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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 objects.
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 architectural
The Basic Principles of Effective Daylight
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.
Identifies the quality of daylight.
Different shapes, thin linear, L-
shape, U-shape and doughnut need
enough natural light through the
courtyard and thin building
Courtyard and thin building, increase
the nature light and heat distribution
to the sides of building.
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,
The optimum glazing ratio may vary due to individual
factors such as orientation, location, obstructions (View of
sky) and activity/user requirements.
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
Triple glazing, tinted or reflective glass can result in
reduced daylight levels.
Solar transmission =
direct heat from the
Single glazing 88% 83%
Double glazing 77-80% 65-70%
Double glazing -
Triple glazing 70% 40-60%
Table1 shows Window Specification and Light Transmittance
Windows should be high on the wall, widely distributed
and of an optimum area to achieve adequate daylighting.
Figure 4: show Light and shadow distribution produced by different windows
positions, directions and sizes in a room.
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.
Skylights are domed, horizontal or slightly
sloping glazed openings in the roof.
Roof light areas should be limited to a maximum of 12%
of the floor area to reduce excessive heat losses and
Monitor 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 Lighting
Heat gains can be reduced by tilting
roof lights towards the North in
order to utilise diffuse north lighting.
Clerestory 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.
In architectural design, natural daylight is a crucial
component in determining sustainable building and the
quality of an indoor environment.
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
Using appropriate glazing specification for buildings can
result in reduce daylight levels and decrease in energy
use for artificial lighting.
DUXBURY, Liane (2013). Daylight and Modeling Case Studies (2013)
GUZOWSKI, Mary. (2000). Daylighting for sustainable design. New York, McGraw-Hill.
HOURANI, May, and HAMMAD, Rizeq (2012). Impact of daylight quality on architectural space
dynamics: Case study: City Mall--Amman, Jordan. Renewable and Sustainable Energy Reviews,
16 (6), 3579-3585.
LECHNE, Norbert. (2009). Heating, cooling, lighting: sustainable design methods for
architects. 3rd ed., Canada, John Wiley, Hoboken and NJ.
PHILLIPS, Derek. (2004). Daylighting: natural light in architecture. Oxford,
SMITH, Peter F. (2005). Architecture in a climate of change: A guide to sustainable
design. 2nd ed., Oxford, Architectural Press.
YAO, J. and ZHU, N. (2012). Evaluation of indoor thermal environmental, energy and
daylighting performance of thermotropic windows. [online]. Building and Environment, 49,
283-29. Article from Science Direct last accessed 21 August 2013 at: