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