The “Green” House Effect

The NYTimes carried a story on March 10 about a controversy over plans to build a very large home in Berkeley, CA. The plans which have been approved show a total area of about 10,000 square feet, of which 3,500 are for a garage. The owner, Mitch Kapor, is the founder of Lotus and has used his ample wealth for many philanthropic ends including many concerned with the environment. Perhaps he lost so much of his money in the crash that he plans to operate a public parking lot.
The controversy here rose from the designation by a city board that the house qualified as being “green.” Such designation comes via an evaluation scheme that gives points to green features of a building, for example, the use of low-flow faucets and low-volatility paint. The Kapor plan received a score of 91 points, far above the minimum of 30 needed to qualify for a green designation.
The architect noted Kapor’s environmental largess but offered no details on the process. Neighbors and others are appealing the decision to approve the plans. Another architect, William Harrison who builds big houses for wealthy clients is quoted as defending the practice.
> William H. Harrison, an Atlanta architect with a stable of wealthy clients, said penalizing people for building large houses could slow the adoption of green building practices. “The people who can afford the green technologies are going to want large houses,” he said. And those innovations, he said, will trickle down to smaller houses.
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> Mr. Harrison said that one of his clients is planning to build a 25,000-square-foot house in Los Angeles. But he opted out of the LEED system, Mr. Harrison said, when he learned that it was virtually impossible to get the highest LEED rating, known as platinum.
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> “He’s a billionaire, and he drives a Prius, for God’s sake,” said Mr. Harrison of his client. “He wants to do the right thing, environmentally. And now he’s being told, ‘You’re not good enough, because your house is too big.’ ”That, Mr. Harrison said, “is about socialism, not sustainability.”
Harrison misses the point entirely. It’s not at all about goodness or intention. It is simply a matter that such large houses create enough negative impacts to overcome the benefits by implementing green features whether according to the LEED or any other scoring system such as is used in Berkeley. What this has to do with socialism is beyond me.
In a 2005 article on the environmental impact of house size in the Journal of Industrial Ecology (Disclosure: I am one of the editors of this journal), the authors, Alex Wilson and Jessica Boehland say:

As house size increases, resource use in buildings goes up, more land is occupied, increased impermeable surface results in more storm-water runoff, construction costs rise, and energy consumption increases. In new, single-family houses constructed in the United States, living area per family member has increased by a factor of 3 since the 1950s. In comparing the energy performance of compact (small) and large single-family houses, we find that a small house built to only moderate energy-performance standards uses substantially less energy for heating and cooling than a large house built to very high energy-performance standards.

The article continues with data that show that the impact of house size is not linear; the impact increases disproportionately with size. A house twice the size of the average dwelling (about 2,500 square feet) would typical have about three times the impact based on the materials used in construction. Heating and cooling energy use depend on the details of the design and cannot be compared in a general way.
There’s another very important lesson here besides the substantive issues of the actual environmental impact. Green scores simply do not tell the whole or even enough of the environmental story to be meaningful. There is always an “other things being equal,” qualifier in the background. In this case it would be another 10,000 square foot house using less effective features. The billionaire’s Prius sounds good compared to a Hummer, but can’t come close to a bicycle’s low impact. I say this not as a value judgment on the choice of a large house, hybrid vehicle, or anything for that matter, but as a criticism of the utility of scores as valid indicators of greenness. Quantity or volume almost always trumps lower scores.