Air curtain effectiveness rating based on aerodynamics

Abstract

An air curtain installed at a building entrance acts as a barrier against infiltration/exfiltration of airflow between the outdoor environment and the indoor space. Several factors may affect air curtain performance, including air discharge velocity, angle, door height and width, and indoor and outdoor conditions. The current methodological standards/codes evaluate air curtain performance based on 1). aerodynamics performance characterization through the measurements of the jet velocity distribution and degradation, and 2). the laboratory measurements of their effectiveness in terms of blocking infiltration/exfiltration rates with/without air curtains under different operating conditions, i.e. pressure difference across doors. The 1st method is easier to conduct but cannot directly evaluate the effectiveness of an air curtain in reducing infiltration/exfiltration. The 2nd method can evaluate each specific unit, though the tests are often prohibitively costly and time-consuming. This study developed a new cost-effective method to assess the aerodynamic performance of an air curtain with respect to its capability of reducing infiltration/exfiltration. This method was demonstrated by a case study and validated against previous experimental data. The new method was found to be more efficient and cost-effective for various air curtain products and installation scenarios, as compared to existing methods.