The study conducted by Yuill in 1996 [5] on the impact of use of automatic doors and the infiltration reduction of vestibules is one of the most cited up to this day。 Based on experiments and field observations, Yuill [5] developed an empirical model (Eq。 (1)) in the form of orifice equation to estimate the infiltration rates through single and vestibule doors。 Yuill developed average discharge coef- ficients for the doors by piding their opening cycle in four main

sections (sections a to d in Eq。 (1)) which vary based on the door usage frequency [5,7]。 If the pressure difference across a door is known, these coefficients can then be used in the orifice equation to estimate air infiltration rates through building entrances。 In this paper, we refer an entrance with vestibule to “a vestibule door”, and without vestibule to “a single door”  [7]。

。 26P

Rp is the pressure factor obtained from ASHRAE and based on the outdoor temperature and building height [8], and 6P is the pressure difference across the door。

In the original study by Yuill [5] and in ASHRAE publication [8] where these design charts appear, it is stated that if the assump- tions regarding the Rp do not hold, the calculation of the pressure difference across the door should be completed by considering the stack and wind pressures in more details。 Yuill [5,7] also suggested using of airflow network models for more realistic estimations of the pressure difference across the door。 In these simulations, the door can experience flow in two directions, infiltration or exfiltra- tion。 Despite the wide use of door coefficients suggested by Yuill [5] in many studies [6,9–14], none of these subsequent studies experimentally verified the coefficients proposed, especially for the exfiltration flow region。

Building energy simulation has become a common tool in mea- suring the impact of various envelope related characteristics on energy use。 The U。S。 Pacific Northwest National Laboratory (PNNL) published a report where they investigated the energy saving impact of vestibules in commercial reference buildings [4]。 The ref- erence building models of the national building stock, which were developed by a number of national laboratories in collaboration with the U。S。 DOE, are used in the development, assessment, and research of new technologies and codes (DOE and PNNL use these reference models for the development of new ASHRAE Standard

90。1 Versions) [15]。 These reference models are available online as input files for the widely used energy simulation program Energy- Plus [16]。 In their study [4], PNNL used EnergyPlus [16] to conduct simulations for 12 reference building models in 16 climate zone locations。 The study [4] used the models proposed by Yuill [5,8] to calculate the infiltration rates through single and vestibule doors

Q = CDaveATh

(1)

p

in buildings that have building specific door usage and operation schedules。 To quantify the pressure across the doors in their study,

Where CDave  is the overall average discharge  coefficient,

CDaa + CDbb + CDcc + CDdd

PNNL used the Rp factor charts in ASHRAE [8] while adding the assumption that, for all the buildings in all climate zone (which

vary from arctic to very hot climate), the outdoor temperature is

CDave =

a + b

+ c + d

constant at 16 ◦C [4]。 The PNNL study used the pressure coefficient (Rp) to consider pressure difference (6P) across the door and a sen-

CD,section(a,b,c,d)  is the average discharge coefficient for each door

operation section,

a, b, c & d are the time period (in s) for each door operation section based on field observations

Th is the door usage per hour (h/h), A is the full door size (m2),