Effect of internal woven roller shade and glazing on the energy and daylighting performances of an office building in the cold climate of Shillong

Abstract

The energy and visual performances of the façades are defined by many parameters including façade size, properties of glazings and shadings, and their arrangements as well as control strategies. In this study, a number of combinations of internal woven roller shades and four double glazings have been proposed and assessed in integrated manner in order to improve the energy efficiency and visual comfort in new or existing office buildings. Office rooms facing south, east, north and west have been simulated for cold climate, by varying glazed areas and proposed glazing and shading alternatives. Results have been calculated, compared and analyzed in terms of the energy consumptions, energy saving potentials, daylight autonomy, useful daylight illuminance and discomfort glare free time, for each of the combina-tions. Simulation results show that the choice of glazing and shading alternatives can have substantial impact on energy and visual performances of the office space. Regardless of façade orientation, the max-imum energy saving is achieved for a window-to-wall ratio (WWR) of 30%. Saving potential decreases significantly for larger glazed area and for each façade orientation. For all façade orientations and glazed areas (except for 30% WWR in the north wall), a bare low-e coated double glazing (U = 1.616 W/m2 K, SHGC = 0.209, sv = 0.301) is found to be the most energy efficient choice. For 30% north glazing, the energy efficiency can be maximized with a different bare low-e coated double glazing (U = 1.628 W/m2 K, SHGC = 0.370, sv = 0.581). Moreover, glare affected time, daylight autonomy and useful daylight illuminance in the office spaces with these glazing choices are estimated P50%, between 46% and 99%and in the range of 53–88% respectively. Also, the visual comfort can further be improved just by deploy-ing even a highly transparent fabric (50% transmittance, 20% reflectance, 45% average openness) as an interior roller shade with these glazing choices.