Mission: Impossible - Photovoltaic Edition
The city of Mountain View has a solar requirement that is impossible to implement, effectively outlawing medium-density housing.
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| "Honey, why won't the lights turn on???" // photo by Alex Bierwagen |
I like solar panels. I have ever since I was a child and received my first solar-powered calculator. This little strip can power this computer just from the light emitted by these fluorescent tubes in the classroom? What kind of voodoo magic is this?
I liked solar panels when I was in college, learning about sustainable design and how solar panels are a major piece of the puzzle in attaining net-zero housing. I liked solar panels when I first started working in the field, advocating their use, even before it was beneficial from a cost-benefit ratio. I like solar panels now. The only reason they're not on my house now is that we are planning to either move or add a second floor to the house in the not-too-distant future. If the latter happens, my design as it stands now would have a large piece of roof pointed toward the south, ready to receive a large array of panels, with a battery pack to store power for the night.
What I don't like is the forced addition of solar panels. I first realized this a few years into the profession, when California offered massive subsidies for solar panels well before they were cost-effective. While I encouraged people to add solar, I would never dream of forcing them to do so, or as subsidies go, force poor taxpayers to pay for solar on rich people's houses. Even strategically I don't know that it makes a whole lot of sense. Someone had to be really into sustainability for it to really work. How many of those old, less efficient solar panels that people were forced to pay for are still on those houses today? Probably a lot. How many of those people would have installed much more efficient panels as solar panel technology rapidly expanded in the past few years, yielding much higher rates of energy production? Probably at least some.
In Mountain View, an ordinance was introduced in the past few years to expand solar panel requirements, in quite literally, the most stupid application I have seen.
Excepting single-family housing, Mountain View now requires 50% of the roof to be covered in photovoltaics. That's right. Fifty. Fifty percent. Half.
This wouldn't be quite so bad if we were doing modern style townhomes with flat roofs, but in the insane city of Mountain View, this was effectively prohibited to us since the chair of the Design Review Committee has some kind of fatal allergy to modern design for housing in any density lower than mid-rises. Not only this, but she seemed to think that the more a wall undulates, the better design a building is, as if architecture has not advanced beyond the Baroque period of the Roman Renaissance.
Solar panels mounted to sloped roofs, which traditionally styled houses will have, of course, are dependent on orientation. If a solar panel on a 4:12 roof slope is pointed to the north, you're not going to be getting a whole lot of electricity out of it. You can maybe hook up a cheap Staples brand calculator to it as long as you don't have it calculate anything over five digits. On a south-facing roof, those photovoltaics would be very happy indeed. The California Building Code issues a guideline stating that roof planes which can have solar that counts toward its required solar coverage are those facing 90 degrees from true north (east) to 300 degrees from true north (west-northwest). This was actually expanded from the 2016 version of the code. Also, the code requires 15% of roofs to be able to be covered in photovoltaics. Mountain View amends this to 50% actual coverage, inside their city limits.
That's not all. The California Fire Code also details where on a roof solar panels may go. It requires a three-foot wide walking path along the ridges of roofs as well as a combined three-foot wide walking path along adjoining roof planes on at least one side of the roof plane. So, if you have a 20-foot by 10-foot roof plane, you can generally have about 17 feet by 7 feet of it covered by panels. On top of this, most solar panels are fairly large. If you have eight feet of usable area and your panels are three feet wide by five feet long, you're going to leave several feet of usable area on the table, unused, unless you go with high-priced tiled panels that are much more granular.
So now, thinking about solar panels on these sloped roofs which we were forced to do, how many traditionally sloped roofs would be able to achieve 50%?
Almost none!
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| Full range of rotation for 50% coverage, for the simplest roof possible. // sketch my own |
Then, as we were forced to complicate the roofs more and more with smaller roof planes like hips, then with many jogs in the wall plane, then with raised tower elements, then being forced to put condensers onto a partially flat roof in the center, causing much of the roof to get cut off, a solar consultant was only able to get about 10% average actual photovoltaic coverage on the roofs. That is what happens with a city official dictates design to the architect. The Design Review Committee basically forced us to crumple up our roof planes like crumpling a piece of paper.
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| Simplest roof possible which still results in <50% coverage unless within the orientation illustrated above (left), changing to a hipped roof resulting in less coverage possible (middle), adding various wings to the building resulting in sparse coverage (right). What we had to do was way more complicated than the roof on the right, though the scale of our building was larger. // sketch my own |
On the other hand, the ordinance never said the panels had to be efficacious, so it would be possible to just cover all the roofs with useless panels that would be in the shade or facing the wrong direction, a colossal waste of money and rare earth materials but would follow the letter of the law. The only other option we could think of was to reclassify the occupancy from R-2 (multi-family) to attached R-3 (single-family) utilizing some codebook tricks, but would complicate things in other aspects.
We asked the city staff and design review chair if they have ever seen a townhome project approved with 50% coverage, with the traditional styling, and we were met with blank stares. We knew the answer was no because we knew it was impossible to achieve. After a bit of uncomfortable silence, they told us to contact the building department for an answer. We did. And could not get a return email or call out of them. It wasn't until months later, our client sold the project to a builder, pursuing a building permit, that we were told the city council recognizes the defect in the code and is working to amend it. We're not holding our breath that it will actually happen with any kind of urgency though the building department did finally say they would try to work with us on it. And that's where we're at now. A promise that I wouldn't bet a penny on being fulfilled in the near future.
This ridiculous law was likely written with Costcos and Walmarts in mind, which would be easy to achieve 50%, not Spanish-style townhomes under the iron thumb of the insane DRC chair. But since nobody has done projects like these under this code, we are stalled because politicians didn't know what they were doing when they passed the law and the city staff doesn't know how to respond to idiotic laws clashing with idiot design review chairs that effectively ban medium-density housing. The only saving grace that this law isn't affecting more housing developments is that the City of Mountain View has such ridiculously restrictive ordinances aside from their solar requirement that not a whole lot of people are pursuing this type of housing in that city anyway.
