Natural light from the sun
is one of the irreplaceable energy source for people’s daily life. The
significance of natural light in human life becomes more apparent when we are
deprived of light or exposed excessive light. It has been proven that both lack
of daylight and exposure to natural light in buildings have negative
psychological and physiological effects on the health, well-being and
performance of humans. Excessive light explosion causes reflected glare,
undesirable visual comfort and overheating. Consequently the deterioration of
room’s atmosphere and energy balance causes occupants to be uncomfortable, the
lack of concentration and to get tired easily. In the absence of sufficient
daylight, artificial lighting is needed but studies proved that the typical
symptoms such as headaches, fatigue and eyestrain increase in proportion to the
use of artificial lighting. Therefore, people instinctively tend to prefer
daylit areas instead of artificially lit areas.

In the design process of
sustainable built environments, daylighting also plays a significant role in
the energy savings since it allows the use of daylight to be maximized in an indoor
environment and to reduce the electrical energy demand for lighting and cooling
of buildings. For a better daylight performance both quantitative and the
qualitative parameters should be considered.

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Various factors impact the
interior daylight illuminance such as location, orientation, day and time, sky
cover, room geometry, window size and presence of shading. As a rule of thumb,
conventional windows can adequately and effectively illuminate a room to a
depth of 1.5 times the height of the window above the floor level, rest of the
room still need to be illuminated with additional artificial lighting. Applying
large windows provides higher illuminance at the back of the room and thus reduces
the use of artificial lighting, but this cause a disproportional amount of
solar radiation into the front part of the room and resulting in an increase in
cooling loads. In addition, the non-uniform illuminance distribution throughout
the working plane can result visual problems associated with glare. Thus,
determination of right balance between window size and room geometry is
required.

Conventional daylighting
design components partially control direct sunlight and glare near the
perimeter zones but their characteristics are insufficient when it comes to
illuminating deep spaces and providing adequately uniform lighting, therefore, variety
of innovative daylighting systems have been developed to improve the usage of
daylight. These systems rely on increasing illuminance further from windows to
areas where it is required by redirecting incoming sunlight towards the ceiling
plane. This proper handling of diffuse/direct daylight also avoids probability
of glare for occupants seated near the window and distributes daylight evenly.

In this study, application
of a daylighting system is proposed to enhance the visual conditions of
side-lighted deep plan room based on the field and simulation measurements. The
aim is primarily to investigate performance of prismatic panels in providing
sufficient daylight as deeply as possible into the space and preventing
negative impacts of natural light on occupants. The second aim is to find a
balance (or relation?) between window size and room geometry when prismatic panes installed. This study offers a new approach with consideration
of innovative daylight redirecting systems for requirements mentioned in the
standards about daylighting in buildings. Thus, study can be used as a guide in
the design phase by all related professionals.