There are two possible routes home builders are apt to take as they try to engineer their new houses to produce as much or more energy as they consume: one, is through the envelope, and the other is through the systems.
And there's just one way--when you blend building materials that perform the best at dealing with air flow, moisture, and heat and systems that capture, store, and generate energy--to make them behave--sustainably--as they should.
To build better.
Building a home better, one can argue, stands on four pillars, each of must be true. First, it must have strength, durability, the ability to weather time and the elements. Next, usefulness--it must perform well in its workings, its function as a complex of inter-operable systems aimed at comfort, safety, air quality, security, and enjoyment. Thirdly, a better home is more aesthetically pleasing, in its orientation on its land, in its elevation, and in its interior design for natural light and felicitous spatial flow, indoor and out. And last, it must feel more valuable than it costs to buy and maintain, by a long-shot.
So, if you're making homes better these days, it's hard not to make them perform better when it comes to energy. From your slab, with, say, R-10 rigid foam installed at the slab edge and interior of the stem wall, to your open-cell spray foam in your wall cavities and rigid foam on the exterior walls and roof deck, you create both a continuous thermal blanket and a moisture and air barrier, with a drainage plane behind the cladding. For the roof, it's similar, a comprehensive moisture and air barrier, with thought around ventilation, drainage, and the elimination of any penetrations possible. Unvented attics get sealed and semi-conditioned, and windows are double-pane, low-emissivity coated and argon-filled for higher performance on U-factor and solar heat gain coefficients. Sealing thoroughly, for water and air, especially at penetrations, sill plates, and windows, is better building, and it's going to save energy and money.
If your envelope measures up--with air leakage well below 3.0 air changes per hour at 50 Pascals of pressure--you can focus on your air and heat flow systems for energy management, with, say, an energy recovery ventilator to exhaust "used air" and bring in fresh, and highly-rated furnace for annual fuel utilization efficiency, air conditioner, and water heater, as well as smart tech-controlled LED and CFL lighting and Energy Star appliances.
Up to now, you've built better for how the home deals with air, moisture, and heat over an enduring period of time and use. You've also, no doubt, solved for water conservation, and indoor air quality as ways of improving the home's usefulness to its residents. This much work might get a home's performance to a Home Energy Rating System (HERS) of 50 or below, which puts it well within striking distance of Net Zero Energy once a renewable energy source--likely, photovoltaics--get added to the mix, either with a local utility or with home energy storage options.
Now, added per square foot construction costs--with PV--may model in at just under $10 per square foot, an amount that most owners would recoup in 10 years of ownership on energy savings.
For home builders, the question has moved beyond whether potential home buying customers want "green" homes or not and are willing to pay for them. The question, rather for builders, is can you risk not building homes better, and selling customers profitably on the sustaining value to them your homes offer.
The "road to zero," for most builders, is a road to building better, more valuably, and, one would hope, for net gains.