a b  s  t r a c  t Article history:Keywords:Air infiltration Entrance doors Vestibules energy savings Experimental validation Airflow and energy simulations

Building entrance doors are a major source of air infiltration and energy loss in commercial buildings。 Previous studies have calculated entrance doors air infiltration and energy saving potential of vestibules with the simplified method which is based on pressure factors。 However, challenges are still faced in estimating the pressure difference and the resultant infiltration rates across doors as well as validating the used airflow coefficients under different flow conditions。 In this paper, an experimental study is used to validate the airflow coefficient for a fully open single door under both infiltration and exfiltration conditions。 The study presents four methods for modeling air infiltration across automatic single and vestibule doors for two reference building models: two methods use the pressure factors and the two others are based on airflow simulations。 Energy simulations are then conducted using the air infiltration rates obtained from each method。 The results revealed that the design methods overestimate the pressure difference across doors, the air infiltration rates as well as the vestibule savings potentials in comparison to the simulation methods。 In conclusion, airflow simulations were found to provide more realistic estimates of pressure differences and infiltration rates across entrance doors when compared to the widely-used design methods。76298

1。   Introduction

The building sector (residential, commercial and institutional) in the United States was reported to account  for approximately 40% of primary energy usage nationwide [1]。 A study on U。S。 office buildings  indicated  that,  in  modern  well-constructed  and   insu-

Abbreviations: ASHRAE, American Society of Heating Refrigerating and Air- Conditioning Engineer; Design Method, Design infiltration rates calculation   using

the Rp factor at 16◦ C for the whole year; DB, Dry bulb temperature; Fully open door, Door open at 90◦ ; LG, Large store (in the strip mall reference building model); NIST,

National Institute of Standards and Technology; RH, Relative Humidity; Seasonal CONTAM Method, Infiltration rates obtained using airflow simulation for the build- ing with the design conditions of climate zones for two design conditions (summer & winter); Seasonal design method, Design infiltration rates calculation using the Rp factor for two design conditions (summer & winter); Single door, Double swing doors opening out (without vestibule); SM, Small store (in the strip mall reference build- ing model); US。 DOE (DOE), United States Department of Energy; Vestibule door, Vestibule with double swing doors opening out (2 set of double swing doors); Yearly CONTAM method, Infiltration rates obtained using yearly whole building airflow simulations。

∗    Corresponding  author。

E-mail addresses: leon。wang@concordia。ca, lzwang@gmail。com (L。    Wang)。

lated buildings, air infiltration can be responsible for up to 25% of the building heating loads [2]。 ASHRAE defines air infiltration as the uncontrolled inward leakage of outdoor air into building caused by the existence of a pressure deferential across the var- ious building enclosure elements [3]。 Entrance doors, which in commercial buildings are often automatic doors, are generally one of the major sources of air infiltration especially when they are used frequently [4,5]。 Based on the available studies [5,6] regard- ing automatic doors, current building energy codes (such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers – ASHRAE Standard 90。1–Energy Standard for Buildings Except Low-Rise Residential Buildings [3], as well as the Interna- tional Energy Conservation Code) require entrances to be equipped with vestibules (vestibule doors) in most commercial buildings to reduce air infiltration。