Lighting: artificial and natural: effect on health and environment

1. LIGHTING

2. Lighting
“Lighting or illumination is the deliberate
application of light to achieve some
aesthetic or practical effect.”

3. Requirements of good lighting
• Sufficiency: 15 to 20 foot
candles-basic minimum for
satisfactory vision
• Distribution: uniform with same
intensity
• Absence of glare
• Absence of sharp shadows
• Steadiness
• Colour of light
• Surroundings
Wall-mounted light with
shadows
Low-intensity lighting and haze in a concert hall
allows laser effects to be visible

4. Glare is excessive contrast
Factors influence the degree of
discomfort glare :
• luminance of the glare source,
• the solid angle of the glare source,
• the background luminance
• the position of the glare source in the field
of view
Glare

5. Types of lighting
Based on the way of usage:
• Task lighting
• Accent lighting
• General lighting
Based on the source:
• Natural lighting
• Artificial lighting

6. Task lighting
• Task Lighting is mainly functional and is usually the most
concentrated, for purposes such as reading or inspection
of materials.
• reading poor-quality reproductions may require task
lighting levels up to 1500 lux (150 foot candles)

7. Accent Lighting
Accent lighting is mainly decorative,
intended to highlight pictures, plants, or
other elements of interior design or
landscaping.

8. General lighting
• sometimes referred to as ambient light
• is intended for general illumination of an area.
• general lighting for a parking lot may be as low
as 10-20 lux

9. Natural lighting
• From visible sky + reflection
• Depends on:
-time of day
-season
-atmospheric pollution
• Accompanied by radiant
heat

10. Suggestions for improving
daylight:
• Orientation: towards North
or South-provides uniform
illumination
• Removal of obstruction:
• Windows:
• Interior of the rooms:
ceilings should be white,
upper portions of wall-light
tinted and lower portions
should be darker
Lighting without windows: The Pantheon in
the 18th century, painted by Giovanni
Paolo Panini

11. Measurement of daylight
• In terms of a factor called DAYLIGHT FACTOR
“It is the ratio of illumination at a given point to
illumination at a point exposed simultaneously to
the whole hemisphere of sky (~500 foot candles)
excluding direct sunlight.”
D.F. =
Instantaneous illumination INDOORS___________
X 100
Simultaneouslyoccurring illumination OUTDOORS
Determined by Daylight Factor Meter

12. Artificial Lighting
System of lighting:
• Direct: 99-100% light projected towards working
area
• Semi-direct: 10-40% light is projected upwards,
reflected back by the ceiling on the object
• Indirect: 90-100% of light is projected towards
the ceiling and walls
• Semi-indirect: 60-90% light directed upwards
and rest downwards
• Direct-Indirect: light is distributed equally

13. Methods of artificial lighting
FILAMENT LAMPS
• The electric current
heats up the tungsten
filament and the light
emitted depends
upon the temperature.
FLUORESCNT LAMP
• A long straight tube
coated with phosphor
containing low
pressure mercury
vapor that produces
white light.
• Coated inside by a
fluorescent material
which absorbs UV
radiation and remit
the radiation in visible
range

14. Measurement
• Luminous
intensity
• Luminous flux
• Illuminance
• Luminance

15. Luminous Intensity
• Describes brightness of point source
• Measured in Candela
Luminous flux
• Flow of light related to a unit of solid angle
• Measured in lumen
Illumination
• Amount of light reaching a surface
• Measured in lux per unit area

16. Luminance
• measure of the density of luminous intensity
in a given direction.
• describes the amount of light that passes
through or is emitted from a particular area,
and falls within a given solid angle.
• The SI unit is candela per square meters
(cd/m2
).
Solid Angle:

18. Lighting Standards
“The illumination level should be 30 times higher
than the level at which the task can just be done”
Some recommended illuminations suggested by
IES (in lux):
• Reading-100
• General office work-400
• Fine assembly-900
• Watch making-2000-3000

19. Energy Consumption
• Artificial lighting consumes a significant part of
all electrical energy
• for some buildings over 90 percent of lighting
energy consumed can be an unnecessary
expense through over-illumination

20. Strategies Available To
Minimize Energy Consumption
• Specification of illumination
requirements for each given use area.
• Integration of space planning and
interior architecture
• Selection of fixture and lamp types that
reflect best available technology for
energy conservation
• Training of building occupants to use
lighting equipment in most efficient
manner
• Maintenance of lighting systems to
minimize energy wastage
• Load shedding
• Automated lighting control
• Day lighting

21. Health effects
• Radiation and UV Rays
• Therapeutic effect in premature infants with
hyperbilirubinemia
• Activation of precursors of vit. D
• Headache frequency, stress, and increased blood
pressure-higher lighting levels.
• Glare or excess light-decrease worker efficiency.
• designing lighting systems that maximize the right
amount of light at the appropriate time of day for the
elderly may help relieve symptoms of Alzheimer's
Disease
• Circadian disruption may lead to numerous health
problems including breast cancer, seasonal affective
disorder, delayed sleep phase syndrome, and other
ailments

22. Light Pollution
• Light pollution is described as artificial light that
is excessive or intrudes where it is not required
• a growing problem in reaction to excess light
being given off by numerous signs, houses, and
buildings
• unnecessary energy costs and carbon dioxide
emissions