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Understanding and evaluating the implications of photovoltaic solar panels (PVSPs) deployment on urban settings, as well as the pessimistic effects of densely populated areas on PVSPs efficiency, is becoming incredibly valuable. Thus, the deployment of low-efficiency, low-cost, and widely available PVSPs may diminish total solar reflectance, raising the risks of PVSPs-based urban heating, particularly during the summertime heatwaves. This study employs and assesses physical parameterizations that account for the impact of PVSPs on Sydney's urban environment in the context of the mesoscale model weather research and forecasting (WRF). To account for the impacts of PVSPs, the parameterization presented in this paper assumes that PVSP arrays are parallel, detachable from roofs, and consist of a single layer. Results showed that increasing PVSPs can raise peak summer ambient temperatures by up to 1.4 °C and surface temperatures by up to 2.3°C at city-scale. Temperature variability was found between the city's eastern and western parts due to the presence of PVSPs. In addition, local warming effects of PVSP were observed at urban district-scale as well. The large-scale deployment of PVSPs at local district-scale of the Sydney during a typical hot day caused air temperature to rise by 1.5 °C during the daytime and decrease by 2.7 °C at nighttime. The patterns of the city's ambient temperature distribution were found to be strongly dependent on synoptic meteorological conditions and advection flow strength. The maximum increases in sensible heat flux and latent heat flux were 245.5 Wm−2 and 11.5 Wm−2, respectively. Wind speed may be raised by up to 1.2 ms−2 due to regional low effect over city domain. As a result, large-scale deployment of PVSPs promotes advective flow between the city and its environs. Modification of the PVSPs in Sydney results in an increase in planetary boundary layer (PBL) heights of up to 537.9 m above the city and may lower pollutant concentrations at ground level. The advent of sea breeze in the city's eastern parts, which reduces the temperature of the coastal zone, along with inland westerly winds, which heat the city's western zones, lessened the intensity of the urban heat island (UHI) phenomenon induced by PVSPs warming. The findings of this study can be used to help policymakers make informed decisions about the use of PVSPs systems. PVSPs with a high solar reflectance in wavelengths that do not convert solar energy to electricity can be considered as an alternative solution to reduce local warming in urban environments. [ABSTRACT FROM AUTHOR]

Over many decades, buildings have been recognised as a significant area contributing to the negative impacts on the environment over their lifecycle, accelerating climate change. In return, climate change also impacts on buildings with extreme heatwaves occurring more frequently and raising the earth's temperature. The operation phase is the most extended period over a building's lifespan. In this period, office buildings consume most energy and emit the highest amount of greenhouse gas pollution into the environment. Building upgrading to improve energy efficiency seems to be the best way to cut pollution as the existing building stock is massive. The paper presents an economic analysis of energy efficiency upgrade of buildings with a focus of office buildings. The paper identifies upgrading activities that are commonly undertaken to upgrade energy efficiency of office buildings and a case study of three office buildings in Sydney, Australia has been used to analyse the results. The upgrading activities can improve the energy performance of the case study buildings from 3 stars to 5 stars NABERS energy rating in compliance with the mandatory requirement in the Australian government's energy policy. With the potential increase in energy price, energy efficiency upgrading will become more affordable, but currently, most of them, except solar panels and motion sensors show a negative return and would not be undertaken if they did not also contribute to higher rental income and an increased life span of the building. The upgrading discussed in the paper represent a potentially attractive alternative to demolition and building anew. [ABSTRACT FROM AUTHOR]