# Triple Validation of Calibrated Building Energy Models with Different Air Infiltration Values
## 1 Introduction
### Context and Background Work
Given the challenges in selecting suitable infiltration or multi-zone airflow models (e.g., using EnergyPlus or TRNSYS) and determining which experimental methods to use (e.g., wind tunnel, pressure measurement, bluer door test, and tracer gas test), the authors provide guidelines and practical insights for selecting appropriate infiltration and airflow models in BES. In addition, air infiltration is highly sensitive to multiple factors, including building age, volume, height, climate, floor level, and individual apartment characteristics. These sensitivities are influenced by interactions between driving forces for airflow and leakage distribution patterns [16; 17]. The most common in situ tests for measuring infiltration are the bluer door test, which measures the average infiltration rate at 50 Pa [18], and the tracer gas test, which determines the air change rate at normal pressure conditions [19]. [PERSON] et al. found that, although their bluer door test showed uniform air tightness values, the air exchange rates from their tracer gas tests varied significantly due to outdoor wind conditions, with the ratio between these values ranging from <20 to >100 [20]. This variability suggests that the constant value from the bluer door test is not suitable for detailed simulations requiring high-time variation. Nevertheless, results from both tests can be directly incorporated into BEMs. For instance, models that use EnergyPlus (E\({}^{+}\)) as a calculation engine can apply any of three available empirical infiltration models:  
* ZoneInfiltration:DesignFlowRate (hereafter referred to as DFR, is based on the work developed by [PERSON] and [PERSON] [21]): \[I=\Big{(}I_{design}\Big{)}(F_{sch})\Big{[}A+B|(T_{zone}-T_{\_}{\_}{\_}{\_}{ \_}{obs})|+C(WS)+D\Big{(}WS^{2}\Big{)}\Big{]}\] (1) where, in this study, \(I_{\_}{design}=\) is the design infiltration rate in air changes/hour;\(F_{sch}\) = is a value from a user-defined schedule; A = is the constant term coefficient, dimensionless; B = is the temperature term coefficient in \(1/^{\circ}\)C; \(T_{zone}\) and \(T_{adb}\) = temperatures in \({}^{\circ}\)C, the absolute difference in dry-bulb temperature between the average zone temperature and the average outdoor temperature; C = is the velocity term coefficient in s/m; \(WS\) = is the wind speed in m/s; D = is the velocity squared term coefficient in s\({}^{2}\)/m\({}^{2}\). The constant air change rate at 50 Pa can be input into the BEM using the \(I_{design}\) value of the DFR model. All other coefficients (A, B, C, and D) should be set to 1, 0, 0, and 0, respectively. * ZoneInfiltration:FlowCoefficient (referred to as IFC, is based on the AIM-2 model by [PERSON] [22]): \[I=(F_{sch})\sqrt{(cC_{s}\Delta T^{n})^{2}+\left(cC_{w}(s\times WS)^{2n}\right) ^{2}}\] (2) where \(F_{Sch}\) is a value from a user-defined schedule; \(c\) is the flow coefficient in m\({}^{3}/(\)sPa\({}^{n})\); \(C_{s}\) is the coefficient for stack-induced infiltration in \((\)Pa\(/\)K\()^{n}\); \(\Delta T\) is the absolute difference in dry-bulb temperature between the average zone temperature and the average outdoor temperature in \({}^{\circ}\)C; \(n\) is the pressure exponent; \(C_{w}\) is the coefficient for wind-induced infiltration in \((\)Pa\({}^{2}\)/m\({}^{2})^{n}\); \(s\) is the shelter factor; \(WS\) is the local wind speed in m/s. * ZoneInfiltration:EffectiveLeakageArea (referred to as ELA, is based on an ASTM Standard E7/9 effective leakage area calculation [23].