African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1014

Article in Press

Evaluation of outdoor human thermal comfort conditions in selected streets of Nairobi City's Centre

Emmanuel Ochola Matsaba, Ines Langer, Aggrey Ochieng Adimo, John Bosco Mukundi and John Mwibanda Wesonga

  •  Received: 11 March 2020
  •  Accepted: 09 October 2020
This paper evaluated the outdoor human thermal comfort conditions for urban heat island management in Nairobi city. Environmental parameters were measured at microclimatic and instantaneous scales on a typical summer day in Nairobi City's Centre's selected streets. The RayMan software package and ENVI-met v4.0 BETA model were used to evaluate both measured and simulated physiologically equivalent temperature (PET) to determine possible urban heat stress and thermal comfort. The results indicated temporal heterogeneity in PET, urban heat stress, and human thermal comfort in all the six streets, which could be attributed to heterogeneous micrometeorological street conditions due to variability in the urban parameters (street form and structure) of Nairobi city. Daytime recorded strong heat stress during nighttime recorded moderate cool stress. The relationship between PET conditions and the controlling microclimatic parameters (air temperature, relative humidity, wind speed, and radiant temperature) revealed a significant regression with a variance (R2) of 0.61, 0.85, 0.41, and 0.85, respectively. Therefore, the implications of urbanization on the planning of urban heat management and services should be area-specific streets and city parameters. Further analysis to establish both spatial and temporal thermal comfort of the city in the future is recommended.

Keywords: Heat stress; Physiologically Equivalent Temperature (PET); Thermal Comfort; Measurements; Micrometeorology; Simulations