Estimating tall building infiltration at main entryway

Abstract

The current industry standard method for estimating tall building entryway infiltration rates in cold climates is found in ASHRAE Handbook—Fundamentals (2013). This method was developed in ASHRAE Research Project (RP) 763 (Yuill 1996). In the comparison of an example calculation provided in RP-763 (Yuill 1996) and reproduced in 2013 ASHRAE Handbook Fundamentals (2013) with simulation results for the same example using various building configurations, the multi-node airflow analysis tool simulations consistently calculated significantly lower flow rates than predicted by the RP-763 (Yuill 1996) method (Whitehead and Frisque 2012). Addressing the large over-prediction of infiltration rates resulting from the estimation method currently published in the ASHRAE Handbook—Fundamentals (2013), this article proposes a new method to estimate this infiltration rate. The main difference of this new method (which we refer to as limiting area method [LAM]) is that it takes into account the smallest openings in the flow path limiting airflow. Comparison of results using the LAM to those from the previous simulations show that it is much closer to the more detailed simulation calculations, with estimates ranging from 92% to 134% of simulation results for the building examples considered.