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Dedicated Outdoor Air Systems (DOAS) are proven to be beneficial in many practices. However, not all DOAS configurations under different climates provide the same benefits. This study presents a simulation on evaluating various energy saving benefits of different DOAS configurations among diverse climate zones of commercial buildings in the United States.
Three DOAS configurations in a medium office building are simulated in this study: (1) fan-coil units (FCUs) as terminal units with a DOAS unit supplying conditioned outdoor air (OA) to each FCU intake; (2) FCUs with a DOAS unit supplying conditioned OA directly to each occupied space; and (3) a DOAS with active chilled beams. A baseline system consisting of a conventional Variable Air Volume (VAV) system was also simulated for comparison to the three selected DOAS configurations. All simulation inputs are recommended by Department of Energy (DOE) benchmark reference models. Validations of the baseline system and three selected DOAS configurations are based on and compared to previous studies in literature. Building energy simulation results were collected for each system listed above. Additionally, two energy comparisons were performed: each DOAS configuration was compared with the baseline system, and a comparison of each DOAS configuration to the other DOAS configurations was made. Comparison of the simulation results indicates that DOAS energy savings ranged from 7.1% to 26% between the seven simulated locations when compared to simulated baseline with some DOAS configurations performing better in particular climate. The major energy savings are accomplished due to DOAS requiring the exact amount of ventilation for each space and employing high efficiency local Heating, Ventilation, and Air Conditioning (HVAC) units. Suggestions given as a result of this study include: (1) consider supplying the conditioned OA directly to each occupied space with a DOAS in all simulated locations, and (2) consider employing active chilled beams as the local terminal HVAC units in locations which experience extreme hot summers, such as Miami and Phoenix.
Advisor: Josephine Lau
Copyright 2014, Shihan Deng