A comprehensive district scale simulation method to evaluate active and passive building strategies and their influence on outdoor thermal comfort in a hot and humid tropical climate

Abstract

Outdoor thermal comfort (OTC) is one of the key factors to define the city‘s livability, which is also known to have direct impacts on people‘s health and wellbeing. One of the biggest contributing factors to the increase in urban thermal discomfort is the anthropogenic heat emissions from buildings, which is worsened by the over-reliance trend on air-conditioner use in urban environments especially in the tropical region. To counteract this urban heating, extensive research had been done to make modern day buildings more climate responsive, which includes measures on active and passive design strategies. Given the complexity of both urban and climate systems, an integrated modelling approach of building energy and urban microclimate is needed to identify the optimal set of strategies. In this study, the interaction between the building energy balance and the atmospheric canopy layer is modelled using the urban microclimate model, PALM-4U coupled with the mesoscale climate model, WRF, for its boundary conditions, and the building energy model, City Energy Analyst (CEA). To represent the performance of various cooling systems, we modified the existing source code of PALM-4U, to integrate external heat profiles computed by CEA to PALM-4U, and to allow for customized anthropogenic heat (AH) rejection locations. In the end, we implement the proposed workflow to compare the influence of active strategies (i.e., AH released on wall surfaces as a baseline, central cooling systems with standard and high energy efficiency buildings, and district cooling) on the microclimate. The results suggest that the district cooling scenario performs the best in terms of microclimate and OTC for a high-density Central Business District (CBD) area. Minor discrepancies were found between the standard and high building efficiency.