lighting, types of lighting, effects of lighting

1. NATURAL LIGHTING
The primary source of lighting is the sun. The light received
by the earth from the sun consists of two parts, namely,
direct solar illuminance and sky illuminance. For the
purposes of daylighting design, direct solar illuminance
shall not be considered and only sky illuminance shall be
taken as contributing to illumination of the building interiors
during the day.

2. For good distribution of day light on the working plane in a room,
window height, window width and height of sill should be chosen
in accordance with the following recommendations:
a) In office buildings windows of height 1.2 m or more in the centre
of a bay with sill level at 1.0 to 1.2 m above Window width can
accordingly be adjusted depending upon the required
fenestration percentage of the floor area.
b) It is desirable to have a white finish for ceiling and off white (light
colour) to white for walls. There is about 7 percent improvement
in lighting levels in changing the finish of walls from moderate to
white.
c)Internally reflected light would be the most convenient form of
daylighting. One suitable arrangement is a high level window,
which would admit refleted light to the ceiling if the ceiling is
white, this method would ensure adequate and well diffused
intertior lighting

3. • General Principles of Openings to Afford Good Lighting-
• Generally, while taller openings give greater penetrations, broader openings give
better distribution of light.
• Broader openings may also be equally or more efficient, provided their sills are
raised by 300 mm to 600 mm above the working plane.
• For a given penetration, a number of small openings properly positioned along the
same, adjacent or opposite walls will give better distribution of illumination than a
single large opening.
• Unilateral lighting from side openings will, in general, be unsatisfactory if the effective
width of the room is more than 2 to 2.5 times the distance from the floor to the top of
the opening.
• Openings shall be provided with chajjas, louvers, baffles or other shading devices to
exclude, as far as possible, direct sunlight entering the room.
• Light control media, such as translucent glass panes (opal or matt), tinted glass and
glass blasts are often used.

4. • The Effects of Natural Light-
• Northern light is indirect and can make colors appear darker and less
saturated. The color of northern light is the most diffused light and
remains quite consistent throughout the day. bold colors like green,
yellow, magenta are generally used.
• Colors best for rooms with southern exposure are medium value, or
greyed colors. Rooms with southern exposure benefit from beautiful
warm light but at time it can be too much light that is too intense or
glaring. To solve this problem use colors that are muted with a bit of
grey to absorb a bit of the light so the room feels more comfortable.
• Light that comes from an eastern or western exposure is also
warm.Using colors that are warmer and less muted will help the color
to work even when the sun is not streaming in

5. • If the room width is more than 10 m, windows
should be provided on opposite sides for bilateral
lighting.
• Bilateral Lighting-
• Intent: Windows placed on opposite sides
introduce light from opposite ends.
Quality: Provides relatively even illumination.
Use: To achieve adequate lighting quantity in a
space on opposite ends.
• If the room width is more than 20 m, skylights and
courtyards are provided.
• Skylight-
• Description: Introduces light from above through
aperture in the roof .
Quality: For spaces with demanding visual
requirements, brightness control of a skylight is
necessary based on the shape of the room and
location .
Use: To deliver daylight deep into interior areas of
buildings . Often used with diffusing or prismatic
glazing .
Skylight
Bilateral Lighting

6. • Room-related lighting -Uniform lighting throughout the
room creating roughly the same visual conditions at all
points. This is recommended where the arrangement
of task areas is unknown during the planning phase or
where the arrangement of task areas needs to be
flexible.
• Task area lighting -Different lighting for task areas and
the space around them. This is recommended where a
room contains several task areas which are used to
address different visual tasks and thus have different
lighting requirements. It is also an option where visual
divisions are needed to identify different workplace
clusters.
• Work surface lighting- Workplace luminaires can be
used to supplement “basic lighting” – which can be
either room-related or task area lighting – to achieve a
level of lighting finely tuned to the requirements of the
visual task or personal needs.

7. Artificial lighting may have to be provided-
a) where the recommended illumination levels have to be obtained by artificial
lighting only,
b) to supplement daylighting when the level of illumination falls below the
recommended value, and
c) where visual task may demand a higher level of illumination.
• Artificial Lighting Design for Interiors For general lighting purposes, the
recommended practice is to design for a level of illumination on the working
plane for Office on the basis of the recommended levels for visual tasks is
300-750 lux.
TYPE OF INTERIOR LIGHTING CONCEPT
AND VISUAL TASK
ILLUMINANCE (LUX)
OFFICE ROOM-RELATED
LIGHTING
500
TASK- AREA LIGHTING 500
WORK-SURAFACE
LIGHTING
750