Comfort Considerations in Net ZEBs: Theory and Design - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 132

daylight availability, views to the outdoors, and natural ventilation potential
(Leaman and Bordass, 2005). However, in order to fully realize the energy
savings from daylighting, manual or automated lighting controls must allow
for it to be properly integrated as a complement to electric lighting.
Fig. 3.5 Three-section façade concept and three-section façade of the
Engineering, Computer Science and Visual Arts Integrated Complex (EV)
at Concordia University, Montreal, Canada
This section provides an overview of visual comfort issues with emphasis on
their quantification, including illuminance- and luminance-based metrics.
3.3.2 Adaptation Luminance
For the eye to be able to function well, it has to adapt to the prevailing
luminance conditions (adaptation luminance) by constricting and dilating
the iris, neurologically, and photochemically (Rea, 2002). Adaptation to
varying transient luminance takes some time (seconds to minutes,
depending on the magnitude of the luminance shift) and varies through
the period of a task, either because of the eye movement from one point
to another or due to daylight variation (Osterhaus, 2009). If high contrast
conditions are present, the eye stresses to adapt, which translates to feelings
of annoyance (discomfort glare). Hence, the luminance ratio between the
visual task, its adjacent surroundings, and more distant surfaces is
recognized as a major, if not the most important, determinant for a
glare-free environment (ISO, 2006). Depending on the environment, the
luminance levels might significantly vary from one viewpoint to another.