Peak power and cooling energy savings of shade trees

In summer of 1992, we monitored peak power and cooling energy savings from shade trees in two houses in Sacramento, CA. The collected data include air-conditioning electricity use, indoor and outdoor dry bulb temperatures and humidities, roof and ceiling surface temperatures, inside and outside wall temperatures, insolation, and wind speed and direction. Shade trees at the two monitored houses yielded seasonal cooling energy savings of 30%, corresponding to an average daily savings of 3.6 and 4.8 kWh/d. Peak demand savings for the same houses were 0.6 and 0.8 kW (about 27% savings in one house and 42% in the other). The monitored houses were modeled with the DOE-2.1E simulation program. The simulation results underestimated the cooling energy savings and peak power reductions by as much as twofold.