Daylighting for Sustainable Design
Basic Principles of Effective Daylight DesignIntroduction
Daylighting: Source of heating and lighting.Daylight enters a
building via four primary mechanisms; Direct sunlight - Clear sky -
Clouds (diffuse light) - Reflections from ground and nearby
Daylight elements such as good lighting, window size and view
out have a pivotal role in emotional satisfaction (Hourani and
Hammad, 2012).Crucial factor in determining sustainable
architectural design and give a sense of pleasure in the
The Basic Principles of Effective Daylight Design1. Site
Orientation:The orientation of buildings is important, if the
length of the building is oriented in an east-west axis, it will
allow penetration of passive heating or cooling within the building
on a seasonal basis (Guzowski, 2000).
A north-south facade is better as it allows penetrating a good
daylight by avoiding glare and overheating.
Designers could define which rooms need direct or indirect
sunlight and require the quantity of heat or heat loss.
2.Form of Building:Identifies the quality of daylight.
Different shapes, thin linear, L- shape, U-shape and doughnut
need enough natural light through the courtyard and thin
Courtyard and thin building, increase the nature light and heat
distribution to the sides of building.
3. Glazing Ratio:Glazing provides natural daylight but also
allows unwanted summer solar gains and winter heat losses.
The larger the windows the more daylight and solar gain will
enter - but the larger the heat losses will be.
Recommended glazing ratios are generally between 25-50% of the
external wall of the daylight space (Duxbury, 2013).
The optimum glazing ratio may vary due to individual factors
such as orientation, location, obstructions (View of sky) and
4 Glazing Specification:The type of glazing has a direct
influence on thermal performance and daylight levels.
Triple glazing gives greater thermal comfort because its
internal temperature is closer to the internal air conditions.
Triple glazing, tinted or reflective glass can result in reduced
Window specifications Daylight transmission Solar transmission =
direct heat from the sun
Single glazing 88% 83% Double glazing 77-80% 65-70% Double
glazing - tinted 29% 39% Triple glazing 70% 40-60%
Table1 shows Window Specification and Light Transmittance
5 Window Height and Location:Windows should be high on the wall,
widely distributed and of an optimum area to achieve adequate
Figure 4: show Light and shadow distribution produced by
different windows positions, directions and sizes in a room.Figure
6 Options for Overhead Daylighting:Horizontal rooflights admit
more daylight per square metre of glazed area than do vertical
windows, a horizontal rooflight is proportionately three times more
effective as a source of daylight than a vertical window. Roof
Skylights are domed, horizontal or slightly sloping glazed
openings in the roof.Figure 5Roof light areas should be limited to
a maximum of 12% of the floor area to reduce excessive heat losses
Monitor LightingMonitor lighting can be used to reduce glare,
heat gains, and protect internal spaces from direct sunlight, by
providing an opaque roof and overhang above the glazing.
Saw Tooth LightingHeat gains can be reduced by tilting roof
lights towards the North in order to utilise diffuse north
Figure 6Figure 7
Clerestory WindowsClerestory windows are usually situated at a
high level (near the ceiling of the room) - always above eye
level.They provide an effective source of natural light and
ventilation whilst reducing glare.Figure 8
ConclusionIn architectural design, natural daylight is a crucial
component in determining sustainable building and the quality of an
Many significant factors determine the quality and quantity of
daylight; site orientation, form of building and type, size,
location of the glazing space. The successful design of healthy
building is controlling the natural lighting and distribute in
spaces according to their needs.
Using appropriate glazing specification for buildings can result
in reduce daylight levels and decrease in energy use for artificial
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SMITH, Peter F. (2005). Architecture in a climate of change: A
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from Science Direct last accessed 21 August 2013 at:
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