guess I will have to utilize my web server space and scan in this documentations and illustrations so one can see first hand examples. another issue addressed is sealing duct work not tapes but mastic b plus insulation We by wood stoves to augment our heating demands but there are ways to improve what we have Simple design improvements including returns in bedrooms having high low returns and feeds. insulating areas pipes aand duct work. Buttoning up drafts. Lot of things can be done to lessen our fuel usqage.