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A comparative analysis is made of the thermal performance of a small office building using various HVAC systems and commonly emDloyed strategies. The comparisons are made for seven geographical locations representing xyide climatic variations within the continental United States.Results were obtained for fan, space heating hot water, and chilled water energv consumption through hour-by-hour simulations using the BT.AST computer program. A small office building model was used in the simulations along with several HVAC systems; a constant volume reheat unit (serving the entire building), dual constant volume reheat units (serving separate zones of the building), and a variable air volume reheat unit. The strategies investigated included simply air temperature reset (constant, zone-controlled, and outdoor air-controlled), economy cycles (temperature and enthalpy), continuous conditioning versus conditioning only during occupied hours, changes in reheat set point temperature, and changes in minimum variable air volume ratio.For comparable control strategies, the variable-air volume terminal reheat system exhibited the least energy consumption for chilled water, hot water and circulating fan. The system incorporating two independently-operating constant volume terminal reheat units ranked second in energy consumption while the single constant volume terminal reheat unit ranked last.Changes in thermal performance resulting from implementing one strategy in place of or in combination with another were found to vary significantly by climate and the type of HVAC system employed.

This report is one of a series documenting NBS research and analysis efforts in developing energy and cost data to support the Department of Energy/National Bureau of Standards Building Energy Conservation Criteria Program. The work reported in this document was performed under the Energy Analysis of Control Strategies project, a part of the controls program element managed by Building Systems Division, Office of Building Energy Research and Development, U.S. Department of Energy. The NBS effort was supported by DoE/NBS Task Order A008-BCS under Interagency Agreement No. EA77A 01-6010.