Hospital ventilation simulation for the study of potential exposure to contaminants

Abstract

Airflow and ventilation are particularly important in healthcare rooms for controlling thermo-hygrometric conditions, providing anaesthetic gas removal, diluting airborne bacterial contamination and minimizing bacteria transfer airborne. An actual hospitalization room was the investigate case study. Transient simulations with computational fluid dynamics (CFD), based on the finite element method (FEM) were performed to investigate the efficiency of the existing heating, ventilation and air-conditioning (HVAC) plant with a variable air volume (VAV) primary air system. Solid modelling of the room, taking into account thermo-physical properties of building materials, architectural features (e.g., window and wall orientation) and furnishing (e.g., beds, tables and lamps) arrangement of the room, inlet turbulence high induction air diffuser, the return air diffusers and two patients lying on two parallel beds was carried out. Multiphysics modelling was used: a thermo-fluidynamic model (convection-conduction and incompressible Navier-Stokes) was combined with a convection-diffusion model. Three 3D models were elaborated considering different conditions/events of the patients (i.e., the first was considered coughing and/or the second breathing). A particle tracing and diffusion model, connected to cough events, was developed to simulate the dispersal of bacteria-carrying droplets in the isolation room equipped with the existing ventilation system. An analysis of the region of droplet fallout and the dilution time of bacteria diffusion of coughed gas in the isolation room was performed. The analysis of transient simulation results concerning particle path and distance, and then particle tracing combined with their concentration, provided evidence of the formation of zones that should be checked by microclimatic and contaminant control. The present study highlights the fact that the CFD-FEM application is useful for understanding the efficiency, adequacy and reliability of the ventilation system, but also provides important suggestions for controlling air quality, patients’ comfort and energy consumption in a hospital.

References

  1. ASHRAE (1995). ASHRAE Handbook: HVAC Applications, SI Edition. Atlanta, GA: The American Society of Heating, Refrigerating and Air-Conditioning Engineers.

    Google Scholar 

  2. Balaras CA, Dascalaki E, Gaglia A (2007). HVAC and indoor thermal conditions in hospital operating rooms. Energy and Buildings, 39: 454–470.

    Article  Google Scholar 

  3. Balocco C, Liò P (2011). Assessing ventilation system performance in an isolation room. Energy and Buildings, 43: 246–252.

    Article  Google Scholar 

  4. Batchelor GK (2000). An Introduction to Fluid Dynamics. Cambridge, UK: Cambridge University Press.

    Book  Google Scholar 

  5. Brandt C, Hott E, Sohr D, Daschner F, Gastmeier P, Rüden H (2008). Operating room ventilation with laminar airflow shows no protective effect on the surgical site infection rate in orthopedic and abdominal surgery. Annals of Surgery, 248: 695–700.

    Article  Google Scholar 

  6. Chen Q, Srebric J (2001). Simplified diffuser boundary conditions for numerical room airflow model: Final report of RP-1009. Atlanta, GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers.

    Google Scholar 

  7. Chow TT, Yang XY (2003). Performance of ventilation system in a non-standard operating room. Building and Environment, 38: 1401–1411.

    Article  Google Scholar 

  8. COMSOL (2009). http://www.comsol.com.

  9. Cunningham E (1910). On the velocity of steady fall of spherical particles through fluid medium. Proceedings of the Royal Society of London. Series A, 83: 357–365.

    MATH  Google Scholar 

  10. Dascalaki EG, Gaglia AG, Balaras CA, Lagoudi A (2009). Indoor environmental quality in Hellenic hospital operating rooms. Energy and Buildings, 41: 551–560.

    Article  Google Scholar 

  11. Diekmann O, Heesterbeek JAP (2000). Mathematical Epidemiology of Infectious Diseases. Chichester, UK: John Wiley & Sons.

    MATH  Google Scholar 

  12. Farnsworth JE, Goyal SM, Kim SW, Kuehn TH, Raynor PC, Ramak-rishnan MA, Anantharaman S, Tang W (2006). Development of a method for bacteria and virus recovery from heating, ventilation, and air conditioning (HVAC) filters. Journal of Environmental Monitoring, 8: 1006–1013.

