Center for the Built Environment

This project was a simulation study of the energy performance of a prototype three-story office building configured for both conventional overhead (OH) air conditioning and underfloor air distribution (UFAD). Both the annual energy consumption and the peak demand were calculated using EnergyPlus v3.0 for the building in three California climate zones, Los Angeles, Sacramento and San Francisco. The sensitivity of the energy performance to the building configuration (e.g., window to wall area ratio, etc.) and other features of the building was studied. The main result of the study was that UFAD provides energy savings compared to OH in all three climate zones, both in terms of annual energy consumption and also in the reduction of peak demand HVAC annual energy reductions were greater in San Francisco but only marginally better than in the warmer climate zones of Los Angeles and Sacramento. A second major outcome of this study was improvements to the UFAD implementation in the recently released EnergyPlus v3.1. These involved improvements in stratification modeling in interior zones, addition of perimeter zone stratification models, creation of a whole building template model, and user documentation to eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. facilitate use of the new capabilities. Finally, the effectiveness of various demand response actions such as raising the room setpoint temperature and reducing internal lighting and equipment loads was evaluated. Raising the setpoint temperature was found to be the most effective measure to reduce peak demand.