It is not a secret that illumination affects the workers’ health and productivity. Thus planners and owners of production areas aim to create the comfortable lighting for their employees. It is not only about job safety but also an important issue of enterprise economics.
This article tells about all the things you should keep in mind when creating the illumination that would be both comfortable and energy efficient.
The way the light influences health and working process may not be so evident. But still there are some important aspects it can affect:
80% of information is received visually. We constantly “scan” the world around us determining shapes, colors and distances.And it’s about good or bad lighting that makes this information more or less precise and easy to perceive.
Light color and intensity can make the worker feel sleepy or awake. Incorrect illumination can cause lassitude and headaches. Long exposure can become a reason of major health problems. The vision problems caused by poor workplace illumination is a widespread problem nowadays.
Vast number of industrial accidents happen because of poor illumination or the mistakes caused by inability to examine a certain object or to evaluate the risk.
This it is important to create a good collaboration between designers, engineers and ergonomists when planning the production area. It will help to avoid the mistakes that are almost impossible to fix later.
There is a number of official documents that should be considered when planning a workplace. It is CEN/TC 169 in EU and Arab Unified Building Codes in the Arab League.
Each region has its own specifics but they all include the same requirements:
sufficient objects contract
suitable color temperature
absence of stroboscopic effect
Workplace lighting should combine direct and diffused rays. Shadows shouldn’t be heavy and the light itself shouldn’t be dazing. Try to avoid the reflections and glares because they impede to determine the objects shape and location.
Lighting equipment should be easily accessible for cleaning, maintenance and replacement.
You also should keep in mind that the lamp’s luminous flux may change with its lifetime. Incandescent light bulbs preserve it during the whole service time, which is usually short. Fluorescent and LED bulbs may lose 25-30% of initial brightness. The difference is the time when it happens, CFLs start to dim after 1 000-10 000 working hours and LEDs can last up to 60 000 hours.
Illumination intensity is measured by a luxometer (the device converts the light energy into electrical signal) and is indicated in lux. The lowest level of intensity depends on performed visual task.
Visual tasks can be divided into 3 categories:
Tasks without optical devices use(microscopes, magnifiers etc.) – object may be located at any distance
Tasks with optical devices use – objects cannot be sufficiently examined even under the bright lighting.
Tasks that demand perceiving data from screens
To determine the necessary luminance should be taken into consideration:
object size (on the distance less than 0,5 m) – minimal size of object or its details to be examined
object / surrounding contrast – correlation of their brightness. Can be calculated using the formula:
if K<0,5 object and surrounding have a significant brightness ratio. They can be easily perceived.
background lightness – the surface behind the object. It is defined by ρ – surface reflectance factor. Background is light if ρ > 0,4, medium – if ρ is from 0,2 to 0,4, dark – if ρ < 0,2.
Small size and low contrast impede the object perception. It is also more difficult to discern even the big objects if they are on a long distance and the lighting is poor. The more difficult is the perception the better illumination should be in the room.
Each official document sets its own requirements to lighting equipment. Here are the rules from European CEN/TC standards.
Besides the task type, it is good to keep in mind the object and its surrounding reflectance, differences between the artificial and natural lighting of the room, worker’s age, etc.
Even at the same illumination level objects may be perceived in a different manner. It depends on object itself and its surrounding. There are main factors that determine the visibility.
Our vision is good at determining object / background or object/its parts brightness ratio. The contrast depends on reflectance factor, shadow heaviness and colors of object and its surrounding.
These two factors allow determining the arrangement of the work station, classifying different zones according to visual response. Their difference is derived from worker’s position, ease of interaction and visual perception plenitude.
It depends on whether the object and the observer are moving. The ability of worker’s eyesight to adapt to external factors is also important.
Glare is the temporary incapacity to discern things. It can cause vision problems, functional and psychic disorders.
Glare can be:
Direct – when looking at the light source itself
Reflected – caused by high reflectance surfaces located in the visual zone
Glare can be caused by the following factors:
The highest brightness an eye can stand is 7,500 cd/m2. Below you can see the brightness of the most widespread light sources.
Sources located within a 45-degree angle of the observer’s line of sight are the most dangerous. The best solution is to get rid of them at all.
The greater is the brightness of object and its background, the greater is the glare. Eye won’t be able to accommodate to such conditions. Brightness disparities should not be higher than the following:
object—work surface: 3:1
Even the dim light can cause glare if you look long enough on its source.
Pay special attention to light distribution and brightness contrast. Good distribution can be achieved by replacing localized illumination by general. And the lighting equipment should be equispaced around the room to reduce brightness gaps.
You can also install diffusors and reflectors to direct the light to the right side. But the excessively scattered light is also bad for spatial perception.
There is no lighting more comfortable than the natural one. But it has a major disadvantage of being dependent on time of the day, season and weather. Natural illumination is unstable and should be amplified by the artificial.
There are 3 popular artificial illumination systems:
Light equipment is equally spread regardless of workplaces positions. It is usually used for nonstationary tasks.
Anti-glare devices (grilles, reflectors, etc.);
A fraction of the light should be distributed toward the ceiling and the top of the wall;
lamps should be installed as high as possible in order to minimize the glare and to create the uniform illumination.
The general illumination is supported by the workplace lamps. In order to reduce the glare you should install the reflectors which will cover the light source. This scheme is the best solution for high-precision tasks.
Ceiling lamps are situated according to their technical characteristics and light requirements of each workplace. It suits the best for places where the good illumination is a priority.
Lighting color influences the work performance and the health the same way the brightness and contrast do. Nevertheless, it is more individual, so it is difficult to set the strict rules.
Colors can be divided into 3 groups:
warm: yellow, red, orange – suitable for residential use
neutral: white daylight – suitable for offices and working areas.
cold: bluish – suitable for labs and other areas where the clean and cool ambience is required.
You can read more about influence of light color in the article Hot & Cold.
Light perception is also affected by the environment: colors, locations, textures and furniture.
Follow this rules and you will enhance the light efficiency:
Perfect color for ceiling is white with reflectance factor (ρ) not below 75 %. It helps to create the diffused illumination, reduce the glare from other objects and cut the amount of lamps needed.
Avoid the glossy paint because of its high reflectance and glare danger. Choose pale matte paint with ρ = 50 - 75 %.
Floor should be of darker colors. ρ - between 20 and 25 %.
Workplaces, equipment and tables should have ρ = 20 - 40 %. It is better to cover equipment with non-glossy paint of gray or light-brown color.
All of these rules impose too many restrictions and difficulties when designing a workplace area. It is much easier to use the light bulbs whose health safety is guaranteed by the manufacturer. LED lamps Jooby are among them. We took into account all the necessary requirements to make their light comfortable. With Jooby lamps you won’t need to study all the construction official documents to make the good illumination. Jooby will grant the harmony of light wherever you use them.