A Comparative Analysis of the Visual Comfort Performance between a PCM Glazing and a Conventional Selective Double Glazed Unit

Abstract

The performance of a Double Glazing Unit (DGU) with a Phase Change Material (PCM) layer embedded in the cavity was analyzed in terms of the visual comfort perceived by the occupants. The analysis was carried out through a set of simulations, performed by the Radiance engine managed through Honeybee. As an input for the simulations, the visible transmittance Tv of PCM in solid (diffusing) state was used, based on previous laboratory measurements. The simulations were run for several specific times of the year: The two solstices and the autumn equinox, for different hours during the day. Other variables investigated were the site (Östersund, 63.2° N; Turin, 45.2° N; Abu Dhabi, 24.4° N), the room orientation (south; west), and the sky conditions (clear sky with sun; overcast). For comparative purpose, the simulations were repeated for the same boundary conditions in a room equipped with a selective glazing, with a Tv of 0.5. For each case, the visual comfort perceived by the occupants has been analyzed in terms of Daylight Glare Probability (DGP) in two different points in the room and of “Spatial Useful Illuminance” (percent of work plane points where the illuminance lies in the range 100–3000 lx). The results showed that the glazed package with PCM in most cases admits more daylight into the room, resulting into an increased glare (DGP values), but also in lower Spatial Useful Illuminance values.