Ochogon: A Sustainability Story (Part II)
Part II — Ochogon and Meaningful Energy Conservation
Click here to return to Part I: The Scale of Sustainable
“Ooh, there’s that new megamall they’re building. They say the air conditioner will be more powerful than a million hydrogen bombs.” — Marge Simpson
Since air conditioning became cheap in the middle of the last century, Tucson, Arizona has been one of the fastest growing places in the country. My sister Kristen and her then husband Doug moved out there in 1994. Among their many adventures was the construction of Desert Home, a 1,500 square foot, two bedroom, one bath, off the grid, solar powered, rain water fed, piece of certified genius way out in the desert southwest of town.
Desert Home is pretty much impossible to really “get” without going there and spending a few days experiencing what truly sustainable living is like. Short of doing that, this video, produced and narrated by the home’s creator, my now ex-brother-in-law Doug, is a good place to start. The whole thing is a little less than half an hour and demonstrates just why Desert Home is both an excellent place and truly sustainable.
The one drawback to Desert Home is that it is unique. It’s the best possible home that could ever be constructed in that location, but while it demonstrates a lot of lessons about sustainable living, it cannot simply be replicated in other places. Enter the Ochogon.
In 2001, Doug and my sister moved away from Arizona and weren’t sure when they’d be back. Before they left, I helped Doug put up the frame of Desert Home’s successor: Ochogon. Like Desert Home, Ochogon’s walls are made from rastra block, which is mostly recycled styrofoam mixed with a little concrete. As a building material, it’s got a lot of advantages. It’s tough. It’s highly insulating. It’s easy to work with. And it comes in ten foot lego-style blocks that you can cut into any shape and configuration you like. Filled with rebar and concrete, those walls could theoretically last longer than the Pyramids, so Doug had no worries about abandoning it to the desert for a decade and a half.
Earlier this year, a number of pieces clicked into place and Doug and I got the opportunity to go back to Arizona and put a roof on Ochogon. We were out there for four weeks and managed not only to get the roof up, but also add a porch from our left over roofing materials.
We’re planning to return in the fall and do the interior. But even in its present skeletal state, Ochogon is already a far more sustainable building than many of the other houses that have been thoughtlessly plopped down in fast growing Tucson since 2001. Consider, for example, “Sonoran Ranch”, which we drove by many times on our way to Lowe’s and Home Depot. Here it is on Google Maps:
In one — and only one — respect, this is smart development: it’s dense. In every other way this is a sustainability nightmare, and even the density is wasted because it’s miles from anything except other residential developments:
The only thing that’s walkable from these homes is other homes, and there isn’t a mass transit option in sight. Driving — lots of it — is the only way to get there and back. Worse, these houses are mostly big, and many of them are two stories. In cities, where land is scarce, multi story development makes sense. Way outside of Tucson in the desert, where land is plentiful and heat rises with a purpose, a second story is basically a giant energy suck, one that’s going to need to be air conditioned all night long for months on end.
This is construction with no regard whatsoever to local conditions, and the result is dwellings that barf carbon into the air far worse than even the heaviest Hummer or stupidest muscle car. So why are we building places like this? Because they come with low sticker prices and easy to slice 30-year mortgages that bank algorithms can write in their sleep.
In the long run, that’s Mad Max level bad, but here’s the really funny part. On the LGI Homes website for Sonoran Ranch, there’s a big box lauding “ENERGY EFFICIENCY”. (It’s even got a stock photo of a leaf with water droplets on it, so you know it’s green as fuck.) Here’s what it says:
Affordability and Sustainability
Since our inception, we’ve made a commitment to offer our customers the most affordable homes around, but we don’t think affordability should be limited to the price you pay for your home at closing. We believe affordability should extend throughout the years that you call your house “home,” and strive to offer energy-efficient homes that will lower your bills for years to come. It’s estimated that 20–30% of your energy bill can be attributed to your appliances, and the appliances we install use roughly 30% less energy than standard appliances. This could save you money each month on your energy bills which stacks up to major money in your wallet over time. Additionally, our energy efficiency standards don’t just help you save money — they help save the environment. Our homes help limit the amount of resources needed to heat, cool, and power your home, which translates to less stress on the Earth. Truly, we’re a leader not only in affordability; but also in sustainability.
