Exploring the comprehensive optical-thermal performance:Experimentation of novel windows for building physics
[Objective]The indoor lighting environment and thermal conditions are closely related.Traditional university building-physics experiments typically involve separate optical and thermal assessments,resulting in a timing misalignment that impedes students'holistic understanding of indoor lighting and thermal environments.To overcome this challenge,a novel phase-change smart window is developed,and a comprehensive experimental framework for assessing light and thermal performance relevant to building physics is proposed.[Methods]The experiments primarily involve measuring and evaluating indoor thermal environment parameters using phase-change material(PCM)windows;assessing indoor optical parameters using micro-electro-mechanical(MEMS)system windows;and simultaneously measuring light and thermal environment parameters using phase-change smart windows,accompanied by analysis of their coupling relationship through comparative analysis of results.The experiments are divided into four groups conducted simultaneously,which involve the installation of double-glazed windows,PCM windows,MEMS windows,and the new type of phase-change smart windows.The experiment highlights the integration of indoor lighting and thermal environments by comparing temperature changes on the inner and outer surfaces of double-glazed and PCM windows.[Results]The results indicate that PCM reduces the peak temperature on the glass's inner surface but increases the warming rate and reduces the peak temperature on the outer surface but increases the temperature during the cooling phase.The thermal performance and heat transfer characteristics of PCM windows can be quantitatively analyzed.A comparison of the illuminance changes at points near and far from the window between double-glazed and MEMS windows confirms that MEMS reduces illuminance near the window while increasing it at points farther from the window,thus enhancing indoor illuminance uniformity.Additionally,the MEMS system's ability to reduce indoor glare,reduce the need for artificial lighting,and maximize the use of natural light is verified.A comparison of parameters between the new window group and the other three groups reveals that indoor heat gain is notably affected by solar radiation,emphasizing the crucial role of abundant natural lighting in creating a quality indoor light environment.During sunny summer days with ample indoor lighting,solar radiation increases indoor air temperature and mean radiant temperature,reducing thermal comfort.Conversely,inadequate natural lighting results in lower indoor temperatures but necessitates more artificial lighting,leading to a subpar light environment.Elevated indoor temperatures and illuminance levels require increased cooling energy consumption.The incorporation of the latest indoor light and thermal environment evaluation standards,such as CPMV for thermal environment assessment,which considers the influence of solar radiation on thermal comfort,and the inclusion of relative pupil size as a crucial indicator for assessing the light environment,provides a more objective reflection of indoor light comfort conditions.[Conclusions]By aligning with building energy-saving objectives,improving indoor light and thermal environments,enhancing students'comprehensive research capabilities,and deeply integrating fundamental building-physics knowledge into architectural design,this approach aims to enrich the educational experience.
building physicsoptical-thermal performancenovel windowscomprehensive experimental
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