In the ILO manual, improving working conditions and productivity in the garment industry, it is highlighted that improved lighting in factories have led to as much as 10 per cent productivity improvement with around 30 per cent reduction in errors.
Areas in garment factory where lighting is most important
Appropriate lighting is the need for every department, irrespective to the task being handled. Although, there are some areas where focus on maintaining proper illumination is very crucial in a garment factory, like the inspection points (on-floor and in stores), sampling, and the finishing section, as these areas are crucial to the quality of the production. The tasks involved in these areas require high levels of worker focus and accurate lighting ensures lower errors and defects passing on to the next stage. Apart from that, proper task lighting at every production workstation is also necessary to ensure required luminosity.
Illumination- Codes & Standards
The main factors which contribute to “quality of lighting are brightness and brightness control, directional qualities, colour, colour contrast and colour rendering (Hewitt n.d., pp.9-10) (N. Ahmed 1992).
The following table illustrates the recommended Illumination and Glare Index that are applicable to various task families in garment factories (below table): Lighting standards and codes usually provide recommended illuminance ratios between the task area and its surroundings (EN 12464-1 2002) (CIBSE 1997) (IESNA 2000, 676708).
General lighting installations typically provide an approximately uniform illuminance over the whole of the working plane. Such systems are often based upon the lumen method of design, where an average illuminance is:
In many workplaces it is unnecessary to illuminate all areas to the same level. Localised or local lighting may provide some degree of energy saving, but whichever system is used the variance in illuminance across an interior must not be excessive. The diversity of illuminance is expressed as:
Layout should be based on “Spacing to Height Ratio? (SHR) close to the maximum spacing to mounting height ratio at which this uniformity is achieved.
As a rule of thumb, to achieve uniform lighting requires the spacing between the luminaries to be no larger than 1.5 times the mounting height.
Luminaire Spacing = 1.5 × Hm
The ‘Spacing to Height Ratio’ (SHR or S/H) is the ratio of the centre-to-centre distance between adjacent luminaires, to their height above the working plane. It is used to estimate if lighting is uniform. For a rectangular arrangement of luminaires:
SHR =(1/H )v(A/N)
A = total floor area, N = number of luminaires
This enables the most economical lighting installation to be planned. In practice, the spacing may be closer to avoid shadowing or to increase the illumination.
Types of lights
Lighting in a garment factory can be classified into three major categories, accent lighting, task lighting and general lighting.
Accent Lighting: The decorative lighting used to highlight the interior design or landscaping features in the factory. These are mainly used in office and reception areas.
Task lighting: These types of lights are used when the focus of the light needs to be on particular task, for instance, needle light on a sewing machine.
General Lighting: This consists of the ambient lighting in the factory that used on the walls and ceiling to illuminate the area.
Measuring light intensity using a Lux Meter
Measuring the amount of light on the factory floor is very important since natural lighting alone is sometimes inadequate to properly illuminate most of the work on the floor. Lux meters ensure that the light levels fall within a certain level where it is bright enough but not too bright to cause glare. In fact, lux meters can be used to enhance productivity because having the correct level of lighting means that workers experience less fatigue and consequently, higher efficiency.
A standard lux meter is ideal for use in areas that utilise incandescent lighting. They can also be used for fluorescent lighting areas but are subject to a small error in measurement. This makes them ideal tools for checking lighting in most workplace environments.
Improving lighting in the factory
Improvement of the lighting in your workplace does not necessarily mean huge investment. It can also be done by better usage of existing lights, keeping them clean and in good condition, ensuring correct position depending on the tasks’ demand, and making better use of your factory layout to benefit from natural light.
Effects of good quality lighting
- Even distribution of lighting over the whole task area
- Lighting without flickering and glare
- Appropriate light colour
- Sufficient light at the visual task
There are some simple rules that should be followed to ensure proper lighting, like making use of day light in the factory (ensuring the glare is controlled), choice of appropriate visual backgrounds, choosing the best source for lighting to avoid glare, using proper lighting devices and fixtures and avoiding any shadows on the task, and obviously ensuring regular cleaning and maintenance of the lights sources and windows in the factory.
Maintenance of lighting is a great practice to keep the lighting systems working at peak performances. Neglecting lighting maintenance can undo all the performance of a good lighting system.
- Cleaning: Keeping the lights and fixtures clean may be the most important factor in keeping their performance high. However, it is often neglected. Along with the lights, the wall and ceiling surfaces should be also kept clean so that they reflect the light properly for better illumination.
- Replacement: Bulbs and tubelights should be replaced not only when they break, but also when their brightness decreases down from their normal level. Faulty or less bright lights can collectively cause a bad effect in the illumination of the factory floor.
- Developing a lighting maintenance programme: A lighting maintenance programme can greatly help in the routine check-up of lighting and illuminance on the factory floor. An organisation should work closely with the electrical contractor and start the evaluation of the existing lighting system. The electrical contracting firm should develop lighting fixtures based on different processes and space usage.