    Article  Google Scholar 

  13. Galson E, Guisbond J (1995). Hospital sepsis control and TB transmission. ASHRAE Journal. 37(5):48–52.

    Google Scholar 

  14. Gupta J, Lin CH, Chen Q (2009). Flow dynamics and characterization of a cough. Indoor Air, 19: 517–525.

    Article  Google Scholar 

  15. Huo Y, Haghighat F, Zhang J S, Shaw C Y (2000). A systematic approach to describe the air terminal device in CFD simulation for room air distribution analysis. Building and Environment, 35: 563–576.

    Article  Google Scholar 

  16. ISO 7730 (2005). Moderate thermal environments—Determination of the PMV and PPD indices and specification of the conditions for thermal comfort.

  17. Jiang Y, Su M, Chen Q (2003). Using large eddy simulation to study airflows in and around buildings. ASHRAE Transactions, 109(2): 517–526.

    Google Scholar 

  18. Jiang Y, Zhao B, Li X, Yang X, Zhang Z, Zhang Y (2009). Investigating a safe ventilation rate for the prevention of indoor SARS transmission: An attempt based on a simulation approach. Building Simulation, 2: 281–289.

    Article  Google Scholar 

  19. Kao PH, Yang RJ (2006). Virus diffusion in isolation rooms. Journal of Hospital Infection, 62: 338–345.

    Article  Google Scholar 

  20. Kim S H, Augenbroe G (2009). Ventilation operation in hospital isolation room: a multi-criterion assessment considering organizational behaviour. In: Proceedings of the 11th IBSPSA Conference (pp. 1322–1329), Glasgow, Scotland.

  21. Li A, Liu Z, Zhu X, Liu Y, Wang Q (2010). The effect of air-conditioning parameters and deposition dust on microbial growth in supply air ducts. Energy and Buildings, 42: 449–454.

    Article  Google Scholar 

  22. Li Y, Leung GM, Tang JW, Yang X, Chao C, Lin JH, Lu JW, Nielsen PV, Niu JL, Qian H, Sleigh AC, Su HJ, Sundell J, Wong TW, Yuen PL (2007). Role of ventilation in airborne transmission of infectious agents in the built environment—A multidisciplinary systematic review. Indoor Air, 17: 2–18.

    Article  Google Scholar 

  23. Lim T, Cho J, Kim BS (2010). The predictions of infection risk of indoor airborne transmission of diseases in high-rise hospitals: Tracer gas simulation. Energy and Buildings, 42: 1172–1181.

    Article  Google Scholar 

  24. Marianne T, Perini JM, Lafitte JJ, Houdret N, Pruvot FR, Lamblin G, Slayter HS, Roussel P (1987). Peptides of human bronchial mucus glycoproteins. Size determination by electron microscopy and by biosynthetic experiments. Biochemical Journal, 248: 189–195.

    Article  Google Scholar 

  25. Martini I, Discoli C, Rosenfeld E (2007). Methodology developed for the energy-productive diagnosis and evaluation in health buildings. Energy and Buildings, 39: 727–735.

    Article  Google Scholar 

  26. Memarzadeh F, Manning AP (2002). Comparison of operating room ventilation systems in the protection of the surgical site. ASHRAE Transactions, 108(2): 3–15.

    Google Scholar 

  27. Méndez C, San José JF, Villafruela JM, Castro F (2008). Optimization of a hospital room by means of CFD for more efficient ventilation. Energy and Buildings, 40: 849–854.

    Article  Google Scholar 

  28. Muia KW, Wonga LT, Wub CL, Lai Alvin CK (2009). Numerical modelling of exhaled droplet nuclei dispersion and mixing in indoor environments. Journal of Hazardous Materials, 167: 736–744.

    Article  Google Scholar 

  29. Münch W, Rüden H, Schkalle Y-D, Thiele F (1986). Flow of micro-organisms in a hospital stair-shaft. Full-scale measurements and mathematical model. Energy and Buildings, 9: 253–262.

