Cooling Effect of Shaded Open Spaces on Long-term Outdoor Comfort by Evaluation of UTCI Index in two Universities of Tehran.

Document Type: Original Article


1 M.Arch., Department of Architecture, Qazvin Branch, Islamic Azad University, Qazvin, Iran.

2 Assistant professor of Landscape Architecture, Faculty of Architecture and Urban studies, University of Science and technology, Tehran, Iran


Environmental matters are more complicated. Sustainability of environment requires an integrated approach to decisions making, planning, and management. Therefore, there is a need for a professional and systematic environmental management approach to reducing the consumption of resources. This approach is generally lacking in most universities, and therefore achievement of sustainability becomes much more difficult. This paper focuses on the comparative study of the effects of the sky view factor (SVF) on mean radiant temperature (Tmrt) and the thermal indices derived from these parameters in two different universities in Tehran: IUST and University of Amir-Kabir. The outdoor thermal conditions of these campuses because of different levels of greenery in spring and summer create different conditions in terms of thermal comfort or thermal stress. In this paper, environmental data by the experimental approach(field measurment) and they were analyzed by statical manner. The authors calculated UTCI by the UTCI calculator as thermal stress in the spring and summer of 2015. Subsequently, by decreasing the sky view factor by a value of 0.4 (increasing the shaded spaces), the mean radiant temperature will decrease by 3.04°C. These changes of Tmrt effect on the reduction of UTCI values. Comparison of UTCI index in two campuses illustrate that on average, there is a 1.28°C difference on the UTCI index and in September the IUST campus is 2.72°C cooler on the UTCI scale. The results of this study give correct guidelines to designers to create much more shaded open spaces to reach sustainable environment in universities.


  1. Ahmed M. & Abdel-Ghany & Ibrahim M. & AL-Helal & Mohamed R. Shady. (2014) , ‘Evaluation of human thermal comfort and heat stress in an outdoor urban setting in summer under arid climate condition’. Environment Protection Engineering. 40(3).
  2. Ahmed, K. S. (2003). Comfort in urban spaces: defining the boundaries of outdoor thermal comfort for the tropical urban environments. Energy and Buildings, 35(1), 103-110.
  3. Ali-Toudert F, Mayer H. (2006), a ‘Numerical study on the effects of aspect ratio and orientation of an urban street canyon on outdoor thermal comfort in hot and dry climate’, Build Environ 41:94–108.
  4. Ali-Toudert, F., & Mayer, H. (2006). Numerical study on the effects of aspect ratio and orientation of an urban street canyon on outdoor thermal comfort in hot and dry climate. Building and environment, 41(2), 94-108.
  5. Andrade H, Alcoforado M- J. (2007), a ‘Microclimatic variation of thermal comfort in a district of Lisbon (Telheiras) at night. Theoretical and Applied Climatology; 92:225–37.
  6. Behzadfaz, M., & Monam, A. The impact of sky view factor on outdoor thermal comfort; case study: Tehran urban parks.(2012).‏ Journal of ARMANSHAHR,   FALL of  2010-WINTER 2012, Volume 3 , Number 5; Page(s) 23 To 34.(In Persian)
  7. Benzinger, T.H.(1979).The physiological basis for thermal comfort , Indoor climate. Danish building research institute, Copenhagen.Pp.441-476.
  8. Bourbia, F., & Awbi, H. B. (2004). Building cluster and shading in urban canyon for hot dry climate: Part 1: Air and surface temperature measurements. Renewable energy, 29(2), 249-262.
  9. Brode.B & Kruger.E.L & Fiala.D. (2013),‘UTCI: Validation and practical application to the assessment of urban outdoor thermal comfort’, Institute of geography and spatial organization polish academy of science .86(1):11-20.
  10. Cheung, H. K. W., Coles, D., & Levermore, G. J. (2016). Urban heat island analysis of Greater Manchester, UK using sky view factor analysis. Building Services Engineering Research and Technology, 37(1), 5-17.
  11. Chung M.H. &Rhee E.K. (2014),‘Potential opportunities for energy conservation in existing buildings on a university campus: A field survey in Korea’, Energy and Building, 78176-182.
  12. Das, D. (2008). Urban Quality of Life: A Case Study of Guwahati, Springer Science+Business Media B.V., Soc Indic Res 88:297–310.
  13. Eliasson, I. (1996). Urban nocturnal temperatures, street geometry and land use. Atmospheric Environment, 30(3), 379-392.
