I get asked this question (or some variation of it) frequently (and in fact was "misrepresented" in an interview with The Wall Street Journal where they shrunk what I said to imply that the cost is outrageous!) and I find answering it quite difficult.
Here's my response to a recent query about "how much the renovations cost.":
"So…your question was how much the “renovations” cost. This is a tough question. Because the cost of our project is impacted by many factors—not all of them “green.” First of all, this is a very custom home: we’re talking things like very custom millwork and a 10K custom hand-crafted glass mosaic breakfast bar and a cupola and custom-made metal stairs. Things like that. Also, we chose very nice features—not necessarily always just the affordable option. Secondly, this was a demonstration home which meant that it had to be built on a schedule and it had to be, well, perfect. It was going to be on show. We also paid for the services of a marketing manager, a website designer, marketing materials, educational materials, etc. Those things contributed to the cost. Thirdly our building project was, well, our building project. That is to say, we had our own special set of circumstances that impacted cost: size, location and accessibility of the lot; the fact that it was custom and required an architect; the fact that based on the location and the amount of glazing we wanted—and that little thing called a cupola--required the services of an engineering firm. We also went for 5 certifications which required the services of a green construction professional whose only job was to make sure we were meeting those requirements. That cost more money. We also had help from sponsors (no, we did not get our house for free or even close!) but that often meant that we ended up spending more $$ because we went with their products instead of really shopping around. A good example is Kohler. They were kind enough to sponsor us (which means they cut us a significant break) but demanded that they be the only plumbing supplier. And Kohler is not only expensive but installation of Kohler products is more expensive.
See what I mean? So when people ask me how much more our house cost because it is green that’s not such a straightforward question. Here’s an example: our no-VOC paint by American Pride retails for $39/gallon. We could have purchased: )a Benjamin Moore that wasn’t green for about the same price; or b) we could have purchased a much cheaper non-green option at Home Depot. So against which should I make the $$ comparison? Another example: We went with all hard-surface flooring partly due to our American Lung Association Health House requirement (and because we personally think carpet is gross!). Our bamboo, and cork, and FSC teak and Marmoleum could be considered more expensive compared to inexpensive carpet and vinyl but in terms of general quality I think they compare more to a pricier carpet option. So, again, against what are we making a comparison?
Could we have built our home cheaper by not paying attention to quality or greenness? Absolutely! But we wanted to build the house we wanted, we wanted it green and we wanted it to be good quality that would last—an important component of green building.
Sorry for the diatribe—and for not really answering your question (no, I was not a politician in a former life!) But hopefully this will help you understand the difficulty in answering your seemingly innocuous question."