The Potential optimum cooling effect of vegetation with ground surface physical properties modification in mitigating the urban heat island effect in malaysia

This study focuses on the optimum cooling effect of vegetation and ground surface albedo modification at street level in mitigating urban heat island (UHI) in Persiaran Perdana, Putrajaya and benefits towards outdoor human thermal comfort and building energy performances. The modification of vegetation and ground surface materials were focused on both physical properties - ie. tree canopy density and materials albedo values. Several methodologies phases through remote sensing satellite imagery, computer simulation, field measurement and surveys pro grammes were developed and conducted in order to achieve the aim and objectives of study. Particularly, ENVI-met surface-plant-air microclimate model was used to predict the impact of modification according to three proposed scenarios - i.e (i) LAD < 0.5, (i) LAD > 1.5; and (ili) LAD > 1.5 and albedo > 0.8. The model was success fully validated and reliable to present the actual urban microclimate condition of Persiaran Perdana through the correlation of measured and computed experiments. Four local species were measured and simulated based on variation in leaf area index (LAI) and leaf area density (LAD) to measure per-tree cooling effect performances and used as a reference in final simulation of proposed scenarios. The outcome was used in evaluating the impact of modification and used to assess later its benefits towards human thermal comfort and building energy performances. The outdoor thermal comfort was assessed based on site questionnaire and the outcome developed local physiological equivalent temperature (PET) as reference to evaluate modification benefits towards outdoor comfort level. Then, the building energy performances were evaluated using validated HTB2 model that based on site field measurement outcome and one selected building as a reference.