This document discusses daylighting systems that use reflectors to deflect daylight further into interior spaces. It begins by introducing daylighting and its benefits, such as energy savings. It then describes various daylighting techniques including windows, clerestories, sawtooth roofs, skylights, atriums, translucent walls, and remote distribution methods like light shelves and prisms. Key terms related to daylighting performance are also defined, such as daylight factor, illuminance level, U-value, shading coefficient, and reflectance value. Emerging smart glass and solar lighting technologies are mentioned. The document concludes with considerations for daylighting design and evaluation methods.

1. DAYLIGHTING SYSTEMS
Reflectors That Deflect Daylight into The Depth of Room
Submitted to :- Prof Himmi Gupta Submitted by:- Ankaj Kumar
Roll No . 202304
ME ( CTM )

2. INTRODUCTION
• Daylighting is the practice of placing windows, other openings, and reflective surfaces so
that sunlight (direct or indirect) can provide effective internal lighting reduced use of
artificial (electric) lighting or from passive solar heating
• Energy savings can be achieved
• daylight harvesting.
• direct sunlight and diffused daylight.
• Ground reflected light also contributes to the daylight. Each climate has different
composition of these daylights and different cloud coverage, so daylighting strategies vary
with site locations and climates

3. TYPES
1.WINDOWS
• Windows are the most common way to
admit daylight into a space.
• Their vertical orientation means that
they selectively admit sunlight and
diffuse daylight at different times of
the day and year.

4. a) CLERESTOREYS
• These are high, vertically placed
windows. They can be used to increase
direct solar gain when oriented towards
the equator.
.• These walls are placed so as to reflect
indirect light to interior areas where it is
needed.

5. b) SAWTOOTH ROOF
• Another roof-angled glass alternative is a sawtooth
roof (found on older factories). Sawtooth roofs have
vertical roof glass facing away from the equator side of
the building to capture diffused light (not harsh direct
equator-side solar gain).
• The sawtooth roof’s lighting concept partially
reduces the summer “solar furnace” skylight problem,
but still allows warm interior air to rise and touch the
exterior roof glass in the cold winter, with significant
undesirable heat transfer

6. 2. SKYLIGHTS
• Skylights are light transmitting SKYLIGHTSfenestration
(products filling openings in a building envelope which also
includeswindows, doors, etc.) forming all, or a portion of, the
roof of a building space.
• Skylights are the most effective source of daylight on a unit area
basis.

7. 3. ATRIUM
• An atrium is a large open space
ATRIUMSlocated within a building. It is
often used to light a central circulation
or public area by daylight admitted
through a glass roof or wall. 7]

8. 4. TRANSLUCENT WALLS

9. 5. REMOTE DISTRIBUTION
• LIGHT REFLECTORS AND SHELVES
• PRISMS
• LIGHT TUBES

10. a) LIGHT REFLECTORS
AND SHELVES
• A white or reflective metal light shelf
outside the window.[Usually the window
will be protected from direct summer
season sun by a projecting eave.
• The light shelf projects beyond the
shadow created by the eave and reflects
sunlight upward to illuminate the ceiling.

11. b) PRISMS
• Prisms that used total internal
reflection to throw light sideways,
lighting the deeper portions of a room,
later became popular.
• They were and are used in the upper
portions of windows.

12. c) LIGHT TUBES
• Another type of device used is the light
tube, also called a tubular daylighting
device (TDD), which is placed into a
roof and admits light to a focused area
of the interior.
• These somewhat resemble recessed
ceiling light fixtures. They do not allow
as much heat transfer as skylights
because they have less surface area.

13. TERMINOLOGY

14. 1. DAYLIGHT FACTOR
• The daylight factor (DF) is commonly used to determine the ratio of internal light
level to
external light level and is defined as follows:
DF = (Ei / Eo DF = (Ei / Eo) x 100% ) x 100%
• where: Ei = illuminance due to daylight at a point on the indoors working plane
Eo = simultaneous outdoor illuminance on a horizontal plane from an
unobstructed hemisphere of overcast sky.

15. • <2: not adequately lit – artificial
lighting will be required.
• 2 – 5: adequately lit but artificial
lighting may be in use for part of the
time.
• >5: well lit – artificial lighting not
required except at dawn and dusk.
However glare and solar gain may cause
problems

16. 2. ILLUMINANCE LEVEL (lux)
• The illuminance level (lux) at any point
being considered is the sum of these: Lux
= SC + ERC + IRC
• Each of these components may be
adjusted by the designer (e.g. the
reflectivity of internal surfaces) to
achieve the required level of lighting
• the sky component (SC): direct light
from a patch of sky visible at the point
considered
• the externally reflected component
(ERC): the light reflected from an
exterior surface and then reaching the
point considered
• the internally reflected component
(IRC): the light entering through glazing
and reflected from an internal surface.

