Assessing the Impact of Solar Photovoltaics and Air Conditioning Waste Heat on Urban Heat Island Effects

Abstract

This report is a product of the research project ‘Assessing the Impact of Solar PV and A/C Waste Heat on Urban Heat Island Effects’ along with an extension of the Microclimate and Urban Heat Island Mitigation Decision-Support Tool (UHI-DS Tool) (http://uhimitigationindex.be.unsw.edu.au/uhitool/login.html). Initiated by the Energy Efficiency Decision-Making Mode (EEDMN), this project addresses the urban policy and development assessment need for understanding the interrelationship of solar PV applications, A/C waste heat, urban and building typologies, and urban overheating effects. This report outlines the key findings of the project by highlighting a set of interrelated attributes and their impacts on the outdoor and indoor thermal environments, based on a literature review of existing research and a case study of Macarthur Heights greenfield development in Western Sydney. Project outcomes provide evidence to inform government policy and a holistic approach to assessing urban planning and development. Findings from this project show that solar PV (with current energy conversion efficiencies) and A/C waste heat can contribute to outdoor air temperature increases while UHI mitigation strategies such as cool roofs and a combination of these mitigation options contribute to the outdoor air temperature reductions at the city and precinct scale. The impacts are influenced by not only the solar PV energy conversion efficiency, but also urban and building typologies, and local microclimate characteristics. Solar PV helps reduce peak electricity demand, however, the solar PV electricity generation potential decreases during extreme heat events compared to typical summer days. Existing literature suggests that the future improvement of solar PV energy conversion efficiency could potentially lead to air temperature deceases due to the significant reduction of excess heat release to the surrounding environment. The improved solar PV electricity generation potential could also significantly reduce carbon emissions, thereby mitigating larger scale climate change challenges. Hence, recommendations for government intervention options need to carefully consider the specific local development context and microclimatic conditions when developing solar PV strategies and UHI mitigation options.