Lighting

Good quality lighting is a necessity for all areas of human activity: This is obvious in the commercial sector as well as in offices, which need good lighting.

However, the craft and industrial sectors also have their own requirements when it comes to ensuring working conditions that offer safety, visual comfort and profitability.

 

1. Selecting the right type of lighting
 

Level of lighting required
 

National workplace safety and compliance standards set out the minimum lighting levels that must be provided. In Luxembourg, it is standard condition ITM CL.55-2 www.itm.lu that imposes the minimum illumination level.

Ensuring sufficient lighting and lighting quality is one mean of preventing accidents at work; it also has an impact on productivity and staff motivation.


Energy efficiency of lamps


The efficiency of light sources is expressed in Lumens per Watt (Lm/W). In other words, the higher the energy efficiency, the more economical the installation, for a given level of lighting.


Quality of emitted light


Different light sources can create different perceptions of the environment at the same lighting level:

The colour rendering index (CRI) measures the ability of a light source to accurately reproduce the colour of illuminated objects:

  • 100% equals natural light, the best rendering possible
  • 80% is a good value
  • CRI below 80% degrades colour perception

The colour temperature describes the shade of light emitted: from "warm white" (similar to an incandescent bulb) to "daylight" (bluish shade).

 

Type of light fittings
 

When it comes to choosing new light fittings, functional and aesthetic aspects are often given priority over energy efficiency. However, the choice of light fitting has an impact on energy efficiency owing to:

  • the mode of lighting: direct or indirect
  • the directionality of the light beam on the surfaces or objects to be lit
  • the efficiency of the light fitting is provided by the manufacturer. Keeping old fittings or letting them get dirty affects the overall performance of lighting systems
  • the type of ballast for fluorescent lighting; this is also important: older types of electromagnetic ballasts are much less economical than modern electronic ballasts.


Architectural characteristics of the building
 

  • The shape of rooms and the height of the ceiling have an impact on the luminous flux reaching users
  • The presence of walls, bulky equipment or stored goods can block the light
  • Too dark a wall colour can cause significant loss of light
  • The possibility of benefiting from free, high-quality natural light is of course highly desirable

 

2. Choice of lamps


LED lamps

 


 

 

Efficiency: up to 100 lm/Watt

Colour rendering: CRI = …85 (good)

Lifetime: up to 50,000 hours

Applications:
Replacement of almost all old types of lamps: incandescent, mercury vapour, "TL" tubes, including high power for large halls or outdoor use.
It's an excellent choice: their energy efficiency is high, and they benefit from a very long life, which offers an advantage in terms of maintenance costs.
However, LEDs are not suitable for very hot environments such as cooking workshops, the plastics industry, foundries, etc. LEDs offer an ecological advantage: they do not contain mercury, unlike compact fluorescent lamps and TL tubes.
Dimming is usually possible.

 

Fluorescent tubes

 

 

Efficiency: up to 114 lm/watt (T5)

Colour rendering: CRI = 64…90 (good)

Lifetime: up to 24,000 hours

Applications:
All types of buildings of moderate height.
T5 lighting is the most energy efficient under standard operating conditions; T12 lighting is reserved for low-temperature applications.
There are many variations of light colour and the colour rendering index.
The use of a high quality electronic ballast is recommended in order to guarantee good energy efficiency and a long life for the TL tube.

 

Discharge lamps (metal halide)

 

 

 

 

Efficiency: 85 to 118 lm/watt

Colour rendering: CRI >90 (very good)

Lifetime: 9,000 to 15,000 hours

Applications:
Quality lighting of halls with high ceilings: manufacturing halls, sports halls, commercial premises, etc.
They combine essential qualities: energy efficiency, colour rendering and lifetime.

 

Sodium lamps

 


 

 

 

Efficiency: 72 to 150 lm/watt

Colour rendering: CRI < 25 (poor)

Lifetime: 14,000 to 30,000 hours

Applications:
Lighting for roads, industry and horticulture.
High energy efficiency and their long lifetime.
Low pressure sodium lights are very durable and extremely efficient (180 lm/Watt).
They are used for road lighting.
These lamps provide a characteristic yellow-orange light (CRI = 0).

 

3. Potential improvements


Behavioural aspects
 

  • Remind staff to turn off the lights in the premises as soon as it is unoccupied
  • Reduce the use of lighting when the building is not in use (except for safety-related provisions such as emergency exit signs)
  • Only switch on the lighting for occupied workstations
  • Make maximum use of the potential of natural, free, high-quality light


Replacement of old lamps


Considering that old incandescent lamps can cost up to 10 times their purchase price in energy costs, exchanging these old lamps for more energy-efficient lighting is often a cost-effective operation.

Carefully select new lighting according to your needs (level of light, quality of light, lifetime) and also replace less efficient light fittings where possible.


How to reduce energy consumption by up to 80% with TL tubes?


Improvement actions and estimated energy conservation in percentages

Improvement actions

Estimated savings 

Replace old T8 tube light fittings with modern light fittings, equipped with efficient reflectors and T5 tubes

approx. 30%

Use quality electronic ballasts, which can reduce operating losses, greatly increase tube lifetime and improve visual comfort

approx. 20%

Use ballasts with "cut-off" technology that cuts off power to the preheating filament once the tube is lit

approx. 10%

Time-of-use control by motion sensors in passageways, light intensity control by dimming the lights

approx. 20%

 

Lighting maintenance


Replace light fittings regularly and in good time. With TL and CFL lamps, the light output decreases with the number of operating hours: the required level of illumination can no longer be guaranteed beyond the nominal lifetime. A well-designed renewal campaign will restore nominal brightness or bring the lighting up to standard in an orderly fashion.

It is also advisable to clean the light fittings on a regular basis if they are located in a dirty environment.