To summarize the literature review, four different methods have been available for modeling building entrance infiltration for build- ing energy simulation  purposes:

1。 Design infiltration calculation method (hereafter, Design Method) – Following the process proposed by ASHRAE [8] and used by the PNNL’s study for the vestibule requirements of ASHARE 90。1 [4], the design pressure difference across the door is calculated for each building based on the Rp factor at 16 ◦C and used in Eq。 (2)。 The data obtained using this method is used as the baseline for the study considering it is the method often used by PNNL  [15]。

2。 Seasonal design infiltration calculation method (hereafter, Seasonal Design Method)– Similar to the Design Method, the Rp factor is calculated and used。 However, the climate specific winter and summer design temperatures are used to calculate the pressure differences across the doors of each climate zone  location。

3。 Seasonal design infiltration simulation method (hereafter, sea- sonal CONTAM method): using the airflow building models [22] for the simulation software CONTAM [24], the seasonal door infiltration rates for each door type in both buildings is obtained by simulations using the design conditions。 Only the door infil- tration rates from the airflow simulations are used as input in the energy model to replace the existing door  infiltrations

4。 Yearly infiltration simulation method (hereafter, Yearly CONTAM Method), similar to the Seasonal CONTAM Method, yearly tran- sient airflow simulations are used。 The hourly infiltration rates of the whole building in the different climate zones are exported and input in the energy  model。

It is important to note that methods 1 and 2 focus only on the entrance door and are based on calculations while methods 3 and 4 use airflow simulations which consider all the building parame- ters and climate conditions。 Although the four methods use Yuill’s model for single and vestibule door infiltration (Eq。 (2)), the main difference between the presented methods lay in the calculation of pressure difference across the door: in methods 1 and 2 the pres- sure factor, Rp, is used to calculate the pressure difference, and for methods 3 and 4 the pressure difference across the door is obtained by CONTAM simulations, which take into account various building and weather parameters [22]。 The validity of the CONTAM  simula-

tions of the DOE reference buildings can be further found from the study by Ng et al。 [22]。

This paper compares four different methods for calculating building entrance air infiltration rates。 It also investigates the cor- responding impact of these methods on whole building annual energy performance using EnergyPlus simulations。 Since Yuill’s infiltration coefficients were developed using chamber depressur- izations mostly for door infiltration conditions [5], for the airflow simulations in this study of both infiltration and exfiltration, the paper  presents  an  experimental  verification  to  confirm  the  sin-

gle fully open (90◦) door airflow coefficients suggested by Yuill  [1]

under negative infiltration (exfiltration) condition。 In Yuill’s study, he first measured steady-state flow discharge coefficients  with- out considering door opening and people movement for different door opening angles, and then in the second step, he proposed a method to consider these effects using an idea of effective opening area during a full opening/closing cycle of door。 For Yuill’s model, the HVAC on/off effect, if any, will be reflected in the pressure difference during the calculation of infiltration/exfiltration rates。 Therefore, in both Yuill’s and this study’s experiments, there is no need to consider them。 In this study, we focus on his first step (without door movement and people) and try to verify his flow coef- ficients in the negative flow region (exfiltration)。 For this purpose, the door movement, people and HVAC are not required to be cap- tured in the experimentation。 Comparisons are made between the air infiltration rates and the end use energy consumption obtained through each method。 The paper uses the ASHRAE 90。1-2013 strip mall and outpatient healthcare reference building models [27] and the corresponding airflow network models [22] to conduct energy and airflow simulations for the buildings with single and vestibule doors in three climate zone locations。 In addition, the sensitivity of the results to different aspects such as the door usage frequency and door size are also presented。