Energy Benefit of the Underfloor Air Distribution System for Reducing Air-Conditioning and Heating Loads in Buildings

Although there have been continuing efforts recently for low-energy buildings as parts of the low-carbon green growth movement, particular attention has been paid to architectural design, the elective control of façades, and the efficiency of Heating, Ventilation, and Air Conditioning (HVAC) mechanical systems. To maximize the gains from these efforts, it is essential to consider the energy distribution approach and its layout during the design stage of the building. To this end, air distribution principles in HVAC have grown in popularity in buildings. The method to deliver the energy is strongly associated with increasing concerns about indoor environmental quality on occupants’ well-being, as well as rising energy costs for space heating and cooling. This paper identifies types of air distribution systems for heating and cooling in buildings and addresses the potential energy benefit of an underfloor air distribution (UFAD or UAD) system over the conventional ceiling air distribution system. A series of EnergyPlus simulations shows performance differences between the two distribution systems. One result is that the potential benefits of an UFAD are clearly demonstrated for a large space with a high ceiling.