ZNE Homes: Comparing Costs With their Conventional Cousins

By Ann V. Edminster, M.Arch., LEED AP The burning question I hear most often about zero-energy (ZE) homes is, “How much does it cost to build one, compared to a conventional home?” Most recently, this has come up in the context of design of the Zero-and-Beyond case study database that NZEC is developing in collaboration with NESEA. Of course, we would love to be able to report on costs. I’ll comment on that eventually, but first I’d like to take a few detours into related topics. Asking the Right Question I believe that “How much [more] does it cost?” is the wrong question to be asking, because it perpetuates an ‘add-more’ mindset, when instead we need to be fostering a mindset of innovation and performance. With that goal, I propose that we ask a different question, one that will go much farther towards advancing the practice of zero-energy building: What changes to design are needed to build zero-energy homes and stay within budget? Whereas the answer to the first question is inevitably some dollar amount, or a percentage, the answers to this question are entirely different. For example: Simplify the building form to save on framing lumber, allow for better air sealing and insulation, enclose more space at lower cost, simplify and downsize the mechanical system, and provide more roof space for solar; or Build a smaller home; or Choose more modest finishes; or All of the above. In fact, our case study research indicates that these are practices that frequently distinguish ZE homes from their garden-variety counterparts, and allow ZE builders to operate profitably while producing superior products. Cost...
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