Effect of roof solar reflectance on the building heat gain in a hot climate
Effect of roof solar reflectance on the building heat gain in a hot climate
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DOI：
10.1016/j.enbuild.2008.06.015
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发表时间：
2008-01-01
影响因子：
6.7
通讯作者：
Selby, Neville
中科院分区：
文献类型：
--
作者：
Suehrcke, Harry;Peterson, Eric L.;Selby, Neville
屋面太阳反射率对建筑热工性能的影响往往被忽略。然而，浅色和深色屋顶表面的热增益有显着差异。本文导出了一个日照屋面平均日向下热流的计算公式。使用建筑物模拟，它首先表明，屋顶的热质量并不显着影响整体每日得热（虽然它会导致一个时间滞后和减少峰值热流）。因此，每天从屋顶获得的热量可以通过对一天中的稳态向下热传递的方程进行积分来估计。对于澳大利亚北部，推导出的方程表明，浅色屋顶的总热量（空气温差和太阳能驱动）比深色屋顶低约30%。计算中考虑了老化的影响（太阳反射率随时间的变化），并提出了新材料和老化材料的太阳吸收率之间的关系。屋顶颜色的分类，相对于他们的太阳能吸收率（暗，中，光和反射），提出了一个快速和简单的评估屋顶颜色的热增益和R值的影响。(C)2008 Elsevier B.V.保留所有权利。
The effect of the roof solar reflectance on the thermal performance of a building is often ignored. However, there are significant differences in heat gain from light and dark-coloured roof surfaces. In this paper an equation for the average daily downward heat flow of a sunlit roof is derived. Using building simulation, it is first shown that the thermal mass of the roof does not significantly affect the overall daily heat gain (although it causes a time lag and reduction in peak heat flow). As a consequence the daily heat gain from the roof may be estimated by integrating the equation for the steady-state downward heat transfer over the day. For north Australia the derived equation suggests that a light-coloured roof has about 30% lower total (air temperature difference and solar-driven) heat gain than a dark-coloured one. The effect of aging (change in solar reflectance with time) is considered in the calculations and a relationship between the solar absorptance of new and aged material is suggested. A classification of roof colours with respect to their solar absorptance (dark, medium, light and reflective) is proposed to enable a quick and simple assessment of the effect of roof colour on the heat gain and R-value. (C) 2008 Elsevier B.V. All rights reserved.