These are some seriously expensive houses. If net zero is about reducing total cost of ownership, these don&#x27;t cut the mustard. I personally would be more interested in factory-built modular housing with the minimum of fancy gizmos - just the basics of high R-value insulation, good seals, appropriate placement of windows, and energy efficient HVAC. If net-zero is about reducing our carbon footprint, then I&#x27;d be buying a used house and doing some light renovations to make it more energy efficient.<p>You can get 80% of the way there by blowing foam into the  walls, sealing leaks, investing in good windows, and making sure your HVAC system is appropriately sized and used only when needed.<p>Disclaimer: I used to work on this: <a href="http:&#x2F;&#x2F;ecomod.unm.edu&#x2F;" rel="nofollow">http:&#x2F;&#x2F;ecomod.unm.edu&#x2F;</a> so I might be somewhat cynical.