A Holistic Approach for Improving Visual Environment in Private Offices

Visual comfort is one of the main priorities in designing working and living environments. An efficient design of an office space however should also take into account its energy performance, and the connection to the outdoors. The latter is a poorly studied but critical factor connected to the overall visual satisfaction in the interior. While new designs offer freedom to the architects in terms of orientations, window-to-wall ratios and high performance glazing systems, existing spaces require more targeted and effective retrofit solutions, mostly connected to shading devices and automatic control systems or even the potential adjustment of the positional layout in the interior. Glare from daylight is a common issue in building perimeter zones with large facades that highly affects productivity and occupant comfort, therefore its mitigation should be considered as a priority. Then, maximizing the lighting energy performance or the degree of connection to the outdoors should be secondary decisions connected to the use of the space. Several indicators have been developed to quantify the degree of visual discomfort, and Daylight Glare Probability (DGP) is widely accepted as an appropriate index. However, in this study, due to limitations of the applicability of DGP in cases with the sun visible through roller shades, an alternative criterion is being used, based on thresholds for the direct and total vertical illuminance on the eye. In compliance with IES Standard LM-83-12, the continuous daylight autonomy is used to assess the lighting energy performance of the space, while for the connection to the outdoors, the newly developed Effective Outside View index is extended in order to quantify the case of dynamic shading systems. The triple visual environment criterion allows a holistic evaluation of the visual environment in private offices with roller shades.