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CFD simulation of wind and thermal-induced ventilation flow of a roof cavity

Abstract

The hygrothermal performance of a ventilated roof cavity is greatly affected by the airflow passing through it. This ventilation flow is mainly driven by the wind pressure difference between openings and the thermal-induced buoyancy. However, the wind effect is not well understood as it is often neglected in previous studies. The present study investigates the properties of such airflows, including the flow pattern, flow regime, and flow rate, using a CFD method. The target building is a large-span commercial building with a low-pitched roof. To study the wind-induced airflows, the onset atmospheric boundary layer wind flow was modelled, and the results were compared with the site-measured data recorded in the literature. To study the thermal-induced buoyancy effects, a roof cavity model found in the literature with experimental data was adopted. The findings show that the flow pattern in the roof cavity varied with the airflow driven factors. The flow separation at the windward eave inlet of the thermally induced flows are more pronounced compared with those of the wind-induced flows. Furthermore, the wind-induced airflows can generate around two times more ventilation flow rate through the roof cavity compared to the thermal-induced airflow. The findings indicate that wind-induced ventilation flows are the dominant factor of the roof cavity ventilation in a large-span, low-pitched building.

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References

  • Almand R, London R (2020). Airtight buildings causing moisture issues. Ministry of Business, Innovation & Employment.

  • Alsailani M, Montazeri H, Rezaeiha A (2021). Towards optimal aerodynamic design of wind catchers: Impact of geometrical characteristics. Renewable Energy, 168: 1344–1363.

    Article  Google Scholar 

  • Alzwayi AS, Paul MC (2013). Effect of width and temperature of a vertical parallel plate channel on the transition of the developing thermal boundary layer. International Journal of Heat and Mass Transfer, 63: 20–30.

    Article  Google Scholar 

  • ANSYS-CFX (2020). ANSYS Fluent and CFX 2020 R1. Available at https://www.ansys.com/blog/ansys-2020-r1

  • AS/NZS 1170.2 (2011). Structural design actions. Wind actions: Standards Australia.

  • ASHRAE (1993). ASHRAE Handbook of Fundamentals. Atlanta, GA, USA: American Society of Heating, Refrigerating and Air-Conditioning Engineers.

    Google Scholar 

  • Bassett MR, McNeil S (2005). The theory of ventilation drying applied to New Zealand cavity walls. Paper presented at the Institution of Refrigeration, Heating and Air Conditioning Engineers, Nelson, New Zealand

  • Bianco V, Diana A, Manca O, et al. (2017). Thermal behavior evaluation of ventilated roof under summer and winter conditions. International Journal of Heat and Technology, 35: S353–S360.

    Article  Google Scholar 

  • Bianco V, Diana A, Manca O, et al. (2018). Numerical investigation of an inclined rectangular cavity for ventilated roofs applications. Thermal Science and Engineering Progress, 6: 426–435.

    Article  Google Scholar 

  • Biwole PH, Woloszyn M, Pompeo C (2008). Heat transfers in a double-skin roof ventilated by natural convection in summer time. Energy and Buildings, 40: 1487–1497.

    Article  Google Scholar 

  • Blocken B, Stathopoulos T, Carmeliet J (2007). CFD simulation of the atmospheric boundary layer: wall function problems. Atmospheric Environment, 41: 238–252.

    Article  Google Scholar 

  • Bortoloni M, Bottarelli M, Piva S (2017). Summer thermal performance of ventilated roofs with tiled coverings. Journal of Physics: Conference Series, 796: 012023.

    Google Scholar 

  • Bottarelli M, Zannoni G, Bortoloni M, et al. (2017). CFD analysis and experimental comparison of novel roof tile shapes. Propulsion and Power Research, 6: 134–139.

    Article  Google Scholar 

  • BS 6399 (1996). Loading for buildings. Code Of Practice For Dead And Imposed Loads. British Standard.

  • Bunkholt NS, Säwén T, Stockhaus M, et al. (2020). Experimental study of thermal buoyancy in the cavity of ventilated roofs. Buildings, 10: 8.

