A Parametric Optimization Approach to Mitigating the Urban Heat Island Effect A Case Study in Ancona, Italy
CHALLENGE - The aim of this paper is to identify a parametrization method that considers existing connections and relationships between traditional indicators of environmental sustainability as a step in combating climate change via urban strategies. A Mediterranean city (Ancona, Italy) is investigated with a multi-objective optimization platform modeFRONTIER, which uses Pareto optimality with the goal of mitigating the UHI (urban heat island).
SOLUTION - In this multi-objective optimization method, to determine thermal comfort, the predicted mean vote PMV was used, an index predicting the mean value of the subjective ratings of a large group of people on a seven-point thermal-sensation scale. The predicted percent dissatisfied (PPD) is a related index that predicts the percentage of a large group of people likely to feel thermally uncomfortable. The objective is to minimize urban compacity and energy consumption in order to limit heat exchange, and minimize the PPD index in order to achieve good outdoor thermal comfort. Guided by optimizer modeFRONTIER, the optimization process determines the climatic and spatial conditions that guarantee optimization of PMV and identifies the related PPD.
BENEFITS - Using NSGA-II in modeFRONTIER, results show not a single solution but rather a set of solutions that dominate the other possible solutions.Thermodynamic indicators (N1, N2, and N3) were considered in the study and the results show that compacity N1 and thermodynamic indicator N2 can be useful parameters when designing comfortable cities to improve thermal comfort, such as wide streets and medium-height buildings in places with low wind speed. Parameter N3 shows that, within the limits of the model, it is challenging to find optimal solutions when dealing with the city as a whole.