Modeling the effects of future urban planning scenarios on the Urban Heat Island in a complex region

Abstract

Because of the global warming, urban planning strategies must be investigated to reduce the building energy consumption and increase the thermal comfort in cities. In the framework of Energy Strategy 2050 of Switzerland, this research aim to highlight the impact of future climate change on urban planning and proposes strategies to help urban planners and policymakers face this new challenge particularly in a future where heat waves are going to become common at mid-latitudes. However, to do so in the best possible way, the models currently used have to be robust enough in complex regions (with lakes and mountains) to evaluate future planning scenarios. First, this study proposes a methodology to cluster buildings in urban areas and use it in a mesoscale numerical weather prediction system to evaluate the urban heat island and its impact on the energy demand for cooling at the city scale. Second, this research proposes urban planning strategies to reduce building energy consumption due to the urban heat island phenomenon in the city of Lausanne.The model has been validated with six different weather stations. It emphasizes the presence of the urban heat island in the Lemanic region which lead to the increase of air temperatures in Geneva and Lausanne by 2°C during the day and by up 4°C during the night compared to the surrounding areas. The presence of multiple cities around the lake lead to the creation of the urban heat archipelago. We demonstrate with these simulations that the performance of the WRF model is very heterogeneous in this complex setting. In the evaluation of the future urban densification scenario, we noted that there will be an increase in temperature caused by the UHI phenomenon by up 0.6°C. The increase of albedo of roofs and walls and the use of greenings are good mitigation solutions, with a most significant impact for the albedo. In addition to the climatic impact, the model highlights that the densification scenario has a significant impact on the peak cooling demand.

A review of assessment methods for the urban environment and its energy sustainability to guarantee climate adaptation of future cities

“…Contrary to UWG and CAT, CIM also computes the horizontal wind speed and has recently been extended and integrated into the Weather Research and Forecast model [126] to include advection processes [39]. It was shown here that there was a significant improvement to the computation of high-resolution vertical profiles which can play a significant role in the computation of the building energy demand at the urban scale [127] and the outdoor thermal comfort [128].…”

Conceptualizing Spatial Heterogeneity of Urban Composition Impacts onPrecipitation Within Tropics

“…(Abd El-Hamid, 2020;Bherwani, Singh, & Kumar, 2020;Patra, Sahoo, Mishra, & Mahapatra, 2018;Sun, Gao, Li, Wang, & Liu, 2019) Intensive urban growth is believed to have disrupted the hydrological cycle, contributing to the increase in UHI, thus intensifying the magnitude of precipitation. It is interconnected in such a way that changes and increase in land-use area alters the annual temperatures that cause the alteration of precipitation patterns (Abd El-Hamid, 2020;Bherwani et al, 2020;Labedens, Scartezzini, & Mauree, 2018;Paul et al, 2018;M. Ren, Xu, Pang, Liu, & Du, 2020).…”

“…However, urban heterogeneities and the impact of urban morphology cannot be represented by simple surface parameterization as it does not represent horizontal and vertical surfaces. Therefore, established methods in defining the reclassification of land use will be adapted accordingly (Labedens et al, 2018;Sharma et al, 2017;Xu, 2019).…”

Developing an Integrative Theoretical Framework for Climate Proofing Spatial Planning Across Sectors, Policy Levels and Planning Areas

“…These changes give rise to different thematic challenges which depend on geographical location, topographical and climatic conditions, as well as other influencing factors such as land use. While, in coastal areas, for example, protection against storm surges is the main concern [1][2][3], other areas primarily suffer from heatwaves and droughts, causing forest fires and/or water scarcity [4][5][6]. Alpine areas, on the other hand, have specific challenges primarily related to gravitational events such as erosion, landslide and rockfall.…”