Daylighting for sustaianable Design Buildings

2. Outline

3. 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 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
spaces.
Figure 1

4. The Basic Principles of Effective Daylight
Design
 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.

5.  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.
Figure 2

6.  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 activity/user requirements.

7.  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 daylight levels.

8. 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

9.  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.
Figure 3

10.  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 Lighting:
Skylights:
 Skylights are domed, horizontal or slightly
sloping glazed openings in the roof.
Figure 5
 Roof light areas should be limited to a maximum of 12%
of the floor area to reduce excessive heat losses and
gains.

11. Monitor Lighting
 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.
Figure 6
Figure 7

12. Clerestory Windows
 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.
Figure 8

13. Conclusion
 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
needs.
 Using appropriate glazing specification for buildings can
result in reduce daylight levels and decrease in energy
use for artificial lighting.

14.  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,
Architectural Press.
 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:
http://www.sciencedirect.c.
References