This weekend 177 new trees will be planted in Portland. Why is that a big deal? In the summer the streets serve as a heat sink. Asphalt is black not white like my porch. There is in architecture a design concept called passive solar design. It was the rage in the 70's. It is a very old concept though. Thermal massing is used to capture heat during the day and to let off during the cooler times; night.
Streets have a thermal storage capacity that often goes unrecognised. It is the same concept that is used for passive solar. There is a mass that takes the heat in when the sun is on it. It is released at night. Black attracts the most heat, white attracts the least. Our city streets are black and there is often no mitigating factor like trees. They prevent the heat absorption.
Now to my porch experience. I have a big concrete porch that faces west and has southern exposure. Last summer when it was really hot I put curtains out to shade my porch. It cooled my house! There was not a huge heat sink emitting heat. This is very basic. And I think we have lost sight of how important shade is.
