Wide Angle: How to 
Cool a City

Hot climate in the city with strong sunlight in flat design.

This year is likely to be the hottest since global records began in 1880, according to scientists at NASA, and projections from the National Oceanic and Atmospheric Administration suggest that the Northeast U.S. could see temperatures rise 4.5 to 10 degrees by 2080.

In an urban environment such as Beacon, is there anything that can be done to counteract this heat? Is it possible to cool a city?

One major factor is tree cover. The more trees, the more shade, which in turn stops light from hitting buildings, streets, parking lots and open ground. We should dramatically increase the number of trees being planted for that reason alone, aside from appreciating their aesthetic and ecological benefits.

The heat absorbed by parking lots can be significant. Paved areas can be 15 to 20 degrees warmer than tree-lined streets. These warm during the day and then release heat in the evening, driving up demand for air conditioning. Adding trees to their margins can be helpful, but an alternative is covering parking lots with solar canopies, which provide shade and solar power. 

Solar panels on buildings have a similar effect, but alternatives for cooling buildings are in wide use. Large, flat-roofed buildings can be painted white, with or without solar or other canopies. More architects are designing green buildings with gardens on their roofs (such as the Chapel Restoration in Cold Spring), decreasing heat. Existing and new buildings can block sunlight hitting windows and exterior walls with structures designed to block direct sunlight while still admitting indirect light.

Homes share the same issues as larger buildings. Solar panels can block sunlight and create electricity. Studies have shown that painting dark asphalt shingles a light color is ineffective, and costly. However, light-colored, lightweight metal roofs reflect sunlight and cool down more quickly than asphalt. At the very least, homeowners should consider light-colored shingles when reroofing.

There has been a recent breakthrough in what is the whitest of paints. A team at Purdue University has devised a paint that reflects 98 percent of sunlight. This paint can reduce surface temperatures by 8 degrees at midday and 19 degrees at night, which decreases air conditioning use by 40 percent. It can be painted on everything, not just roofs: walls, cars, trucks, streets, parking lots. It could be available commercially within a year.

Many groups are looking to reengineer air conditioners to decrease their power demands. Once they’re on the market, government regulation and consumer incentives could lead to widespread acceptance, as with the movement to ban gas stoves and water heaters and to promote heat pumps.

Beacon has no canopies, solar or otherwise, for its many municipal parking lots. The only metal roofs I have seen appear to have dark colors. In discussion with the climate coordinators of Beacon and Cold Spring, I learned that zero projects of these sorts are happening locally. 

Perhaps we’ve been lulled into complacency since we have so far been spared the devastating heat waves that have gripped other parts of the country. But our turn will come, and we’ll wish (or our children will wish) we had acted earlier when the mercury passes 100 degrees for a few weeks — or months — in a row.

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