Building Science daylighting in building

daylighting

1. BUILDING SCIENCE 2A
Lecture 1: Day-ligthing in Building design
BUILDING SCIENCE 2A
Lawrence Ogunsanya
[email protected]
BUILDING SCIENCE 2A

2. Definition: Day-lighting L
Is the use of indirect natural lighting to illuminate the interior of buildings
reducing the need for electric lighting L
Lighting of the interior of a building by natural m eans; for example, by
windows or skylights. L
It is the practice of placing windows or other openings a nd reflective
surfaces so that during the day natural light provides ef fective internal
lighting
L
Day
-
lighting is considered a sustainable building strategy in that it can
BUILDING SCIENCE 2A
L
Day
-
lighting is considered a sustainable building strategy in that it can
reduce reliance on artificial light (and reduce energy use in the process)
and when well designed, contributes to occupant comfort a nd
performance.
L
The use of natural light to supplement or replace arti ficial lighting.
Strategies include the proper orientation and placemen t of windows, use
of light wells, light shafts or tubes, skylights, clerestory windows, light
shelves, reflective surfaces, and shading, as well as the use o f interior
glazing to allow light into adjacent spaces.
BUILDING SCIENCE 2A

3. Day-lighting design pitfalls L
Incorrectly designed windows and/or skylights
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4. Day-lighting design pitfalls
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5. Day-lighting design pitfalls
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6. Day-lighting design pitfalls
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7. Day-lighting design pitfalls L
Glare: Discomfort in the eye and depression of central v ision
produced when a bright light enters the field of vi sion
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8. Advantages of Day-lighting L
All buildings receive daylight. A natural well lit building, however, is
specifically designed to efficiently use daylight t hrough adapted
components and control strategies.
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9. L
Improved lighting quality: Lighting quality refers to visual
performance, visual comfort and ease of seeing. L
Better occupant comfort and health: Another aspect of daylight
is its variability throughout the day, leading to p eaked visual
interest. The eyes adapt easily to gradual illumina tion changes,
changes not easily attainable with artificial light .
BUILDING SCIENCE 2A
Benefits of Day-lighting
changes not easily attainable with artificial light .
L
Increased productivity and retail sales: People exposed to
daylight are more productive and efficient. L
Reduced auxiliary lighting load: Day-lighting has become a
major feature in energy efficient design. L
Reduced cooling load: Compared with electrical lighting,
daylight delivers more of its energy as visible lig ht and less as
heat.
L
Reduction in electricity demand during the day
BUILDING SCIENCE 2A

10. Design Principles and Concepts L
Access to light
L
Buildings should be arranged on site to ensure that they have
good access to daylight and do not shade close neig hbours. L
Obstructions in front of windows can severely reduc e the quality of
daylight in spaces. L
The quality of daylight in a space relates to the v isible sky angle
BUILDING SCIENCE 2A
L
The quality of daylight in a space relates to the v isible sky angle measured from the centre of a window on an external wall. The
larger this angle the better the daylight quality w ill be in the space. L
The no skyline position is the location on the work ing plan (0.85m
above floor in residential and L
0.7m above floor level in offices) where the sky ca n no longer be
seen. Space to the interior of this will usually re quires
supplementary electrical lighting.
BUILDING SCIENCE 2A

11. Design Principles and Concepts
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12. L
Building Orientation
L
In general, the long section of buildings should be orientated to +/-
15 degrees North. L
In addition, the extent of the façade facing north should be
maximized and the length of façade facing east and west
minimised.
L
This enables good access to sunlight for the north façade, good
BUILDING SCIENCE 2A
Design Principles and Concepts
L
This enables good access to sunlight for the north façade, good access to daylight through the north and south faça des and
reduces unwanted heat gain from early morning and late
afternoon sunshine on the east and west façades.
BUILDING SCIENCE 2A

13. BUILDING SCIENCE 2A
Design Principles and Concepts
BUILDING SCIENCE 2A

14. L
Building form
L
Long and narrow footprints are better than square o nes for access
to daylight. Buildings can be arranged as a series of wings to
minimize land requirements while still allowing acc ess to daylight.
BUILDING SCIENCE 2A
Design Principles and Concepts
BUILDING SCIENCE 2A

15. L
Depth of the buildings
L
The depth of the building should be limited to ensu re that internal
spaces that cannot be day lit are limited in area. L
A general rule of thumb is that daylight quality wi ll be reasonable
within the space 2h from a window, where h is the h eight of the
head of the window from floor level (see figure bel ow).
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Design Principles and Concepts
BUILDING SCIENCE 2A

16. L
Use of Atriums
L
Use atriums to maximize core daylight. The figure b elow illustrates
that by increasing the footprint of the building sl ightly, an atrium
can provide full floor daylight.
BUILDING SCIENCE 2A
Design Principles and Concepts L
Window Placement
L
Use strip windows for uniform office lighting. A lo ng strip of
windows, rather than individual punched windows wil l provide
sufficient lighting to a room without lighting cont rasts
L
work areas should be in front of windows for north- facing offices
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17. BUILDING SCIENCE 2A
Design Principles and Concepts L
Types of side lighting
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18. L
Light Shelves
L
Light shelves are horizontal reflectors placed unde r a high window
that bounce light deep into a room. L
If positioned correctly, light shelves can improve light distribution
in a space by reducing glare and by providing more even light
distribution.
BUILDING SCIENCE 2A
Design Principles and Concepts
distribution.
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19. BUILDING SCIENCE 2A
Design Principles and Concepts
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20. L
Top lighting
L
The main advantages of top lighting over side light ing are roof
openings can provide lighting over larger areas. L
whereas typical side lighting is restricted to abou t the first 3 to 5
meters of room space L
the possibility of uniform and high illumination le vels (especially
BUILDING SCIENCE 2A
Design Principles and Concepts
with skylights).
L
Clerestories and monitors offer increased opportuni ty to diffuse
direct incoming radiation off the ceiling or shelve s.
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21. BUILDING SCIENCE 2A
Design Principles and Concepts
BUILDING SCIENCE 2A

22. BUILDING SCIENCE 2A
Design Principles and Concepts
BUILDING SCIENCE 2A

23. BUILDING SCIENCE 2A
Day-lighting
BUILDING SCIENCE 2A

24. Questions
History of Urban settlements History of Urban settlements