Do we still need ductwork in a passive home?
If a passive home requires zero energy in the winter, and if we build it in a way that does not require much cooling in the summer, do we still need to install ductwork? Just thinking of ways to save money.
It is always a good idea to install a backup system, even if you don't use it most of the time.
It also depends on your passive design. Air flow through a home is important to dissipate moisture buildup. If you truly don't need an HVAC system as a backup, maybe think about just installing an air-recycling system to balance the temperature and the stagnant air in the home.
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You should also read Daniel Glickman's Ask A Pro Q&A, "Should we replace our PVC-lined flexible heating ducts with another type of ductwork?"