  14. Eliasson, I., & Holmer, B. (1990). Urban heat island circulation in Göteborg, Sweden. Theoretical and Applied Climatology, 42(3), 187-196.
  15. Emmanuel R, Johansson E. (2006),‘Influence of urban morphology and sea breeze on hot humid microclimate: the case of Colombo’, Sri Lanka. Climate Research; 30:189e200.
  16. Faizi. M,  Monam. A, Ghazizadeh S.N (2015).Evaluation of users acoustic comfort in urban parks case study: Tehran urban parks.  Journal of environmental science and technology; Page(s) 437 To 448 .(In Persian)
  17. Geng Y, Liu K, Xue B, Fujita T. (2013),‘Creating a “green university” in China: a case of Shenyang University’,Journal of Cleaner Production. VOL (61).Pp13-19.
  18. Ghazizadeh, S. N., Monam, A., & Mahmoodi, A. S. (2010). The impact of the architectural design on the thermal comfort of the outdoor spaces in residential complexes. Honar–ha–ye–Ziba, 42, 59-70.(In Persian)
  19. Givoni B. (1998). Climate considerations in building and urban design. Wiley.
  20. Givoni, B. (1998). Climate considerations in building and urban design. John Wiley & Sons.
  21. Gulyas A, Unger J, Matzarakis A. (2006),‘Assessment of the microclimatic and human comfort conditions in a complex urban environment: modeling and measurements’, Building and Environment; 41:1713–22.
  22. H.M. Alshuwaikhat, I. Abubakar. (2008),‘An integrated approach to achieving campus sustainability: assessment of the current campus environmental management practices’,Journal of Cleaner Production 16 (16) 1777–1785.
  23. Hamada S, Ohta T. (2010),‘Seasonal variations in the cooling effect of urban green area on surrounding urban areas’,Urban Forestry & Urban Greening; 9: 15e24.
  24. He, X., Miao, S., Shen, S., Li, J., Zhang, B., Zhang, Z., & Chen, X. (2015). Influence of sky view factor on outdoor thermal environment and physiological equivalent temperature. International journal of biometeorology, 59(3), 285-297.
  25. Heidari.SH, Monam.A.(2013).Evaluation of thermal indices in outdoor thermal comfort’,Journal of geography and regional development.NO.20 .197-612 .(In Persian)
  26. Heidari.SH. (2009),‘Thermal comfort Temperature of Tehran’, a journal of the fine art of Tehran university.38:5-14.(In Persian)
  27. Heijs, W. (1994). The dependent variable in thermal comfort research: some psychological considerations, Thermal Comfort: Past, Present and Future. Proceedings of a conference held at the Building Research Establishment, Garston, 9-10 June 1993, pp. 40-51.
  28. Hensen, J. L. M. (1990).Literature review on thermal comfort in transient conditions, Building and Environment. 25 no. 4, pp. 309 - 316.
  29. Höppe P. (2002),‘Different aspects of assessing indoor and outdoor thermal comfort’, Energy Build.34:661e5.
  30. ISO. (1984),‘Moderate thermal environments determination of the PMV and PPD indices and Specification of the conditions for thermal comfort’,International Standard ISO 7730, International Organization for Standardization.
  31. Jendritzky. G & Havenith. G & Weihs. P & Batchvarova. E & Dedear. R (2007),‘The Universal Thermal Climate Index UTCI Goal and state of COST Action 730’,International Scientific Conference of BIOCLIMATOLOGY AND NATURAL HAZARDS. Poľana and Detvou, Slovakia, September 17 – 20.
  32. Johansson E. (2006),‘Influence of urban geometry on outdoor thermal comfort in a hot dry climate: A study in Fez, Morocco’,Building and Environment.41.1326–1338.
  33. Johansson E. (2006). Influence of urban geometry on outdoor thermal comfort in a hot dry climate: A study in Fez, Morocco. Building and Environment.41.1326–1338.
  34. Johnson, D. B. (1985). Urban modification of diurnal temperature cycles in Birmingham, UK. Journal of climatology, 5(2), 221-225.
  35. Kevin Ka-Lun Lau & Fredrik Lindberg & David Rayner & Sofia Thorsson. (2014),the effect of urban geometry on mean radiant temperature under future climate change: a study of three European cities’,Int Biometeorol.