    Article  Google Scholar 

  • Celik IB, Ghia U, Roache PJ, et al. (2008). Procedure for estimation and reporting of uncertainty due to discretization in CFD applications. Journal of Fluids Engineering, 130: 078001.

    Article  Google Scholar 

  • Cengel YA, Cimbala JM (2004). Fluid Mechanics: Fundamentals and Applications. New York: McGraw-Hill.

    Google Scholar 

  • Chami N, Zoughaib A (2010). Modeling natural convection in a pitched thermosyphon system in building roofs and experimental validation using particle image velocimetry. Energy and Buildings, 42: 1267–1274.

    Article  Google Scholar 

  • Ciampi M, Leccese F, Tuoni G (2003). Ventilated facades energy performance in summer cooling of buildings. Solar Energy, 75: 491–502.

    Article  Google Scholar 

  • De With G, Cherry N, Haig J (2009). Thermal benefits of tiled roofs with above-sheathing ventilation. Journal of Building Physics, 33: 171–194.

    Article  Google Scholar 

  • El Ahmar S, Battista F, Fioravanti A (2019). Simulation of the thermal performance of a geometrically complex Double-Skin Facade for hot climates: EnergyPlus vs. OpenFOAM. Building Simulation, 12: 781–795.

    Article  Google Scholar 

  • Falk J, Sandin K (2013). Ventilated rainscreen cladding: Measurements of cavity air velocities, estimation of air change rates and evaluation of driving forces. Building and Environment, 59: 164–176.

    Article  Google Scholar 

  • Franke J, Hirsch C, Jensen A, et al. (2004). Recommendations on the use of CFD in wind engineering. In: Proceedings of the International Conference on Urban Wind Engineering and Building Aerodynamics.

  • Gagliano A, Patania F, Nocera F, et al. (2012). Thermal performance of ventilated roofs during summer period. Energy and Buildings, 49: 611–618.

    Article  Google Scholar 

  • Gargallo-Peiró A, Avila M, Owen H, et al. (2018). Mesh generation, sizing and convergence for onshore and offshore wind farm Atmospheric Boundary Layer flow simulation with actuator discs. Journal of Computational Physics, 375: 209–227.

    MathSciNet  Article  Google Scholar 

  • Gullbrekken L, Uvsløkk S, Kvande T, et al. (2018). Wind pressure coefficients for roof ventilation purposes. Journal of Wind Engineering and Industrial Aerodynamics, 175: 144–152.

    Article  Google Scholar 

  • Irtaza H, Beale RG, Godley MHR, et al. (2018). Comparison of wind pressure measurements on Silsoe experimental building from full-scale observation, wind-tunnel experiments and various CFD techniques. International Journal of Engineering, Science and Technology, 5: 28–41.

    Article  Google Scholar 

  • ISO13788:2012 (2012). Hygrothermal performance of building components and building elements. Internal surface temperature to avoid critical surface humidity and interstitial condensation. Calculation methods.

  • Janssens A, Hens H (2007). Effects of wind on the transmission heat loss in duo-pitched insulated roofs: A field study. Energy and Buildings, 39: 1047–1054.

    Article  Google Scholar 

  • Kovac M, Vojtus J (2015). Analysis of air velocity, moisture and thermal regime in an air gap of a double-shell roof. Energy Procedia, 78: 759–764.

    Article  Google Scholar 

  • Lee S, Park SH, Yeo MS, et al. (2009). An experimental study on airflow in the cavity of a ventilated roof. Building and Environment, 44: 1431–1439.

    Article  Google Scholar 

  • Li D, Zheng Y, Liu C, et al. (2016). Numerical analysis on thermal performance of naturally ventilated roofs with different influencing parameters. Sustainable Cities and Society, 22: 86–93.

    Article  Google Scholar 

  • Li J, Tong L, Wu J, et al. (2019). Numerical investigation of wind pressure coefficients for photovoltaic arrays mounted on building roofs. KSCE Journal of Civil Engineering, 23: 3606–3615.

