Earlier this year, Altostratus and CalEPA rolled out a UHI Index that quantifies the intensity of urban heat. For the first time, we can now measure and visualize the severity of the heat challenges facing cities. You can check out the details from CalEPA here. This really is a great new tool that we’d like to see spread across the country and beyond.
As you’d expect, most of the media coverage of the UHI Index has been positive. Several articles noted that the Index highlights the challenge of addressing UHI at a local level because heat transfers from one part of the city to areas downwind. This finding highlights the importance of a regional approach to urban heat.
A few articles (like this one) note that increasing reflectivity above some threshold can be bad for cities. This is a misreading of the Altostratus analysis. Rather than a threshold between good and bad, the analysis identifies that there are optimum amounts of reflectivity. Cities exceeding that optimum level will see diminishing, but still positive, returns.