What scale of bullshit is this? Let’s do the math. If 30% of your energy bill is appliances, and they install appliances that use 30% less energy, that’s 0.3 x 0.3, or 0.09 of the energy usage of these houses. Now, 9% is nothing to sneeze at, but it’s about as adequate to “save the environment” as a roll of gauze is to save a multiple gunshot victim. For bonus fun, the paragraph before the above touts the “insulation, heating and cooling systems”, but doesn’t mention any numbers. And nevermind that all that these houses are far away from everything and many of them are two stories high in the middle of the desert. Here’s what it looks like from the street:
The LGI website lists two types of two story houses at Sonoran Ranch, the “Cimarron” (at 2,500 sq ft) and the wonderfully ironic “Snowflake” (2,000 sq ft). These are houses that would’ve been considered large to huge as recently as the 1980s. Today they’re not even average, and each one is going to spend the life of its mortgage (and then some) eating energy. In the summer, when that 5,000Whr air conditioner will be running 24/7, cooling just one of those houses will use the same amount of electricity as driving a Chevy Bolt the 400 miles from Tucson to San Diego . . . every day. A 9% savings from efficient appliances (itself a generous estimate) is a bad joke next to that.
Ah, but what about those solar panels? We’ll get to them in a second. First, let’s return to Ochogon, which solves the “how do you power the AC?” question with the simple and elegant solution of not having one. Here is the interior of Ochogon’s roof, about a third of the way through construction:
As any six-year-old who enjoys balloons can tell you, warm air rises. Air conditioning a second story in the desert fights that natural tendency by sealing the house as tightly as possible and attempting to keep an even temperature through massive application of energy. Ochogon uses that basic natural principle to draw heat away from the living area, up to the ceiling, and then out the roof. No energy usage required.
The Ochogon roof is basically four layers: rafters, covered by plywood, covered by a thin sheet of underlayment (for thermal and moisture insulation), covered by metal sheets. The metal (steel with a copper colored paint job) reflects most of the Sun’s energy, the unerlayment insulates the plywood, and the warm air inside the house rises through the rafters and out the roof and top windows. One of the most remarkable things during construction was how quickly this effect took hold.
Even with the top cap sealed by plywood (where there will eventually be windows), the interior was consistently 10F-15F degrees cooler than the outside. And if you got a bit of a breeze through the windows, it was even better. This is passive cooling, something that people living in warm environments used successfully for millennia before the advent of freon and compressors.
Ochogon may eventually get a ceiling fan to help with circulation, but that uses a mere 75W, compared to 3,000–5,000W for a stand alone air conditioner. That huge discrepancy brings us back to solar panels. This is the satellite view of those same Sonoran Ranch houses from above:
To minimize shadows and give the best top down image, Google Maps uses satellite photos taken at noon. The house with the solar panels on the south facing roof appears as a blue-white blur because the panels are angled so that the noon sun is hitting them directly, hence the glare bouncing back up into space. The house further down the street has an east-west facing roof, and panels on both sides that will never get the kind of direct sunlight that maximizes solar output. I don’t know the type of panels each home is using, but sun angle has a huge effect on how much power a panel can generate. So despite the east-west house having twice as much solar square footage, it’s almost certainly generating far less power overall.
The kicker is that even the good, south facing system there is wholly inadequate to power even just the air conditioner. Tucson is a great place for solar, and on a sunny day those cells will produce quite a bit of juice. But cooling the upstairs rooms that sit below those panels probably takes all of the energy they generate in summer and then some. It’s nice that there’s solar panels, and that they’re installed well, but in that location and with that design, no amount of roof panels could get that house to energy neutral. Those panels are a fig leaf, a conscience salve, and maybe even a tax break, but they don’t make the house sustainable, no matter what LGI’s website says.
Unlike those houses, Ochogon is built to work with its surrounding environment. The south and southwest walls (which get the most sunlight) have no windows. The porch roof will block sunlight from hitting the doors, especially in summer when the sun is most intense. Windows opposite one another allow for maximum airflow. And those thick, rastra block walls act as thermal regulators, slowly absorbing heat during the day and then radiating it at night, helping to keep the interior at a relatively constant temperature even as the outside environment swings forty degrees or more.
If we’re going to have any chance of cutting energy usage 50%-80%, we need a lot more Ochogons and a lot less Snowflakes and Cimmarons. More importantly, we need to work the ideas behind Ochogon (and Desert Home) into standard building practices.
