Energy and first costs analysis of displacement and mixing ventilation systems for U.S. buildings and climates

Abstract

In the past two decades, displacement ventilation has been increasingly used in Scandinavia and Western Europe to improve indoor air quality and to save energy. By using a detailed computer simulation method, this study compared the energy consumption of a displacement ventilation system with that of a mixing ventilation system for three types of U.S. buildings: a small office, a classroom and an industrial workshop. The investigation covers five U.S. climatic regions and three different building zones. The study showed that a displacement ventilation system might use more fan energy and less chiller and boiler energy than a mixing ventilation system. The total energy consumption is slightly less with a displacement ventilation system. The displacement ventilation system requires a larger air-handling unit and a smaller chiller than the mixing ventilation system does. The first costs are lower for displacement ventilation if the system is applied in the core region of a building. In the perimeter zones, the displacement ventilation system needs a separate heating system, and the first costs are slightly higher.