You can’t tell from the street, but there’s an extra finishing touch crowning 399 Fremont Street, the fancy Rincon Hill apartment high rise completed last month after an exhaustive development that began all the way back in 2006. (Does anyone even remember 2006 anymore? Did dinosaurs still roam the earth?)
In a bid for those ever-important LEED ratings, the SCB-designed building sprang for a gigantic solar water heater on the roof. Basically, it's an apparatus that heats water through solar power — a gigantic, 5,000 gallon water heater running off the sun.
It might sound pedestrian, but this is actually a clever bit of design ingenuity, tailored to San Francisco's particularly unwieldy climate. We can break it down by the numbers:
5,000: The number of gallons this thing can handle. The enormous, expoxy-lined vertical reservoir is attached to the building core, and had to be specially fixed for seismic safety. (The last thing you need in an earthquake is 41,000 pounds of water falling from 42 stories onto you. Cal Solar Inc says this is the tallest such system in the world.)
1.2 million: The number of cubic feet of natural gas that will be saved if the rig operates at the estimated 12,000 therms per year it’s supposed to. A therm is equal to the amount of energy you get out of about 100 cubic feet of natural gas. Each therm costs about $1.50 a pop in California, by today’s prices.
2,500: The number of Varisol tubes covering the rooftop. Rather than flat panels, 399 Fremont uses glass vacuum tubes that absorb solar heat. Manufacturers say this sort of system is ideal for cool days and foggy climates so that your solar system doesn’t have to be constantly baking in the sun to generate.
20: The number of degrees all 2,500 of those tubes are angled at. To catch the maximum amount of sun, a solar collector should be placed at an angle roughly equivalent to the latitude of your building. In the case of the Rincon Hill tower, that’s 37, but the angle of the roof must be accounted for too.
399 Fremont is Back [Curbed SF]