Abstract
The Urban Heat Island (UHI) effect is a phenomenon whereby urban areas become warmer than their surrounding rural areas, due to the replacement of vegetation and soil with surfaces such as asphalt and concrete. The asphalt pavement surfaces tend to absorb a large amount of heat through solar radiation and increase the air temperature, which affects the operation of building heating and cooling systems, causing environmental problems and thermal discomfort. However, this energy can be collected by water circulated through buried copper pipes to cool down temperatures and be stored for other usages. This work aims to develop a method for determining the optimum areas to locate pavement solar collector (PSC) systems and simulate the reduction of ambient air and surface temperature by using a coupled computational modelling approach. Discrete ordinate model and solar-ray tracing were utilised for solar radiation effect modelling in the 3D simulation. Furthermore, the PSC prototype was developed, and lab-scale experiments were carried out for validation. Based on the simulated conditions, in the unshaded area, the asphalt slab’s near-surface temperature was reduced by up to 10℃ and the outlet water temperature increased by about 5℃. At the pedestrian height level, the air temperature was reduced up to 4.6℃. This study further expands the investigation of the variation of outdoor conditions such as air temperature and solar radiation. The results showed that the proposed method could be used to optimise the pavement solar collector’s positioning to reduce urban surface and air temperature.
Highlights
Urban heat island (UHI) phenomenon is caused by urban overheating, which is becoming a severe problem for many major cities in the world (Santamouris, 2020)
This research investigated the impact of the pavement solar collector (PSC) system on the urban street canyon thermal environment, including building surface temperatures, pavement temperature and cooling effect provided by water pipes
A coupled approach was developed to combine both the urban street canyon domain and the PSC domain, which allows analysing the impact of PSC on the urban street canyon temperature directly
Summary
Urban heat island (UHI) phenomenon is caused by urban overheating, which is becoming a severe problem for many major cities in the world (Santamouris, 2020). The solar energy absorbed by artificial surfaces such as building and ground surfaces, the heat is emitted from the surfaces to the urban environment. The microclimate of urban areas is more complex and usually has higher temperatures than rural areas due to the UHI phenomenon. The increased ambient temperature may cause thermal discomfort; high discomfort can lead to high energy and cost utilisation, further worsening the issue (Lin et al, 2020). A case study in Rome, Italy showed that the building cooling energy demand increased by 30% because of the UHI phenomenon, and the heating energy demand decreased by 11% (Guattari et al, 2018). High wind velocity could increase the atmospheric flowing, which reduces the temperature difference between urban and rural areas
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