Center for the Built Environment

A naturally ventilated office building in Alameda, CA with operable windows and ceiling fans was monitored from Oct 2011 to Oct 2012. Physical environmental parameters such as dry-bulb air temperature, humidity, CO₂ levels, outdoor wind speed, hourly window positions, heater settings and fan settings were recorded. Occupants were surveyed regularly over a period of one year about their current thermal comfort, thermal acceptability, air movement satisfaction, clothing and noise satisfaction. Occupants wore clothing with a clo value of between 0.5 – 0.6 during summer, and 0.7 – 0.8 during winter. The clo value of the occupants clothing was most closely correlated with the outdoor running mean temperature. Occupants start opening windows when the outdoor is at 16 °C. Window opening was strongly related with occupant’s arrival and outdoor temperature. Fans use was best explained by indoor temperature. Fans were typically turned on during the summer at indoor temperatures above 26 °C. Occupants voted that the thermal environments in the building were acceptable 98% of the time during the year-long survey period.