When thinking about places where summer heat is the worst, Massachusetts is not typically high on that list. But, in urban areas around Boston, the amount of pavement and the heat island effect can increase local temperatures 10°F above that of the suburban areas. These higher temperatures are particularly noticeable at night, as the asphalt holds onto the heat radiating it into the air well after sunset. Higher nighttime temperatures are believed to produce health effects from lack of sleep – especially for those without air conditioning.
So, leaders in Chelsea and Cambridge are using a new mix of asphalt that has lighter colored aggregate and then bead blasting new pavement to dull the color from a dark black to gray. The gray pavement can reduce surface temperatures by over 20 degrees and reflect far more sunlight back to space during the day.
City officials also experimented with painting pavement to reflect more sunlight. This is feasible in parking lots, but impractical on roads because the high reflectivity impairs drivers. An MIT study suggests high reflective pavements can reduce average summer temperatures by 2.5 degrees and the number of summer days above 105 degrees by 41%. So, the next time you see gray pavement, know that you are driving on a surface that helps keep the community a little cooler. – Steve Terry, DTC HVAC & Refrigeration Instructor
