Effect of Daylighting on Energy Consumption and Daylight Quality in an Existing Elementary School
Atre, Umesh Vinayak
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This research investigates the effects of daylighting in an existing elementary school in College Station, Texas. The conclusions are generalizable to similar school designs in hot and humid climates. This study focuses on the trends observed in the building??s heating, cooling, and lighting energy consumption due to daylighting, and the overall effect on total energy consumption. Skylights with 1% to 10% glazing surface to floor area and clerestories from 2 ft to 8 ft glazing height were analyzed to formulate balanced daylighting designs that could provide for decreased electricity and gas energy consumption and increased daylight illuminance levels and energy cost savings. Classroom and Library areas inside the case study school building were analyzed using walk-throughs and daylight factor measurements to understand existing lighting conditions and the potential for daylighting. Physical scale models of the study spaces with and without daylighting alternatives were built for daylight factor and daylight penetration analysis. Computer simulation models were created for the base case and all proposed daylighting designs for building energy performance evaluation using the DOE-2 building energy simulation program. Daylight factors from the actual spaces, physical model measurements, and computer simulation outputs were studied for trendsin interior daylight illuminance levels. Annual energy consumption analyses were performed using DOE-2 and involved heating, cooling, and electrical energy use comparisons of all proposed designs with the base case. One design each from the skylight and clerestory cases, and an overall design based upon the performance criteria are proposed for the existing school building. The building energy analyses suggested that a considerable reduction in artificial lighting and total electricity use could be achieved through proper sizing of skylights and clerestories. Heating energy use stayed almost constant in all cases. Considering all different trends in energy use, all the proposed cases perform better than the base case in terms of total energy savings. The spaces analyzed constituted 15% of total school area, and projected savings would be much higher if daylighting could be applied to the entire school building.