18. 3. U-VALUE, SHADING
COEFFICIENT, VISIBLE
TRANSMITTANCE
• The simplest method to maximize daylight within a space is to
increase the glazing area. Such materials are dependent on the
following criteria-
–U VALUE : represents the rate of heat transfer due to temperature
difference through a particular glazing material.

19. • SHADING COEFFICIENT: a ratio of solar heat gain of a given
glazing assembly compared to double-strength, single glazing. (A
related term, solar heat gain coefficient, is beginning to replace the
term shading coefficient.)
• VISIBLE TRANSMITTANCE: a measure of how much visible light
is transmitted through a given glazing material

20. 4. REFLECTANCE
VALUE
• Reflectance values from room surfaces
will significantly impact daylight
performance and should be kept as high as
possible. It is desirable to keep
ceiling reflectances over 80%,
walls over 50%, and
floors around 20%. Of the various room
surfaces, floor reflectance has the least
impact on daylighting penetration.

23. TECHNOLOGY

24. USE OF SMART GLASS
• Smart glass can be switched between a transparent state and a state
which is opaque, translucent, reflective, or retro-reflective by applying
a voltage to the material, or by performing some simple mechanical
operation.
• Windows, skylights, etc., that are made of smart glass can be used to
adjust indoor lighting, compensating for changes of the brightness of
the light outdoors and of the required brightness indoors

25. SOLAR LIGHTING
• HELIOSTATS

26. HYBRID
SOLAR
LIGHTING

27. INTEGRATION WITH ELECTRIC
LIGHTING CONTROLS
• A successful daylighting design not only optimizes architectural features, but is also
integrated with the electric lighting system. With advanced lighting controls, it is now
possible to adjust the level of electric light when sufficient daylight is available. Three
types of controls are commercially available:
– Switching controls: on-and-off controls that simply turn the electric lights off when
there is ample daylight.
– Stepped controls: control individual lamps within a luminary to provide intermediate
levels of electric lighting.
– Dimming controls: continuously adjust electric lighting by modulating the power
input to lamps to complement the illumination level provided by daylight.

28. OTHER LIGHTING CONTROL
SCHEMES
• • use of Occupancy controls: using infrared, ultrasonic, or micro-wave
technology, occupancy sensors respond to movement or object surface
temperature and automatically turn off or dim down luminaries when rooms
are left unoccupied. Typical savings have been reported to be in the 10% to
50% range depending on the application.
• • Timers: these devices are simply time clocks that are scheduled to turn
lamps or lighting off on a set schedule. If spaces are known to be
unoccupied during certain periods of time, timers are extremely cost-
effective devices

29. EVALUATION METHODS
1. FIELD MEASUREMENTS
2. COMPUTATIONAL SIMULATIONS

30. DESIGN CONSIDERATIONS

31. • Increase perimeter daylight zones- to maximize the usable daylighting area.
• Allow daylight penetration high in a space. Windows located high in a wall or in roof monitors and
clerestories will result in deeper light penetration and reduce the likelihood of excessive brightness.
• Reflect daylight within a space to increase room brightness. A light shelf, if properly designed, has
the potential to increase room brightness and decrease window brightness.
• Slope ceilings to direct more light into a space. Sloping the ceiling away from the fenestration area
will help increase the surface brightness of the ceiling further into a space.
• Avoid direct beam daylight on critical visual tasks. Poor visibility and discomfort will result if
excessive brightness differences occur in the vicinity of critical visual tasks

32. • Filter daylight. The harshness of direct light can be filtered with vegetation, curtains, louvers,
or the like, and will help distribute light.
• Understand that different building orientations will benefit from different daylighting
strategies; for example, light shelves-which are effective on south facades-are often ineffective
on east or west elevations of buildings
• Simple sidelighting strategies allow daylight to enter a space and can also serve to facilitate
views and ventilation.
• Typically, the depth of daylight penetration is about two and one-half times the distance
between the top of a window and the sill.

33. SPECIAL CONSIDERATIONS

34. • Since a daylighting system operates differently than a system used in a
conventional building, occupants should be trained on the operation of the
switches (if any are provided), on the overall design intent, and on the expected
functionality of the daylighting system. In a conventional building,
• Provide flexibility in the furniture system and programming to allow for
variability in occupant tolerance and illumination requirements.

35. THANKING YOU