Impact of different roofing mitigation strategies on near-surface temperature and energy consumption over the Chicago metropolitan area during a heatwave event

Abstract

This study examined the impact of cool roofs, green roofs, and solar panel roofs on near-surface temperature and cooling energy demand through regional modeling in the Chicago metropolitan area (CMA). The new parameterization of green roofs and solar panel roofs based on model physics has recently been developed, updated, and coupled to a multilayer building energy model that is fully integrated with the Weather Research and Forecasting model. We evaluate the model performance against with observation measurements to show that our model is capable of being a suited tool to simulate the heatwave event. Next, we examine the impact by characterizing the near-surface air temperature and its diurnal cycle from experiments with and without the different rooftops. We also estimate the impact of the rooftop on the urban island intensity (UHII), surface heat flux, and the boundary layer. Finally, we measure the impact of the different rooftops on citywide air-conditioning consumption. Results show that the deployment of the cool roof can reduce the near-surface temperature most over urban areas, followed by green roof and solar panel roof. The cool roof experiment was the only one where the near-surface temperature trended down as the urban fraction increased, indicating the cool roof is the most effective mitigation strategy among these three rooftop options. For cooling energy consumption, it can be reduced by 16.6 %, 14.0 %, and 7.6 %, when cool roofs, green roofs, and solar panel roofs are deployed, respectively. Although solar panel roofs show the smallest reduction in energy consumption, if we assume that all electricity production can be applied to cooling demand, we can expect almost a savings of almost half (46.7 %) on cooling energy demand.

Keywords: Cooling energy demand; Heatwave; Rooftops; Urban climate modeling.