Outdoor Thermal Comfort: Coupling Microclimatic Parameters with Subjective Thermal Assessment to Design Urban Performative Spaces

• Main Authors: Mohamed H. Elnabawi, Neveen Hamza
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Series: Buildings
• Subjects: outdoor thermal comfort; physiological equivalent temperature (PET); thermal sensation votes (TSV); computational fluid dynamics (CFD)
• Online Access: https://www.mdpi.com/2075-5309/10/12/238

Thermal comfort plays a main role in encouraging people to use outdoor spaces, specifically in hot arid and humid climates. The reconciliation of climatic aspects during the urban design phase is limited in implementation, due to the need for multidisciplinary collaboration between desperate scientific fields of climatology, urban planning, and urban environmental modelling. This paper aims to create an integrated interface between the microclimate, outdoor thermal comfort, and design guidelines. The investigation combines subjective and objective approaches, including on-site field measurements, a structured questionnaire using the seven-point American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE 55) thermal sensation votes, and a correlation study of these votes and the microclimatic parameters. Pedestrian thermal comfort was then examined under six shading scenarios, addressing the form and opening of shading devices using computational fluid dynamics. Modelling is based on four dependent variables: wind velocity, ventilation flow rate, air temperature, and the physiological equivalent temperature (PET) index. Findings indicate that the form and location of apertures of the shading devices were the dominant factors in achieving thermal comfort on the urban scale, and led to a reduction in air temperature and a physiological equivalent temperature of 2.3–2.4 °C. Subjective votes indicate that people who live in hot arid climates have a wider range of adaptation and tolerance to local climatic conditions Accordingly, a psychometric chart, for the case study outdoor thermal comfort was developed,