18 October 2012 – From Atlantic Cities: Within the borders of Cambridge, Massachusetts, are 17,000 rooftops, or 17,000 individual surfaces on which it might make sense one day to install photovoltaic cells. Of course, these roofs are not all equally fit for solar power.
Some of them have weird chimneys or sloping architecture or tree shade. Some buildings are oriented in the wrong direction (for the sun’s purposes, at least), or they’re boxed in by even taller structures that block out natural daylight.
From the sun’s point of view, all of this means that Cambridge looks about like the aerial image above. The gold dots are the solar sweet spots, the brown ones are more or less untouchable. The image comes from a new mapping tool built by MIT’s Sustainable Design Lab and the Boston design firm Modern Development Studio. They’ve mashed together some pretty remarkable datasets about Cambridge to model the solar potential of just about every square metre of rooftop space in the city (literally, each of those dots represents one square metre). And the model they’ve developed could potentially give us the same information about every surface on the planet.
Notes and Dispatches from the Urban Future See full coverage
“When an owner uses the map, they get a very good evaluation of how good the solar potential of their roof is,” says Christoph Reinhart, an MIT associate professor working on the project. Modern Development Studio’s web platform can even translate that solar potential into a financial cost, a payback period, a carbon emissions reduction and equivalent calculations for how many trees you’d have to plant or fewer miles you’d have to drive to achieve the same effect. “But we’d like to now say, what does it mean for the city?” Reinhart asks. “Where should we support putting photovoltaics on roofs?”
This project assumes that we will one day be making decisions about where to put this stuff at the community level rather than the household one. “Right now it’s a bit about me, me, me,” Reinhart says, light-heartedly. “How do I get the most money?”
This map illustrates that just because you want to be that guy on the block with solar panels doesn’t mean your house is the best place to put them.