  36. Lafortezza, R., Carrus, G., Sanesi, G., & Davies, C. (2009),‘Benefits and well-being perceived by people visiting green spaces in periods of heat stress’,Urban Forestry & Urban Greening, 8(2), 97-108.
  37. Limb,M(1992).Technical notes-an infiltration and ventilation glossary Air infiltration and ventilation center. p 36.
  38. Lin TP, Matzarakis A, Huang JJ. (2006),‘Thermal comfort and passive design of bus shelters’, In: Proceedings of 23rd conference on passive and low energy architecture, Geneva.
  39. Lin T-P, Matzarakis A, Hwang R-L. (2010),‘Shading effect on long-term outdoor thermal comfort’, Building and Environment; 45:213e21.
  40. Lindberg F, Grimmond CSB.(2011),‘Nature of vegetation and building morphology characteristics across a city: influence on shadow patterns and mean radiant temperatures in London’,Urban Ecosyst 14:617–634.
  41. Lindberg F, Holmer B, Thorsson S, Rayner D. (2013),‘Characteristics of the mean radiant temperature in high latitude cities - implications for sensitive climate planning applications’,Int J Biometeorol. Doi: 10. 1007/s00484-013-0638-y.
  42. Masmoudi S, Mazouz S. (2004),‘Relation of geometry, vegetation and thermal comfort around buildings in urban settings, the case of hot arid regions’,Energy Buildings 36(7):710–719.
  43. Matzarakis A, Rutz F, Mayer H. (2007),‘ Modelling radiation fluxes in simple and complex environments—application of the RayMan model’,Int J Biometeorol 51:323–334.
  44. Matzarakis, A., H. Mayer, M. G. Iziomon. (1999),‘Applications of a universal thermal index: physiological equivalent temperature’,Int. J. Biometeorol. 43, 76-84.
  45. McIntyre.D.A. (1980). Indoor climate. Applied science publishers, London, p 56.
  46. Monam, A. (2011),‘Comfortability in urban open spaces; evaluation of outdoor thermal comfort in urban parks’,(Ph.D.), Iran University of science and technology, Tehran.(In Persian)
  47. Monteiro A, Carvalho V, Sousa C. (2012),‘Excess mortality and morbidity during July 2006 heat wave in Porto, Portugal - Tmrt efficiency to anticipate negative effects on health. Proceedings of the 8th international conference on urban climates’,Dublin, Ireland, 6–10 August 2012.
  48. Motamedzade, M., and M.R. Azari. (2006),‘Heat Stress Evaluation Using Environmental and Biological Monitoring’,Pakistan Journal of Biological Sciences, 9(3), 457-59.
  49. Ng E, Chen L, Wang Y, Yuan C. (2012),‘A study on the cooling effects of greening in a high-density city: an experience from Hong Kong’,Building and Environment; 47:256e71.
  50. Niachou, K., Hassid, S., Santamouris, M., & Livada, I. (2008). Experimental performance investigation of natural, mechanical and hybrid ventilation in urban environment. Building and Environment, 43(8), 1373-1382.
  51. Nichol J, Wong MS. (2005),‘Modelling urban environmental quality in a tropical city’,Landscape and Urban Planning; 75:49–58.
  52. Nikolopoulou.M, Steemers.K.(2003),‘Thermal comfort and psychological adaptation as a guide for designing urban spaces’,Energy and Buildings.35.95-101.
  53. Norton B.A., Coutts A.M., Livesley S.J., Harris R.J., Hunter A.M., Williams N.S.G. (2013),‘Evaluating the cooling effects of greening for improving the outdoor thermal environment at an institutional campus in the summer’,Building and Environment, 66,158-172.
  54. Oke TR.( 1987). Boundary layer climates. United Kingdom: Psychology Press;.
  55. Olgyay,V.(1963).Design with climate. Princeton university press, Princeton, New Jersey.
  56. Oliveira S, Andrade H, Vaz T.( 2011),‘The cooling effect of green spaces as a contribute to the mitigation of urban heat: a case study in Lisbon’,Build and Environment; 46:2186e94
  57. Oliveira S, Andrade H. (2007),‘An initial assessment of the bioclimatic comfort in an outdoor public space in Lisbon’,International Journal of Biometeorology; 52:69–84.
  58. Papanastasiou DK, Melas D, Bartzanas T, Kittas C. (2010),‘Temperature, comfort and pollution levels during heat waves and the role of sea breeze’,Int J Biometeorol 54:307–317.