    Article  Google Scholar 

  30. Patankar SV (1980). Numerical Heat Transfer and Fluid Flow. New York: Hemisphere Publishing Corporation.

    MATH  Google Scholar 

  31. Phillips DA, Sinclair RJ, Schuyler GD (2004). Isolation room ventilation. Design case studies. In: Proceedings of IAQ Conference, ASHRAE.

  32. Qian H, Li Y, Sun H, Nielsen PV, Huang X, Zheng X (2010). Particle removal efficiency of the portable HEPA air cleaner in simulated hospital ward. Building Simulation, 3: 215–224.

    Article  Google Scholar 

  33. Rygielski L, Uden D (2007). Creating comfort. Nine considerations for selecting the right hospital HVAC system. Health Facilities Management, 20(1): 19–23.

    Google Scholar 

  34. Solidworks (2009). http://www.solidworks.com.

  35. Soper M (2008). Pandemic ready. HVAC systems for worst-case scenarios. Health Facilities Management, 21(10): 49–52.

    Google Scholar 

  36. Stanley NJ, Kuehn TH, Kim SW, Raynor PC, Anantharaman S, Ramakrishnan MA, Goyal SM (2008). Background culturable bacteria aerosol in two large public buildings using HVAC filters as long term, passive, high-volume air samplers. Journal of Environmental Monitoring, 10: 474–481.

    Article  Google Scholar 

  37. Talon D, Schoenleber T, Bertrand X, Vichard P (2006). Performances of different types of airflow system in operating theatre. Annales de Chirurgie, 131: 316–321.

    Article  Google Scholar 

  38. Tang J, Li Y, Eames I, Chan P, Ridgway G (2006). Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises. Journal of Hospital Infection, 64: 100–114.

    Article  Google Scholar 

  39. Tellier R (2006). Review of aerosol transmission of influenza A virus. Emerging Infectious Diseases, 12: 1657–1662.

    Article  Google Scholar 

  40. Tunga YC, Hu SC, Tsaia TI, Changa IL (2009). An experimental study on ventilation efficiency of isolation room. Building and Environment, 44: 271–279.

    Article  Google Scholar 

  41. UNI 10339 (1995). Air-conditioning systems for thermal comfort in buildings. General, classification and requirements. Offer, order and supply specifications. Italian Standard.

  42. UNI EN 13779 (2005). Ventilation for non-residential buildings—Performance requirements for ventilation and room-conditioning systems. Italian Standard.

  43. van Schijndel AWM (2009). Integrated modelling of dynamic heat, air and moisture processes in buildings and systems using SimuLink and COMSOL. Building Simulation, 2: 143–155.

    Article  Google Scholar 

  44. VanSchiver M, Miller S, Hertzberg J (2009) Particle image velocimetry of human cough. Indoor Air, 19: 1–21.

    Article  Google Scholar 

  45. Verdier O (2004). Benchmark of Femlab, Fluent and Ansys. Lund University.

  46. Walker J, Hoffman P, Bennett A, Vos M, Thomas M, Tomlinson N (2007). Hospital and community acquired infection and the built environment—Design and testing of infection control rooms. Journal of Hospital Infection, 65: 43–49.

    Article  Google Scholar 

  47. Yu CP, Diu CK (1983). Total and regional deposition of inhaled aerosols in humans. Journal of Aerosol Science, 14: 599–609.

    Article  Google Scholar 

  48. Zhao B, Yang C, Chen C, Yang CFX, Sun L, Gong W, Yu L (2009). How many airborne particles emitted from a nurse will reach the breathing zone/body surface of the patient in ISO Class-5 single-bed hospital protective environments? A numerical analysis. Aerosol Science and Technology, 43: 990–1005.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Carla Balocco.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Balocco, C. Hospital ventilation simulation for the study of potential exposure to contaminants. Build. Simul. 4, 5–20 (2011). https://doi.org/10.1007/s12273-011-0019-6

Download citation

Keywords

  • CFD
  • transient simulation
  • ventilation
  • HVAC
  • VAV plant
  • virus diffusion
  • isolation rooms