    Article  Google Scholar 

  • Matour S, Garcia-Hansen V, Omrani S, et al. (2021). Wind-driven ventilation of Double Skin Facades with vertical openings: Effects of opening configurations. Building and Environment, 196: 107804.

    Article  Google Scholar 

  • Menter FR (1994). Two-equation eddy-viscosity turbulence models for engineering applications. AIAA Journal, 32: 1598–1605.

    Article  Google Scholar 

  • Menter FR, Langtry RB, Likki SR, et al. (2006). A correlation-based transition model using local variables—part I: model formulation. Journal of Turbomachinery, 128: 413.

    Article  Google Scholar 

  • Mi H (2012). Research on characteristic parameters of turbulente flow field around a square cross-sectioned bluff body. PhD Thesis, Harbin Engineering University, China. (in Chinese)

    Google Scholar 

  • Moran P, Hoxey RP (1979). A probe for sensing static pressure in two-dimensional flow. Journal of Physics E: Scientific Instruments, 12: 752–753.

    Article  Google Scholar 

  • Pak R, Ocak Z, Sorgüven E (2018). Developing a passive house with a double-skin envelope based on energy and airflow performance. Building Simulation, 11: 373–388.

    Article  Google Scholar 

  • Richards PJ, Hoxey RP (1992). Computational and wind tunnel modelling of mean wind loads on the Silsoe structures building. Journal of Wind Engineering and Industrial Aerodynamics, 43: 1641–1652.

    Article  Google Scholar 

  • Richards P, Hoxey R (1993). Appropriate boundary conditions for computational wind engineering models using the k-ϵ turbulence model. Journal of Wind Engineering and Industrial Aerodynamics, 46–47: 145–153.

    Article  Google Scholar 

  • Richards PJ, Norris SE (2015). Appropriate boundary conditions for a pressure driven boundary layer. Journal of Wind Engineering and Industrial Aerodynamics, 142: 43–52.

    Article  Google Scholar 

  • Richards PJ, Norris SE (2019). Appropriate boundary conditions for computational wind engineering: Still an issue after 25 years. Journal of Wind Engineering and Industrial Aerodynamics, 190: 245–255.

    Article  Google Scholar 

  • Richardson GM, Surry D (1994). The Silsoe structures building: Comparison between full-scale and wind-tunnel data. Journal of Wind Engineering and Industrial Aerodynamics, 51: 157–176.

    Article  Google Scholar 

  • Rupp S (2016). Passive roof ventilation. Build, 152: 54–55.

    Google Scholar 

  • Rupp SH, McNeil S, Plagmann M, Overton G (2021). Hygrothermal characteristics of cold roof cavities in new zealand. Buildings, 11: 334.

    Article  Google Scholar 

  • Safaei Pirooz AA, Flay RGJ (2018). Comparison of speed-up over hills derived from wind-tunnel experiments, wind-loading standards, and numerical modelling. Boundary-Layer Meteorology, 168: 213–246.

    Article  Google Scholar 

  • Säwén T, Stockhaus M, Hagentoft CE, et al. (2021). Model of thermal buoyancy in cavity-ventilated roof constructions. Journal of Building Physics, https://doi.org/10.1177/1744259120984189

  • Sharifi A, Yamagata Y (2015). Roof ponds as passive heating and cooling systems: A systematic review. Applied Energy, 160: 336–357.

    Article  Google Scholar 

  • Straube J, Burnett E (1995). Vents, ventilation drying, and pressure moderation. A report prepared for Canada mortgage and housing corporation 1995 project manager: Pierre-Michel busque.

  • Straube JF (1998). Moisture control and enclosure wall systems, PhD Thesis, University of Waterloo, Canada.

    Google Scholar 

  • Susanti L, Homma H, Matsumoto H, et al. (2010). Numerical simulation of natural ventilation of a factory roof cavity. Energy and Buildings, 42: 1337–1343.

    Article  Google Scholar 

  • Susanti L, Homma H, Matsumoto H (2011). A naturally ventilated cavity roof as potential benefits for improving thermal environment and cooling load of a factory building. Energy and Buildings, 43: 211–218.

