2017 - Daylight Symposium
"Quantitative and qualitative assessment of visual comfort in offices" Laura Thuillier
Energy Performance of Buildings and Daylighting
Chantereine Research and Development Center (CRDC) of Saint-Gobain
Lecture from the 7th VELUX Daylight Symposium “Healthy & climate-friendly architecture– from knowledge to practice” that took place in Berlin on 3-4 May 2017. For more information visit http://thedaylightsite.com
“Quantitative & qualitative assessment and improvement of visual comfort in offices” by Laura Thuillier, Daniele Constantini, Eloise Sok. While increasingly highlighted in new construction, daylight still represents a largely unexploited resource in existing buildings, for saving energy and improving occupant’s comfort. It is well known that daylighting has a positive impact on people health and wellbeing; this also stands true for offices occupants who benefit of a productivity and concentration improvement due to well-daylit workplaces. In this frame, there is a need for a nonintrusive daylighting diagnosis of ex-isting offices in order to help the discussion about comfort with designers, owners, and occupants.
Actually, multiple simulation tools are today available and used in building industry to assess daylight levels in a space. Measurements tools also exist but are usually complex, very intrusive and may be only handled by experts. To easily perform measurements, Saint- Gobain developed a wireless and lowcost setup for illuminance measurements which, due to its small footprint and ease of installation, is particularly suitable for occupied offices. Moreover, in order to thoroughly assess the visual dimension of working environment on employees, we propose to consider not only daylighting but to extend the diagnosis to a more complete characterization. We decided to adopt in our research a human-centric approach, including all aspects of visual comfort. We found four main indicators to define visual comfort: natural light, artificial light, views (outside and inside), and quality of interior space.
This paper aims at introducing a quick methodology and protocol to assess overall visual comfort by an expert in about 15 minutes. The proposed diagnosis is a tool with 40 steps of evaluation that guides the expert towards a quantitative evaluation of the four representative indicators of visual comfort. This protocol allows obtaining an expert diagnosis which fits the occupant perception of visual comfort. All steps were calibrated thanks to the collaboration with occupants, using indepth sociologic interviews in some reference offices. We will present the visual comfort assessments of two offices, performing measurements with the new light meters setup and the quick diagnosis tool. The result of the expert diagnosis is particularly useful to forecast discomfort areas and fuel a discussion around possible technical solutions to improve visual comfort.
In a second time, we will show the use of this diagnosis to illustrate a test case in which offices were retrofitted with SageGlass® electrochromic glazing. In particular the expert diagnosis was used to underline key initial concerns related to glare, quality of the view and artificial lighting use. Then, the effect of electrochromic glazing was quantified thanks to measurements with the wireless setup and modelling. In conclusion, the test case demonstrates the possibility to improve overall visual comfort, by ensuring effective glare protection and preserved views while at the same time maximizing daylight admission, to ensure a high energy performance.
Laura Thuillier is part of the Energy Performance of Buildings and Daylighting group at the Chantereine Research and Development Center (CRDC) of Saint-Gobain since 2016 as a Development Engineer. Before that, she was an intern for the modeling Competence Center at CRDC. She received a Master of Engineering in Materials Science from the Ecole Européenne d’ingénieurs en génie des matériaux in 2015. Laura is in charge of Visual Comfort and Daylighting activities at CRDC, developing measurement and modeling capacities as well as monitoring comfort criteria with respect to energy performance and daylighting in green building labels and the academic community.