Monitoring results of an interior sun protection system with integrated latent heat storage

An interior sun protection system consisting of vertical slats filled with phase change material (PCM) was monitored from winter 2008 until summer 2010. While conventional interior sun protection systems often heat up to temperatures of 40 °C or more, the monitoring results show that the surface temperature on the interior side of the PCM-filled slats hardly ever exceeded the PCM melting temperature of 28 °C even in case of long-term intense solar radiation. As long as the PCM is not fully melted, the latent heat storage effect reduces the solar heat gain coefficient (g-value) of the sun protection system to 0.25 for a totally closed blind, and 0.30 for slats set at 45° (the g-values of the same system without PCM are 0.35 and 0.41, respectively). This reduced the maximum air temperature in the offices by up to 2 K in contrast to a reference room with a comparable conventional blind. The sun protection system with PCM therefore considerably improves thermal comfort. In order to discharge the PCM, the stored heat must be dissipated during the night. In climates with sufficiently low outside air temperatures, this is best achieved using a ventilation system in combination with tilted windows.

► Interior sun protection system with PCM was monitored in four test rooms.
► Interior sun protection system with PCM reduces operative room temperature by up to 2 °C.
► Interior blind with PCM stays cool even in case of direct solar radiation.
► PCM in interior sun protection system improves thermal comfort.