Modeling the Effects of Street Trees on the Performance of Solar and Conventional Houses in Sacramento, California

Abstract

Street trees have potential for both the beneficial shading of houses during the hot season and the detrimental blocking of incident radiation to solar collectors. Although some states and many local governments have passed regulations to protect solar access from obstruction by vegetation, street tree planners have inadequate data upon which to plan for the necessary trade-offs between providing shade and solar access in much of the temperate United States.

This study describes the computer modeling of the thermal/energy responses of three test houses (solar, conventional, and solar retrofitted) having a continuous row of street trees to the south of the dwelling. Four trees—three deciduous and one evergreen—were tested; each tree was considered at three different setback distances from the south wall of the house. A “no tree” condition was also tested for each house. Predictions were made for annual energy costs for each test house under each tree and setback condition; these results indicated a significant net increase in annual energy costs when street trees were placed in the zone directly south of a solar house.