Evaluation of urban heat island for puebla City, Mexico

Abstract

A study for urban heat island (UHI) detection was focused on the historic center of Puebla City, México. For this study, a polygon was chosen, accounting for 45 points covering the main area where most historic buildings from the XVI century are located, plus high rates of traffic vehicle circulation takes place. After that, there are formulated routes to collect data in order to cover all points during three hours. The evaluation of UHI occurrence was done based on both environmental and landscape parameters, registering values for relative humidity (RH, %), light intensity (I, lux), temperature (T, °C), noise (decibels, dB), vegetation, pavement materials, height and main use of buildings, presence of water bodies and vehicle traffic flow rate. Data collection was done in two weather conditions: summer (warm and wet season) and fall (dry and windy season); at three hourly ranges: morning (6–9), afternoon (12–15) and evening (18–21). For data analysis a “traffic light” was formulated, with green being good, yellow being concern and red being critical. For this step the difference between maximum and minimum values was divided in three groups, plus an annular presentation (from center to outside morning, afternoon, night) allowed to make evident how the parameters evolved during the day. Results from temperature allowed to classify 6 sites as probable UHIs, a conclusion which is reinforced by the lack of vegetation, pavement material, building usage and amount of vehicles passing by. Another critical parameter is noise, since almost 50% of the sites have values above the recommended for healthy environments (<60dB) in the morning, and 11% of the sites are unacceptable at all times.