Office Lighting System
The primary component of office environment is lighting. Every nature of work involves seeing and reading in an office. Hence, there is a need of adequate lighting system in office.
Inadequate lighting results in delays and mistakes. Poor lighting requires longer time to read and visual image is vague. Besides, poor lighting causes eyestrain, mental fatigue and irritation to the employees. On the other hand, good lighting is not only avoiding delays and mistakes but also improves the motivation and morale of employees.
Office lighting should make possible more than more seeing, it should make it possible for the worker to see what he is doing – clearly, quickly and accurately, Sometimes, over lighting is also responsible for over strain and headache to workers.
Characteristics of Good Lighting System
Adequate or good lighting system must possess certain well defined characteristics which are discussed below.
1. Sufficient Quality
Foot candle is the unit measurement of light. Generally, between 50 and 60 foot candles light is recommended for office work.
2. Sufficient Quantity
Number of lights is based on the number of employees working in an office. The area of an office is taken into consideration to provide sufficient quantity of lights. Approximately one watt per square foot of area provides 15 foot candles.
Brightness of light means the light reflected from an object. It also controls contrast which affects seeing. The great contrast prevents seeing.
The lighting system should provide the right degree of intensity. The light should be well spread over the workplace and should not cast shadows. The spreading of light should be uniform over the entire work surface.
The Illumination Engineering Society, New York has recommended the following intensity values of light in relation to the different types of office work.
Good lighting system should not cause any glare on surface. Direct glare results from sunlight or ceiling light. The use of shadows or light mixtures prevent direct glare. Light striking shiny or highly polished surface causes reflected glare. The reflected glare can be prevented by using such lighting system in which light does not strike such surface.
6. No contrasts
Abrupt contrasts in lighting of work surface and the remaining area should be avoided.
7. Right Diffusion
Lighting should be well diffused over the work place. Proper attention is to be devoted for avoiding casting any shadows. Use of proper fixtures and multiple sources helps in proper diffusion of light.
Types of Office Lighting System
The lighting system consists of the following five types
1. Direct Lighting
Approximately 90% to 100% of the light is directed downward to the working surface in this type of lighting. This system uses some shade or reflector for the source of light. It provides a good intensity of light. At the same time, it casts dark shadows around and raises a,direct and reflected glare that could cause eyestrain to the office employees.
2. Indirect Lighting
In this system, 90% to 100% of the light is directed towards the ceiling or walls and then the directed light is diffused and reflected on the work surface. This type of lighting system is soft and avoids shadows and glares and does not cause eyestrain. This type of lighting system is highly useful for general illumination but not for office work.
3. Semi-Direct Lighting
In this type of lighting, a transparent or translucent shade is used which directs 60% to 80% of the light downward. The remaining light is directed upward and the directed light is reflected from the ceiling. This lighting system is an improvement of direct lighting. So, dark shadows on the ceiling and glare are eliminated in this system.
4. Semi-Indirect Lighting
A transparent or translucent shade, bowl, cover or reflector is placed under the lamp in this lighting system. In this way, 20% to 40% of the light may be directly diffused downward on the working surface. The remaining 60% to 80% of the light may be directly towards the ceiling and walls.
Such directed lighting is reflected downward to the working surface. This form of lighting is intermediate between direct lighting and indirect lighting.
5. General Diffuse Lighting
An equal amount of light is diffused directly and indirectly by its reflection from ceiling and walls in this type of lighting system. This system gives more light with the same wattage than the semi-indirect lighting system does.
Kinds of Lighting for Office
There are two sources of light, namely, the sun and the electricity. Natural light is derived from the sun. The artificial light is derived from the electricity. Therefore, there are two types of lighting i,e. natural lighting and artificial lighting.
1. Natural Lighting
Natural light or day light is the best form of lighting. It is advisable and less expensive to use natural light at the maximum. Windows should be large and high up. The use of natural light protects the health and efficiency of employees.
The proper provision should be made to prevent direct sun light falling upon the working surface. The office layout should be so planned that the light falls upon the left shoulders or right shoulders of left handed employees. Dark coloured curtains, green or dark window shades.
Venetians and blinds are used to control the glare during the bright days or during bright hours of the day. In normal working positions, the employees should not allow to face windows.
2. Artificial Lighting
Natural light is not fully dependable and adequate. The artificial light is used to supplement natural light. Artificial lighting helps to provide adequate light on the working surface. Great developments have taken place in artificial lighting over the last 75 years. From gaslight, science has progressed to carbon filament electric lamps, tungsten and fluorescent lamps.
The primary advantage of artificial lighting is that it can be easily controlled as in the form of quantity, quality and intensity.
Artificial lighting is of two types.
I. Fluorescent Lighting
The illumination produced by fluorescent lighting is closely resembled with natural lighting. This type of lighting system involves heavy expenses to install. Even distribution of light on the working surface, less heat, less glare, consume less electricity and longer life are the characteristics of fluorescent lighting. Many office buildings have been constructed with luminous ceilings to eliminate shadows and glare on working surface.
II. Incandescent Lighting.
This type of lighting system involves the use of filament bulbs. The installation of incandescent lighting is much less expensive than fluorescent lighting. Generally, incandescent lighting is not preferable by anybody. The reason is that incandescent lighting has many inconveniences. They are less natural colours, less life bulbs, consumes more electricity, more glare and shadows. Therefore, incandescent lighting is used in residential houses and small offices at the maximum.