Evaluating the different boundary conditions to simulate airflow and heat transfer in Double-Skin Facade

Abstract

The CFD simulation accuracy mostly depends on the appropriate setting of boundary conditions and numerical simulation parameters. This study shows the influence of two types of boundary condition settings on the CFD simulation results of Double-Skin Façade (DSF) for a specific problem. These two boundary settings are the constant temperature on the DSF surfaces called Boundary A, and Boundary B is defined via solar radiation using the Discrete Ordinate radiation Model (DOM). The paper verified both the numerical simulations using the experimental data. Comparing the numerical results of two types of boundaries with experimental data shows that both cases underestimated the values lower than 5.2 K and 0.1 m/s for the temperature and velocity respectively at the regarded measured points. Boundary A gives more accurate temperature prediction results while Boundary B shows velocity magnitude closer to the measurements in the middle height of the cavity; the average temperature and velocity differences between the two boundary types are 0.6 K and, 0.003 m/s respectively which are negligible. Finally, the selection of boundary conditions depends on study purposes, however, when the DSF is equipped with blinds and if there is not enough data in hand but the exact value of solar irradiation, using the Boundary B approach is suggested; it can provide reasonable results associated with multi-type of thermal boundary conditions at the same time. Furthermore, if the goal is to investigate the flow pattern in the DSF, Boundary B is argued to perform better than the constant temperature boundary condition.

Efficient Shading Device as an Important Part of Daylightophil Architecture; a Designerly Framework of High-Performance Architecture for an Office Building in Tehran

“…On average we find that every month of full lockdown reduced the demand by 20% on average, or over 1.5% on an annual basis [5]. Therefore, focusing on methods to optimize the energy efficiency and promoting sustainability in the building's component while considering the quality of indoor spaces has been one of the trend topics among researchers [6][7][8][9][10][11][12][13]. In Iran, artificial lighting is reported to contribute up to 25% of electricity consumption in office buildings [14].…”

Passive Strategies for Building Retrofitting: Performances Analysis and Incentive Policies for the Iranian Scenario

“…The numerical analysis results highlighted a reduction of the energy consumption of between 7.9% and 14.8%, while the operational CO 2 emission was cut down by a maximum of 17% [30]. In [35], the authors provided information for developing and selecting an appropriate SS facade system simulation using CFD, verifying the effect of using two types of boundary conditions: (i) the surfaces' temperatures and (ii) the outdoor conditions correlated to the solar radiation. The authors highlight how the modeling of the outdoor conditions allows studying complex geometries, particularly when focusing on passive approaches.…”

“…Several types of research have been performed in the last year to evaluate the effectiveness of SS facade systems in the Iranian climate [27][28][29][30]35,36]. In particular, in Hashemi et al [27], a building with a SS facade system was monitored for two weeks during summer and two weeks during winter in the hot arid climate of Iran to observe the behaviors of the facade both in hot and cold conditions.…”

“…The literature review [17,20,23,[27][28][29][30][31][32][33][34][35][36] highlighted a number of benefits achievable using the SS facade system. In addition, the part of the literature review related to the Iranian climate [27][28][29][30]35,36] highlighted that: (i) all the analyzed researches are focused on temperate climates, (ii) glass is usually used as SS material, and (iii) only one research evaluated the reduction of carbon dioxide emissions.…”

“…The literature review [17,20,23,[27][28][29][30][31][32][33][34][35][36] highlighted a number of benefits achievable using the SS facade system. In addition, the part of the literature review related to the Iranian climate [27][28][29][30]35,36] highlighted that: (i) all the analyzed researches are focused on temperate climates, (ii) glass is usually used as SS material, and (iii) only one research evaluated the reduction of carbon dioxide emissions. Therefore, the literature review related to the usage of the SS facade systems in Iran [27][28][29][30]35,36] shows gaps regarding: (i) the performance investigation under cold climate and hot climate, (ii) the use of lightweight materials (such as the PVC-coated polyester fabric [38] investigated in this research), (iii) the environmental effects of these systems and (iv) their economic impacts.…”