Traditional ventilation (or mixed-flow) systems in commercial building are designed to uniformly dilute the entire volume of air in a room or space. By contrast, displacement ventilation (DV) systems rely on the concept of air stratification. A DV system delivers fresh, cooled air at low velocities close to the floor of the room. As this air both heats and becomes polluted by internal sources, it gradually rises to the top of the room where it is extracted.
DV purports to reduce power and energy use as well as significantly improve indoor air quality. More specifically:
Unfortunately, the majority of studies on DV are based on computer simulations with varying results. For example, reported energy savings from one group of studies range from a reduction in total energy use of up to 60 percent to an increase of up to 12 percent (Emmerich and McDowell). As a result, knowledge of the true energy benefits of DV suffers from a striking lack of field-based research on actual buildings, especially in heating dominated climates.
The goal of this CARD grant awarded to Sustainable Engineering Group LLC in 2013 is to conduct a field study to evaluate the power and energy savings potential of DV technology in Minnesota climate conditions, and to determine the significant impediments to its acceptance in the marketplace. To accomplish this, the grantee will identify existing Minnesota commercial buildings with DV systems, conduct surveys of building owners, and analyze the energy and performance data from these buildings. A total of 15 to 30 buildings will be included in the study. In addition, Sustainable Engineering will conduct a second survey among at least 30 local architects and engineers to determine attitudes and market awareness towards DV.