Our general contractor had very consistent cost data for his conventional homes that were built to the energy code, which made a cost comparison fairly simple: Our house cost 10.1% more to build than a conventional house (after solar tax credits and state incentives, the cost was 7.8% higher than conventional building costs). Excluding the PV and SHW systems, the cost was only 2.2% greater. Also, if you exclude the earth tube, the cost was only 0.7% higher for our efficient, tight, passive-solar house.
This low final cost points out a basic premise of incorporating passive efficiency in new construction: It’s more about how to build than it is about costly new equipment or products. In some cases—such as incorporating advanced framing techniques—framing labor and material costs are actually lower than with standard framed construction. Caulk and spray foam are extremely cheap compared to the cost of not building a tight house. And some of the highest-rated toilets, showerheads, and faucets cost the same or less than their high-consumption counterparts.