2.3 Simulation Dates and Mimic of U

2.3 Simulation Dates and Mimic of User Behaviour
In this paper we present results for 21 June and 21 December for the South orientation, even though the complete experiment includes 21 March and September and all four compass directions. Testing hours for each of these dates are 10, 12, 14 and 16 h. The CIE intermediate sky with sun was applied, since it was determined to be suitable for the local conditions [1].
The aim of the study is to integrate qualitative and quantitative evaluations, since presenting illuminance data only can be misleading. Users will react to provide themselves with visual comfort if they are faced with unfavourable situations, as it occurs in completely glazed offices lacking curtains [6]. Therefore, a movable shading device such as a venetian blind was also included in the study.
Computer simulations of human response to natural light through shading devices like internal blinds need careful understanding for adequate modelling [7]. Here it is simplified as follows: blinds are assumed to be lowered completely in the open, horizontal position when the Radiance simulation picture shows direct solar penetration (sunspot) over the office’s floor beyond 1m from the view window. These blinds do not cover the clerestory part of the elements.
2.4 Glare Analysis
Even though it is a complex qualitative issue that needs further research and understanding, glare from large natural sources can be numerically quantified through scales such as the daylight glare index (DGI) [8] which is used in this study.
Radiance assigns luminance values to the pixels composing the pictures it generates, making feasible the evaluation of glare indexes through image analysis with such information. This method has been used by Schiler [9] to detect post-occupancy glare conditions by statistically analyzing pixel luminance information from digital cameras and is gaining acceptance as a research method [10].