Title

Session

Authors

Abstract

Air curtains have been widely used on building entrances as a barrier to reduce energy losses due to infiltration/exfiltration while still permitting unobstructed passage of pedestrian traffic. Many building energy codes are published that prescribe the requisite for energy efficient designs. These codes address building entrances that separate conditioned space from the exterior with a requirement that they shall be protected with an enclosed vestibule.
Recent studies examine and validate the performance or effectiveness of air curtains at a macro or whole building perspective and compare that to vestibules. The studies illustrate that several factors impact air curtain effectiveness including air discharge velocity, angle, door height and width, indoor and outdoor pressure conditions. Existing test methods (and associated standards/codes) evaluate the effectiveness based on
1.) either the aerodynamics characterization of air curtain through the measurements of air curtain jet velocity distribution and degradation,
2.) or the measurements of infiltration/exfiltration rates with/without the air curtain under different operating conditions, i.e. pressure difference across the door.
The 1st method is easier to be conducted but is not directly related to evaluating the capability of reducing infiltration/exfiltration whereas the 2nd method can do so by testing each specific unit, which is often costly, time-consuming and sometimes impractical. Therefore, a relatively simpler method is required to combine both methods for the evaluation of air curtain effectiveness during its design, selection and operation.
This study aims to develop such a calculation method to relate the aerodynamics performance test method in ANSI/AMCA Standard 220-05 or ISO 27327-1:2009 directly to evaluating the air curtain’s capability of reducing infiltration/exfiltration rates. It is proposed that an air curtain discharge be separated into several sub-sections to consider the diversity of the discharge velocity along the air curtain width. Case studies are provided for the demonstration of the whole process. A validation study using the previous experimental results is also conducted. In comparison to the existing effectiveness test methods, the new method is a more feasible solution to various air curtain products and installation scenarios.