Temperature Cooling and Warming Rates in Three Different Built Environments within Nairobi City, Kenya

Urban canyon, urban park, and suburban surface air temperature data for hot-wet, hot-dry, cool-dry, and warm-wet periods in Nairobi city were analyzed to detect differences in the cooling and warming rates. Measurement of temperature for thirty continuous days was done at each of the three sites for each of the above periods. The cooling and warming rates were computed on an hourly basis beginning at 6.00 P.M., the approximate time of sunset. The results of the study showed that the largest cooling and warming rates were generally experienced during the hot-dry period while the lowest during the cool-dry period. Cooling and warming rates were also found to be the highest at the suburban site and the lowest at the urban canyon site. The differences in the conditions of the built environment at the three sites could explain the cause of the differential cooling and warming rates. The study recommends proper planning of the built environment to ameliorate the problem of excessive nocturnal heat loads within the built environment