The effect of different types of vegetation on thermal comfort in urban gorges in hot and dry climates
Subject Areas :
Architecture and urbanism
Tahereh koulivand
1
,
Nazanin Nasrollahi
2
1 - Academic faculty member, Department of Construction and Architecture, Technical and Vocational University, Tehran, Iran. *(Corresponding Author)
2 - Associate Professor, Architectural Engineering Department, Ilam University, Ilam, Iran.
Received: 2021-06-05
Accepted : 2021-09-08
Published : 2022-10-23
Keywords:
Vegetation,
Thermal Comfort,
urban gorges,
Envi-Met,
Isfahan,
Abstract :
Background and Objective: egetation is used in different forms in cities and in urban gorges and it helps to improve the temperature conditions of the environment by shading or evaporative cooling. Surveys conducted in the city of Isfahan show that grass, bushes and trees are the three most frequent forms in the gorges of this metropolis. The purpose of this research is to choose the best form of vegetation cover in Isfahan urban gorges according to the H/W ratio and different orientations.
Material and Methodology: Envi-met v4.1 software was used to check the effectiveness of vegetation in urban gorges. The conditions of urban gorges and frequent vegetation in the environment were determined by field investigation, then the best form of vegetation cover in the urban gorges of Isfahan was selected by computer simulation, and its density level and type were investigated in a number of urban gorges of Isfahan in the summer season.
Finding: The results obtained from the simulations revealed that the tree shows the most appropriate performance among the 5 proposed models and the tree in the ratio of height to width of 1 in all four orientations causes the greatest decrease in temperature in the summer season and in the ratio of height to width of 3 The best thermal conditions have been created.
Discussion & Conclusion: The results of the research indicate that among the different scenarios, the tree pattern alone has a greater cooling effect than the combined patterns with grass and short bushes. This pattern is the best in all the ratio of height to width and orientation.
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_||_
Bourbia, F. Awbi, H.B. Building cluster and shading in urban canyon, 2004, Renewable Energy, Vol. 29. - pp. 291-301.
health and Climate change health and Climate change [Online] // the lancet. - 2009. - http://www.thelancet.com/series/health-and-climate-change.
Bourbia, F. Boucheriba, F. Impact of street design on urban microclimate for semi arid climate (Constantine), 2010, Renewable Energy, Vol. 35.
Oke, R.T et al. Simulation of surface urban heat islands under ‘ideal’ conditions at night part 2: Diagnosis of causation, 1991, Boundary-Layer Meteorology, 4 : Vol. 56.
Ahmad, A. Khare, M and Chaudhry, K.K. Wind tunnel simulation studies on dispersion at urban street canyons and intersections—a review, 2005, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 93. pp. 697-717.
Oke, R.T. Street design and urban canopy layer climate, 1988, Energy and Buildings, 1-3 : Vol. 11.
Johansson, E. Influence of urban geometry on outdoor thermal comfort in a hot dry climate, 2006, BuildEnviron, Vol. 41.
Lin, t. Matzarakis, A. and Hwang, RL. Shading effect on long-term outdoor thermal comfort, 2010, Building and Environment, Vol. 45
Jamei, E et al. Review on the impact of urban geometry and pedestrian level greening on outdoor thermal comfort, 2016, Renewable and Sustainable Energy Reviews, Vol. 54. - pp. 102-117.
Matzarakis, A. Rutz, F. and Mayer, H. Modelling radiation fluxes in simple and complex environments—application of the RayMan model, 2007, Int J Biometeorol,. - Vol. 51.
Abreu-Harbich, L.V. Labaki, L.C and Matzarakis, A. Thermal bioclimate in idealized urban street canyons in Campinas, Brazil, 2012, International Conference on Urban Climates, Vol. 8.
Herrmann, J. Matzarakis, A. Mean radiant temperature in idealised urban canyons—examples from Freiburg, Germany, 2012, Int J Biometeorol, Vol. 56.
Nunez, M. Oke, R.T. Energy balance of an urban Canyon . 1997
Gill, SE. et al. Adapting Cities for Climate Change: The Role of the Green Infrastructure, 2007, Built Environment, Vol. 33. - pp. 115-133.
