ergonomical illumination in real world
Post on 06-Dec-2014
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ILLUMINATIONA Special Thanks for the sake of Contributions from
AJAY K
DWARAGANATH P
GOWTHAM M
What is Illumination?Lighting or illumination is the deliberate use of light
to achieve a practical or aesthetic effect. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight.
Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.
What is the significance of good lighting?
Office work is visually demanding and requires good lighting for maximum comfort and productivity. "Good" lighting means providing enough illumination so that people can see printed, handwritten or displayed documents clearly but are not blinded by excessively high light levels (a cause of glare).
What are signs of poor lighting?
The most common complaints resulting from poor lighting are:
· difficulty seeing document or screen (too much light or glare, or too little light or shadows),
· eyestrain,
· eye irritation,
· blurred vision,
· dry burning eyes, and headaches.
Parameters of illumination
Characteristics of Lighting Systems
❖ Equivalent Spherical Illumination: Measures the effectiveness of lighting systems.
❖ Visual Comfort Probability:
Is a direct-brightness ratio.
❖ Task Illumination:
Measures the quantity of light at the work surface.
Factors that are important in creating 'better workplace lighting'
Vision factors- Contrast - or reflectance difference - between a task and its background
- Intensity range and control of light source
- Spectrum of light source and resulting color rendering effect
- Direction of light source
Comfort factors- Contrast between the task area and the general room view
- Control of glare in either task or general view
- The lightness of the space
- The luminous texture of the space
- Spectrum of the light sources
- Direction of the light sources
- The perception of controlling intensity - through dimming or switching
Types of Lighting System
Direct Lighting
* 90-100 percent of the illumination is directed downward to work surface
* Creates glares, reflections, and shadows
Semidirect Lighting 60-90 percent of light is directed down-ward,
with remainder directed upward and then reflected back downward.
Shadows are less of a problem with direct lighting systems.
Indirect Lighting
* 90-100 percent of light is directed upward,which then is diffused and is reflected downward.
* Eliminates most shadows and glares.
* This system is recommended for most types of offices.
Semi-indirect Lighting* 60-90 percent of the light is directed
up-ward and then reflected downward
* Remainder of light is directed downward
* Shadows and glare are more problematic than with indirect lighting.
General Diffuse
* 40-60 percent of light is directed to work surface with remainder reflected down-ward.
* Shadows and glare are more noticeable than with semi-indirect.
Interior lightingGeneral lighting
General lighting provides uniform illumination over the whole working area and does not limit positioning of the work
*
Localised lighting
* Localised lighting provides different levels of illumination in different parts of the same working area.
* It matches the level of illumination to the needs of specific tasks
Local lighting
Local lighting is usually a combination of background lighting and a luminaire close to the actual work area
Exterior lightingIn general all exterior installations should:
• achieve a reasonably uniform
illuminance on all relevant work areas;
• avoid glare to the users of those
areas and to occupants of nearby areas.
Different types of light fixtures
Direct light fixtures project 90 to 100 percent of their light downward toward the work area. Direct lighting tends to create shadows.
Direct-indirect light fixtures distribute light equally upward and downward. They reflect light off the ceiling and other room surfaces. Little light is emitted horizontally meaning direct glare is often reduced. They are usually used in "clean" manufacturing areas.
Different types of light fixtures
Indirect light fixtures distribute 90 to 100 percent of the light upward. The ceiling and upper walls must be clean and highly reflective to allow the light to reach the work area. They provide the most even illumination of all the types of fixtures and the least direct glare. Indirect light fixtures are usually used in offices.
• Shielded light fixtures use diffusers, lenses and louvers to cover bulbs from direct view; therefore, helping to prevent glare and distribute light.
• Diffusers are translucent or semi-transparent (see-through) covers made usually of glass or plastic. They are used on the bottom or sides of light fixtures to control brightness.
• Lenses are clear or transparent glass, or plastic covers. The lens design incorporates prisms and flutes to distribute light in specific ways.
• Louvers are baffles that shield the bulb from view and reflect light. The baffles can be contoured to control light and decrease brightness. Parabolic louvers are specially shaped grids that concentrate and distribute light.
Different types of light fixtures
General Lighting Focal Point
Ceiling Height Distance from
(H) Wall (D)
8 Feet 24 inches
10 Feet 36 inches
12 Feet 48 inches
YES NO
Ergonomic and Non-Ergonomic Lighting position
Lamp type Angle for
exclusion zone• Tubular fluorescent 10 degrees
lamps
• Discharge lamps 20 degrees
with a fluorescent
coating
• Discharge and 30 degrees
incandescent lamps
which allow a direct
view of the arc tube
or the filament
Angular exclusion zone
Line of sight
What are some of the most common lighting problems?
Poor lighting can cause several problems such as:* Insufficient light - not enough (too little) light for the need.*Glare - too much light for the need.* Improper contrast (based on glare).*Poorly distributed light.*Flicker.
GLARE
● Glare is more when mounting height of the light is lowered, since the lighting unit approaches horizontal line of sight
Lighting unit close to horizontal line of sight
Lighting unit away from horizontal line of sight
Glare is more Glare is comparatively less
● Glare is worse in large rooms since the lighting unit from far off the room slides towards the horizontal line of sight
GLARE
Disability glare from a light fitting
Distracting reflection close to the line of sight
The reflection of a window is masking information on the screen
● In case of fluorescent lighting, light emitting from side panes produces glare. Hence broad-on side view will have more glare. But in end-on view the apparant area of bright side panels is diminished and so glare is reduce
Broad-on side view End-on side view
GLARE
Suitable Lighting positions
Activity Typical locations/ Average Minimum
types of work illluminance measured
(lux) lx illuminance (lux) lx
• Movement of people, Lorry park, corridors, 20 5
machines and vehicles circulation routes
• Movement of people, Construction site 50 20
machines and vehicles clearance, excavation
in hazardous areas; and soil work, loading
rough work not bays, bottling and
requiring any perception of detail canning plants
• Work requiring limited Kitchens, factories 100 50
perception of detail assembling large
components, potteries
• Work requiring Offices, sheet metal 200 100
perception of detail work, bookbinding
• Work requiring Drawing offices, factories 500 200
perception detail of fine assembling electronic
components, textile production
Reflectance Value of Color
❖ Various colors possess different reflectance values.
❖ Lighter colors tend to reflect a greater percentage of light than do darker colors.
❖ Among the lighter colors cool colors create calm and retiring mood and warm colors create warm and cheerful mood.
• Cool colors create calm and retiring moods.
• Warm colors create warm and cheerful moods
• Gray has a sleep-inducing effect.
Colors tend to create
different moods
Impact of Color
THANK YOU
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