CIBSE Technical Symposium, London, UK 12-13 April 2018 Page 1 of 11 Simulation of urban solar reflections and their impact on building performance RUTH SHILSTON MENG (HONS), CENG, MIMECHE, RWDI, RUTH.SHILSTON@RWDI.COM RYAN DANKS BASC, PENG, RWDI, RYAN.DANKS@RWDI.COM Abstract Recent media attention has highlighted several cases where solar reflections from building facades caused serious impacts on their surroundings. Impacts ranged from general nuisance to property damage and human safety concerns. The trend in new construction of high window-to-wall ratios and increased use of reflective facade materials will likely increase the frequency and impact of urban solar reflections. This paper reviews several solar reflection case studies performed by the authors conducted using a custom simulation tool. The assessment of reflection severity (both in a pre-construction, predictive context and a post-construction forensic context) and mitigation effectiveness are all explored. Lessons learned during these studies will highlight to the building services community the influence of high performance façade selection (often chosen to reduce internal heat loads) on solar reflections in the urban environment. The paper specifically demonstrates the impact that reflected heat can have on neighbouring buildings. This paper also provides guidance about how to avoid features that lead to visual and thermal reflection issues and presents approaches that can be used to both quantify and mitigate issues at the design stage. Keywords solar, glare, reflected heat, glazing, simulation 1.0 Introduction Experiencing impacts from reflected sunlight is often unavoidable for urban inhabitants. The majority of the time such reflections are simply a nuisance, however in recent years, well publicized cases of reflections causing dangerous visual impairment (1), property damage (2) and personal injury (3) have led to architects and designers wanting a deeper understanding of how their building will reflect solar energy and how that light and heat will impact the surrounding environment. Over the past several years the authors have developed a custom simulation tool to better understand the impacts of solar reflections within complex urban environments (4). This tool has been used for numerous studies of the impacts of a proposed building’s reflections, as well as in forensic analyses, which have aimed to identify the sources of problematic reflections and evaluate the effectiveness of mitigation options. Field measurement programs have also been undertaken, with the aim of validating the simulation tool, as well as to provide context with respect to the intensities of existing reflections in a neighbourhood and how those compare to the predicted intensities of reflections from a proposed building. Due to the sensitive nature of the work performed, details which could identify the study buildings have been purposely omitted. Buildings shown in all figures have been modified to hide any unique features.