  59. Prata-Shimomura A.R. & Monteiro L.M. & Frota A.B. (2009),‘Physiological equivalent temperature index applied to wind tunnel erosion technique pictures for the assessment of pedestrian’,The seventh International Conference on Urban Climate. 29 June - 3 July 2009, Yokohama, Japan.
  60. Psikuta A. & Fiala D. & Laschewski G. & Jendritzky G. & Richard M. & Blazejczyk K. & Mekjavic L. & Rintamaki H. Dedear R. & Havenith G.(2012),‘Validation of the Fiala multi-node thermophysiological model for UTCI application’,Int J Biometeorol.56:443-460.
  61. Rzepa, M. (2009, June). The map of sky view factor in the center of Lodz. In 7th International Conference on Urban Climate.
  62. Shahidan MF, Jones PJ, Gwilliam J, Salleh E.( 2012),‘An evaluation of outdoor and building environment cooling achieved through combination modification of trees with ground materials’,Build and Environment; 58:245e57.
  63. Shashua-Ba.L, Hoffman M.E.(2003),‘Geometry and orientation aspects in passive cooling of canyon streets with trees’,Energy and Building.35.61-68.
  64. Spagnolo J, de Dear RJ. (2003),‘A field study of thermal comfort in outdoor and semi-outdoor environments in subtropical Sydney, Australia’,Building and Environment; 38:721–38.
  65. Srivanit M, Hokao K.(2013),‘Evaluating the cooling effects of greening for improving the outdoor thermal environment at an institutional campus in the summer’,Building and Environment.66158-172.
  66. Svensson, M. K. (2004). Sky view factor analysis–implications for urban air temperature differences. Meteorological applications, 11(03), 201-211.
  67. Svensson, M. K. (2004). Sky view factor analysis–implications for urban air temperature differences. Meteorological applications, 11(03), 201-211.
  68. Taleghani, M., Kleerekoper, L., Tenpierik, M., & van den Dobbelsteen, A. (2015). Outdoor thermal comfort within five different urban forms in the Netherlands. Building and environment, 83, 65-78.
  69. Thorsson S, Honjo T, Lindberg F, Eliasson I, Lim EM. (2007),‘Thermal comfort and outdoor activity in Japanese urban public places’,Environment and Behavior. 39:660–84.
  70. Thorsson S, Rocklöv J, Konarska J, Lindberg F, Holmer B, Dousset B, Rayner D. (2014),‘Mean radiant temperature – a predictor of heat-related mortality’,Urban Clim. Doi: 10.1016/j. uclim.2014.01.004.
  71. Unger, J. (2004). Intra-urban relationship between surface geometry and urban heat island: review and new approach. Climate research, 27, 253-264.
  72. Upmanis, H., & Chen, D. (1999). Influence of geographical factors and meteorological variables on nocturnal urban-park temperature differences--a case study of summer 1995 in Göteborg, Sweden. Climate Research, 13(2), 125-139.
  73. Wong NH, Jusuf SK, Win AL, Thu HK, Negara TS, Xuchao W. (2007),‘Environmental study of the impact of greenery in an institutional campus in the tropics’,Building and Environment; 42:2949e70.
  74. Wong NH, Jusuf SK. (2008),‘GIS-based greenery evaluation on campus master plan’,Landscape and Urban Planning; 84:166e82.
  75. Yamashita, S., Sekine, K., Shoda, M., Yamashita, K., & Hara, Y. (1986). On relationships between heat island and sky view factor in the cities of Tama River basin, Japan. Atmospheric Environment (1967), 20(4), 681-686.
  76. Yamashita, S., Sekine, K., Shoda, M., Yamashita, K., & Hara, Y. (1986). On relationships between heat island and sky view factor in the cities of Tama River basin, Japan. Atmospheric Environment (1967), 20(4), 681-686.
  77. Yan, H., Fan, S., Guo, C., Wu, F., Zhang, N., & Dong, L. (2014). Assessing the effects of landscape design parameters on intra-urban air temperature variability: the case of Beijing, China. Building and environment, 76, 44-53.
  78. Yuan, C., & Chen, L. (2011). Mitigating urban heat island effects in high-density cities based on sky view factor and urban morphological understanding: a study of Hong Kong. Architectural Science Review, 54(4), 305-315.
Website  references

  1. Google image of IUST. (2015). Retrieved from . At October.2015.
  2. Wikimapia image of the University of Amir-Kabir. (2015), Retrieved from of amir-kabir. At October.2015.