The biggest design difference between a zero energy ready home and an Energy Star home is the requirement that all ductwork be 100% inside conditioned space, according to Deltec Homes, which built Asheville, N.C.’s first zero energy ready home. Energy Star rewards such a design, but does not require it.
Moving ductwork inside conditioned space produces energy efficiency gains between 8% and 15% on air conditioning costs, according to one study. A sealed and conditioned attic is a good space to place small, efficient duct runs for a ducted mini-split.
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