    Article  Google Scholar 

  • Tominaga Y, Mochida A, Yoshie R, et al. (2008). AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings. Journal of Wind Engineering and Industrial Aerodynamics, 96: 1749–1761.

    Article  Google Scholar 

  • Tominaga Y, Akabayashi SI, Kitahara T, et al. (2015). Air flow around isolated gable-roof buildings with different roof pitches: Wind tunnel experiments and CFD simulations. Building and Environment, 84: 204–213.

    Article  Google Scholar 

  • Tong S, Li H (2014). An efficient model development and experimental study for the heat transfer in naturally ventilated inclined roofs. Building and Environment, 81: 296–308.

    Article  Google Scholar 

  • Tosun I, Uner D, Ozgen C (1988). Critical Reynolds number for Newtonian flow in rectangular ducts. Industrial & Engineering Chemistry Research, 27: 1955–1957.

    Article  Google Scholar 

  • Vanpachtenbeke M, Langmans J, van den Bulcke J, et al. (2017). On the drying potential of cavity ventilation behind brick veneer cladding: A detailed field study. Building and Environment, 123: 133–145.

    Article  Google Scholar 

  • Villi G, Pasut W, De Carli M (2009). CFD modelling and thermal performance analysis of a wooden ventilated roof structure. Building Simulation, 2: 215–228.

    Article  Google Scholar 

  • Wang M, Hou J, Hu Z, et al. (2021). Optimisation of the double skin facade in hot and humid climates through altering the design parameter combinations. Building Simulation, 14: 511–521.

    Article  Google Scholar 

  • Wheather Channel(2021). The Weather Channel. Available at https://weather.com/en-NZ/weather/today/l/a923c5e150d89346b6976561f561bd5a1e5d04bd21f95ff5fa5f62d9df22a03b

  • Yang S, Cannavale A, Prasad D, et al. (2019). Numerical simulation study of BIPV/T double-skin facade for various climate zones in Australia: Effects on indoor thermal comfort. Building Simulation, 12: 51–67.

    Article  Google Scholar 

  • Yau YH, Lian YC (2016). A computational fluid dynamics study of the effects of buoyancy on air flow surrounding a building. Building Services Engineering Research and Technology, 37: 257–271.

    Article  Google Scholar 

  • Zaki A, Richards P, Sharma R (2019). Analysis of airflow inside a two-sided wind catcher building. Journal of Wind Engineering and Industrial Aerodynamics, 190: 71–82.

    Article  Google Scholar 

  • Zheng X, Montazeri H, Blocken B (2020). CFD simulations of wind flow and mean surface pressure for buildings with balconies: Comparison of RANS and LES. Building and Environment, 173: 106747.

    Article  Google Scholar 

  • Zheng X, Montazeri H, Blocken B (2021). CFD analysis of the impact of geometrical characteristics of building balconies on near-facade wind flow and surface pressure. Building and Environment, 200: 107904.

    Article  Google Scholar 

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Acknowledgements

The first author appreciates the funding support from the Fletcher Steel Limited and Callaghan Innovation, and all the authors would like to acknowledge New Zealand eScience Infrastructure (NESI) for providing the HPC resources.

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Contributions

Wei Li: conceptualization, methodology, formal analysis, writing — original draft. Alison Subiantoro: supervision, writing - review and editing. Ian McClew: supervision, writing - review and editing. Rajnish N. Sharma: supervision, writing - review and editing.

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Correspondence to Wei Li.

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Li, W., Subiantoro, A., McClew, I. et al. CFD simulation of wind and thermal-induced ventilation flow of a roof cavity. Build. Simul. 15, 1611–1627 (2022). https://doi.org/10.1007/s12273-021-0880-x

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  • DOI: https://doi.org/10.1007/s12273-021-0880-x

Keywords

  • ventilated roof cavity
  • CFD simulation
  • atmospheric boundary layer
  • thermal-induced buoyancy