Investigating the role of three types of horizontal openings in industrial buildings concerning exploitation of daylight and optical comfort

Used properly, daylight can have lots of benefits, not only in visual comfort but also in reduction in energy consumption as well as improving H&S at work. [L. Bellia et al,2013]. This paper identifies the effects of different roof types (i.e. saw tooth roof, skylight and monitor) and opening geometries to the overall ingress indices of natural light and their effectiveness as complementary or exclusive light sources in an industrial environment in the Athens-Greece region. The choice of building has been made as to be a representative unit of Greek domestic industrial facilities. As such, the selection to identify daylight properties in a structural module rather than a bespoke industrial facility has been made. The dimensions selected are standard dimensions frequently used in industrial expansion and new development projects. The methodology followed was based on a multiparametric approach consisting of 3 different roof opening arrangement types with different distances ranging from 1 to 20m and height aspect ratios of 1 to 4. In the absence of existing strong LEED criteria for this kind of structures it has been deemed necessary to calculate a large number of relevant indices for tracing dependencies. The most prominent results have been selected for further simulation for three distinct dates 21/03, 21/06 and 21/12 representing equinox as well as the summer and winter solstices respectively. For those, hourly simulations covering the work hours from 07.00 to 17.00 (those values selected over the usual 08.00-18.00 to better represent Greek workday hours) and the relevant annual sun exposure (ASE) indices have been extracted. In total 648 different simulations have been performed with standard overcast sky while an additional series of 300 clear sky simulations to represent 10 working hours for the 3 selected days. Data were obtained through the use of Diva for Rhino and results indicated significant contribution of the type of opening in daylight acting at workbench height as light source. The superiority of north opening orientations and partially indirect light ingress (i.e. saw tooth and monitor roof opening arrangements) that avoid high glare values and promote light uniformity with reduced illuminance spikes has been revealed. On the other hand, skylights have been deemed quite an inadequate arrangement yielding highly concentrated high illuminance levels. Numerical results indicated reductions in ASE of a 55% (max) between the E-W and N-S orientations for Monitor roofs; an increase of 22% (max) between N and S and 2% (max) between E and W orientations for Saw Tooth roofs; while Skylights raised optical discomfort behaviour with ASE values ranging from 2% to >90%. Overall, a strong indication of Saw Tooth roofs as the best choice of natural light sources for industrial buildings at the selected geographic location.