Givoni, B. Impact of planted areas on urban environmental quality: A review, 1991, Atmospheric Environment. Part B. Urban Atmosphere, 3 : Vol. 25.
Grimmond, C.S.B. Oke, T.R. An evapotranspiration-interception model for urban areas, 1991, Water Resour. Res., Vol. 27.
Bonan, G.B. Effects of land use on the climate of the united states, 1997, National Center for Atmospheric Research, Vol. 37. - pp. 449-486.
Byrne, L. Bruns, M. and Chung Kim, K. Ecosystem Properties of Urban Land Covers at the Above ground-Belowground Interface, 2008, Ecosystems, Vol. 11.
Fahmy, M. Sharples, S. and Yahiya, Y. LAI based trees selection for mid latitude urban developments: A microclimatic study in Cairo, Egypt, 2010, Building and Environment, Vol. 45. - pp. 345-357.
Oliveira, S. Andrade, H. Vaz, T. The cooling effect of green spaces as a contribution to the mitigation of urban heat: A case study in Lisbon, 2011, Lisbon : Building and Environment, Vol. 46.
Akbari, T. Urban climates and heat islands: albedo, evapotranspiration, and anthropogenic heat, 1997, Energy and Buildings, Vol. 25.
Georgi, JN. Dimitriou, D. The contribution of urban green spaces to the improvement of environment in cities: Case study of Chania, 2010, Greece, Vol. 45. - pp. 1401-1414.
Akbari, T et al. Peak power and cooling energy savings of shade trees, 1997, Energy and Buildings, Vol. 25. - pp. 139-48.
Ali-Toudert, F and Mayer H. Effects of asymmetry,galleries, overhanging façades and vegetation on thermal comfort in urban street canyons, 2007, SolEnergy, Vol. 81.
Hien Wong, N. Yu, C. Study of green areas and urban heat island in a tropical city, 2005, Habitat International, Vol. 29. - pp. 547-558.
Sawka M [et al.] Growing summer energy conservation through residential tree planting . Landscape and Urban Planning, 2013. - Vol. 113. - pp. 1-9.
Vailshery L, Jaganmohan M and Nagendra H Effect of street trees on microclimate and air pollution in a tropical city . Urban Forestry & Urban Greening, 2013. - Vol. 12. - pp. 408-415.
Srivanit M and Hokao K Evaluating the cooling effects of greening for improving the outdoor thermal environment at an institutional campus in the summer Building and Environment, 2013. - Vol. 66. - pp. 158-172.
R. OF IRAN METEOROLOGICAL ORGANIZATION. http://www.esfahanmet.ir/
Huttner, S. Bruse, M. Numerical modeling of the urban climate, a preview on Envi-met 4.0, The seventh International Conference on Urban Climate. - Yokohama,Japan : [s.n.], 2009.
A Optimizing the Effect of Vegetation for Pedestrian Thermal Comfort and Urban Heat Island Mitigation in a Hot Arid Urban Environment, 2014
Krüger, E. Pearlmutter, D. and Rasia, F. Evaluating the impact of canyon geometry and orientation on cooling loads in a high-mass building in a hot dry environment, 2010, Applied Energy, 6 : Vol. 87.
envi-met.com
Patz, J.A. Campbell-Lendrum, D. Patz, J.A., Campbell-Lendrum, D., Impact of regional climate change on human health, 2005, Nature, Vol. 438. - pp. 310–317.
Wania A [et al.] Analysing the influence of different street vegetation on traffic-induced particle dispersion using microscale simulations. Environmental Management, 2012. - Vol. 94.
Perini, K. Magliocco, A. Effects of vegetation, urban density, building height, and atmospheric conditions on local temperatures and thermal comfort, 2014, Urban Forestry & Urban Greening, 3 : Vol. 13.
Leuzinger, S. Vogtb, R. and Körner, CH. Tree surface temperature in an urban environment, 2010, Agricultural and Forest Meteorology, 1 : Vol. 150.
Shahidan M [et al.] A comparison of Mesua ferrea L. and Hura crepitans L. for shade creation and radiation modification in improving thermal comfort Landscape and Urban Planning, 2010. - 3 : Vol. 97. - pp. 168-181.
