A Strategic Planning Framework for Outdoor Thermal Comfort in Urban Head Island


Joint Research Collaboration
Sponsor REPA – Research and Education Promotion Association
Address 9F, Ryu Bo Building, 1 Chome-1-1 Kumoji, Naha City, Okinawa 900-0015, Japan
Grant Number P02EN2201JP02
Grant Year 2022
Principal Investigator (PI) Will be appointed later by the Academic Affairs Department.
Principal Researcher (PR) Mr. Vaibhav Rai Khare
Research Outcome In progress
Contact editorial@repa.jp
Vaibhav is a post graduate in Energy Engineering and has 9 years of experience in the field of Sustainability, Energy Efficiency, Energy & CFD simulation and Energy Policy Advocacy. He has more than 15 research papers published in various journals and international conferences. He is a founder member of IBPSA-India chapter.
A Strategic Planning Framework for Outdoor Thermal Comfort in Urban Head Island
Purpose and Objective Global climate change and rapid urbanization are deteriorating the livability status of the world’s population. It is well known that improving the quality of life in urban areas requires efficient buildings and urban public spaces with better thermal comfort. Increasing air temperature in urban areas due to urban heat island (UHI) has been a problem of global concern since industrialization. This phenomenon of UHI is attributed to physical changes in the urban environment and increased dependence on mechanically driven systems, increasing energy end-use. The declining outdoor thermal comfort levels are one of the direct impacts of the UHI phenomenon that should be of public concern.
Significance Due to rapid urbanization in cities, the characteristics of outdoor urban microclimates have been influenced by altering pedestrians’ perception and increasing the urban heat island effect. This poses challenges to many researchers and urban space designers in finding appropriate methods to reduce the urban heat island and thus to enhance the thermal comfort level of outdoor spaces to prolong the period of their use of space and viability as urban retreats. However, there is limited research conducted on outdoor thermal spaces. Micro-climate conditions in urban open spaces are directly linked to the configuration of the building. There are different indices developed to represent thermal comfort based on several parameters. This study aims to develop an outdoor human thermal comfort index that is physiologically valid across a wide range of environmental conditions. The influence of urban geometry on the micro-climate and human comfort in urban spaces is a very important aspect to consider when estimating outdoor comfort.
Problem and Methodology The purpose of this study is to review the outdoor thermal comfort factors based on the UHI mitigation strategies, which include cool roof non-roof (shading with structure tree plantation water bodies) and covered parking. A 3D reference model of a city has been developed in the ‘Grasshopper’ simulation tool. The outdoor thermal comfort indices (OTCI) have been evaluated for all the strategies individually and combined as well. The study also expects to highlight the CFD simulation as a tool in the field of urban design.
Conclusion The proposed methodology makes use of simulation tool Grasshopper, providing a comprehensive result to find their effect on the micro-climate and outdoor thermal comfort. Based on the simulation results the most important design factor has been identified in urban geometry to reduce the UHI effect. The Outdoor Thermal Comfort Indices (OTCI) have been calculated for the UHI mitigation strategies individually and combined. This study gives an idea to the urban designers and planners about how to enhance outdoor thermal comfort by reducing the UHI. This study also emphasizes the importance of the use of outdoor spaces. CFD simulation tool can be a meaningful tool to simulate the intangible microclimate parameters and predict the outdoor thermal comfort with the human thermal comfort index.
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