“A House That Is as Green as It Gets”
That was the title of an article in the NY Times last week (https://www.nytimes.com/2023/05/04/realestate/net-zero-house-california.html )
I realize the article is paywalled, but see if you can get past the paywall. The writer makes a big deal of the house being net-zero. But it’s in San Mateo, CA. I looked up the weather stats (https://weatherspark.com/y/560/Average-Weather-in-San-Mateo-California-United-States-Year-Round ) and this is a place where the day with the hottest average temperature is September 11, when the average high is 74F, and the coldest day is December 31, when the average high is 56F. From May to November highs are in the 70’s. The 99th percentile heating temperature is 31F. So basically, you don’t really need heating or cooling.
Let’s just say the house looks nothing like a PGH!
Then there’s this bit:
“Those beautifully striated 18-inch-thick walls, made of compacted soil gathered from the site, were engineered by David Easton, an inventor in Napa, Calif., who concocted the blend of sand, earth and Portland cement. They are low-maintenance and rot-resistant, and their thermal mass shields the interiors from outdoor temperature fluctuations. This feature minimizes the use of hydronic heating and cooling systems embedded in the wood-covered concrete floors inside.” OK…
The house is 7,477 square feet. And has a pool. But it’s “green as it gets.”
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Rich folks sure like to congratulate themselves.
A house that needs almost no heating or cooling, yet it has two mechanical systems. Honestly sounds like the house is as wasteful as it gets. But hey, they used as many exotic "green" materials as they could get their hands on.
It's nice to see articles about houses that are smaller than average, or that show building an efficient home doesn't have to be double the cost, or exotic for that matter. Unfortunately, these don't catch the eye of the public very well.
I saw the article, was no comment section available unfortunately.
They paid $2.675 million for the less than one acre lot. House probably cost $5-10 million. That's the only kind of green one can associate with the place.
When I get rich, I'll have a 200 foot boat, a sailboat, so I don't use any fossil fuel, except for the helicopter.
There is a fine line between a project like this, which appears to be blatant greenwashing, and "leadership projects" that may be beyond the budget of most people or not green in every way but that serve as test cases for sustainable features. I'm not sure where that line is or how much value "leadership projects" really have, but I think their impact is probably substantial, and proportional to how well they are publicized.
Michael: We read about a lot of commercial and institutional projects that push the envelope as test cases. Colleges, municipal buildings and the like are perhaps better placed to invest in sustainable features not yet seen in homes. The house described above sure looks like greenwashing, rather than someone trying to see if an emerging technology really is effective.
The title is definitely greenwashing. But I've had a couple of projects lately that might fit into the same category as the one described, so I've been thinking about it a lot.
As large as 7500 sf is, what if without being "greenified" it would have been 10,000 sf or more? The walls are thick and no doubt expensive, but I'm sure they're beautiful and likely low-carbon, wildfire-resistant and otherwise durable for the local conditions. Would a larger house with code-minimum walls be greener? A pool is a luxury, but in hot climates they have some practical benefits, and maybe the pool is smaller than it could have been, or maybe it's a natural pool that uses plants for filtration rather than chlorine or bromine. How does a small pool that doesn't need to be heated compare to having a hot tub in a cold climate? If that is their only home, how does it compare to someone with multiple homes? It's net zero, and near city services--depending on how they get around, how does that compare to someone who lives in the woods and needs to drive to get anywhere, or to someone who does not have PV panels?
I'm not saying everyone should build 7500 new homes, and I'm definitely not saying it's the greenest house, but if it's better than it could have been, that's a central tenet of Pretty Good House, and of the Not So Big House approach. We talk a lot on GBA about how to make houses slightly better than code minimum, but they are usually larger than "necessary," often located in not-very-green locations, and virtually always include a lot of materials and equipment with high levels of embodied carbon. We can get smug that our particular preferences are superior, but as Martin has written before, if we're not basically living in huts, we're not being as green as we could be.
The walls are a "blend of sand, earth and Portland cement." And 18 inches thick. That doesn't sound low-embedded-carbon at all to me, cement is atrocious.
But I agree with your larger point, which is that we've been conditioned to think about environmental issues as matters of personal choice -- and personal virtue. The reality is that these issues are systemic and are best dealt with in that way. For example, the greenest thing that you as an individual can probably do is sit down and write a thoughtful and well-reasoned letter to your state representative, urging that your state adopt the most recent energy efficiency code. Doing so would dwarf any lifestyle choice you could make in its impact.
What I found frustrating about this article was the complete lack of skepticism and broader awareness on the part of the author.
High mass walls don't reduce energy loss, either, they just act to sort of "average out" the temperature variations over time. Insulation acts to reduce energy loss. I would say that from an energy use perspective (which is what I'm usually working towards), insulation is greener than high mass walls.
I don't think the most recent energy codes are entirely "more green", either. Many of the requirements are starting to get into the diminshing returns area, which means that the money spent to meet some of those codes would be better spent elsewhere, i.e. you'd get more "bang for your buck" by spending the money for something else. I suspect that the R49 to R60 requirement for attic insulation in some climate zones is getting into this territory, although I haven't bothered to actually run any calculations.
If you spend $200 to save $50 of energy over the life of the home, then that's not a good allocation of resources, and likely means you actually used more energy to make the "energy saving" thing than you actually saved with the energy savings that "energy saving" thing provided. When you start doing that, the "green" thing is actually worse than nothing, and not at all green. I see people make these kinds of mistakes fairly often, which is why I'm always saying that it's important to consider the entire system as a whole and not be overly focused on any one part of it. The goal should always be the lowest OVERALL energy consumption. A simple example would be to build an entire home with code minimum levels of insulation, but then use the absolute most efficient possible LED light bulb in your porch light. Sure, that suped duper LED bulb is saving energy, but it's nothing compared to the energy losses through the walls and other areas of your code-minimum home.
David Easton is a real artist and his designs are breathtaking. But I believe the environmental impact of the cement in his walls is selectively ignored when people want to tout the "green" aspect of his work.
I believe his mix includes 7-10% cement by weight. Given the amount of mass in one of his houses and the fact that no cement is required in a wood framed wall, I think the cement contribution is not negligible.
There are people, including Easton, working on the issue of how to reduce the cement content though. My favorite group at the moment is joint French-UK research group called the CobBauge Project, operating out of Plymouth University.
They've developed a very interesting system using straw and clay. They have a denser mix that is structural and which gets tamped into a form, half-filling it. Then a lighter mix fills the remainder of the formwork to provide insulation. The whole gets a coating of clay or lime based plaster as a finish.
I know I'm well-known here as a skeptic of the powers of "thermal mass," but a house like this is Exhibit A as to why we should be skeptical. Eighteen inch thick concrete walls, floor to ceiling glass elsewhere, it doesn't look like there's a lick of insulation in the whole thing.
And when they say the walls were "engineered by David Easton," I'm willing to bet that the extent of the engineering was to insure they could hold the weight of the building -- that no energy modeling was done.