Rick Reynolds of Bensonwood takes a stab at the question.
We have tried to answer this question so many times on TreeHugger. We have read Lance Hosey's book on the subject, The Shape of Green. We have studied Steve Mouzon's Original Green but still never have come up with a great definition. Now Rick Reynolds of Bensonwood, the big timber frame company, has a shot at it.
He illustrates his post with some of his monster second homes in the countryside, so this is, to some degree, a "do as I say, not as I do" list; but the company is also responsible for the Unity Homes prefabs that we love, so he gets a pass on that. And he starts off so well:
Some have said that the “greenest house is the one that is already built.” While in many cases this may be true, one could make a compelling argument that the “greenest house” is actually the one that is least likely to be torn down.
He then starts with his main points, which are very similar to Steve Mouzon's principles from the Original Green, but in many ways go further. Some of his points:
Beauty is vitally important to sustainability. First and foremost, for a house to be saved over generations, it must be loved over generations.
In Original Green, this was called lovability, because it is so hard to define beauty, but whether one loves something is a more straightforward emotional reaction.
Durability is an essential component of sustainability. Houses should not be considered disposable. The energy and material that goes into building a house comes at a serious cost to our bank accounts and to our environment. Houses, therefore, should be built to last for centuries.
So much of what we build is cheap and disposable, sticks, styrofoam, and stucco.
Functional Adaptability allows homes to adapt to our changing needs over time. No one can predict what those future needs will be, but Open Building protocols permit simple changes to a home’s functionality, without the necessity for demolition and reconstruction involving multiple trades and overburdened landfills.
This is Mouzon's Flexible, but Bensonwood has taken it so much further with their adoption of Open Building, which recognizes that different systems have different life spans and a house should be designed to adapt. I had to rip my house apart to get rid of knob and tube wiring; I might have to rip it apart again to go DC some day. In open building, all those wires are accessible. Almost nobody does this and everybody should.
Healthy, quiet, light-filled, interiors: The Next Big Thing is the healthy home (we have been running a series on it) and studies have shown how bad noise actually is for our health.
Draft-free thermal comfort is another item that people are just beginning to understand -- how being comfortable is far more than just adjusting a thermostat. See why we should be talking about comfort, not energy efficiency.
Low Load Thermal Performance and Low Operational Costs are related.
Poorly insulated, drafty houses, requiring massive amounts of fuel to heat and cool, cannot survive long in a world of limited resources and carbon-based, atmospheric pollution. Conversely, highly-insulated, tightly-sealed houses with small, sophisticated HVAC systems can sip rather than gulp fuel, to the point where inexpensive, clean energy generated from the sun or the wind is sufficient for thermal comfort.
Rick goes on to discuss "cultural sustainability": "If a house is historically significant, its cultural importance may trump its sustainability." This is crazy talk for a builder, words that even historic preservationists like me have trouble convincing people of. He concludes:
Ultimately, taking the long view is what true sustainability is all about. Crafting new homes that are worth saving is key. To that end, we can build our way to a “greener” future.
This is a sophisticated look at a complex subject. One might add a few more points about location and density, but it is a great place to start in any discussion of building the greenest home. Read the whole thing at Bensonwood.