Field thermal performance of naturally ventilated solar roof with PCM heat sink

• Published in: Solar energy 2012-09, Vol.86 (9), p.2504-2514
• Main Authors: Kośny, Jan, Biswas, Kaushik, Miller, William, Kriner, Scott
• Format: Article
• Language: English
• Subjects: Building energy; Building-integrated PV; Heat; Insulation; Metal roofs; Phase change material; Photovoltaic cells; Solar energy; Thermal energy; Thermal insulation
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2012.05.020

► Attic using dynamic roof deck with PCM heat sink was tested in field conditions. ► The winter test data demonstrated 30% reduction in roof-generated heating loads. ► Summer cooling load reductions were about 55% comparing to conventional attic. ► PCM cycling was observed during 2/3rd of the total number of summer days. For decades, residential and commercial roofs have been considered a prime location for installation of building integrated solar systems. In climatic conditions of East Tennessee, USA, an experimental solar roof was tested during 2009/2010, by a research team representing Metal Construction Association (MCA), and a consortium of building insulation companies, photovoltaic (PV) manufacturers, and energy research centers. The main objective was to thermally evaluate a new roofing technology utilizing amorphous silicon PV laminates integrated with the metal roof panels. In order to mitigate thermal bridging and reduce roof-generated thermal loads, this novel roof/attic assembly contained a phase change material (PCM) heat sink, a ventilated air cavity over the roof deck, and thermal insulation with an integrated reflective surface. During winter, the experimental roof was expected to work as a passive solar collector storing solar heat absorbed during the day, and increasing overall attic air temperature during the night. During summer, the PCM was expected to act as a heat sink, reducing the heat gained by the attic and consequently, lowering the building cooling-loads. In this paper, field thermal performance data of the experimental PV-PCM roof/attic system are presented and discussed. Performance of the PV-PCM roof/attic is evaluated by comparing it to a control asphalt shingle roof. The test results showed about 30% heating and 50% cooling load reductions are possible with the experimental roof configuration.