Lighting Modernization

In many commercially used buildings such as office buildings, hospitals, halls or even shopping centres, old, tubular fluorescent lamps (T8: 8/8-inch or 26 mm diameter) are still in use. It is not uncommon for these lighting systems to be 20 or even 30 years old and no longer meet today's requirements and should be replaced or modernised.

Modern lighting today is usually based on LED technology. The modern fluorescent lamps (T5: 5/8-inch or 16 mm) are also widespread and, installed in the right place, meet demands for aesthetics and sustainability.

Acceptance

Constantly changing lighting conditions are poorly accepted. However, everyone has already become accustomed to the fact that the light comes on automatically when entering a room or a corridor and goes off again when leaving. This is practical and expedient.

If luminaires are converted, a declaration of conformity must be requested from the supplier or manufacturer.

Today, the automation of lighting is easily possible by means of motion and presence sensors. In addition, thresholds, sensitivities and times can be configured on the sensors, making them adaptable and versatile.

Nevertheless, the fundamental question arises: what is the right light setting? It has been shown that complete automation, for example in corridors and stairwells, makes perfect sense. Here, individual requirements are certainly secondary. In the workplaces, semi-automatic systems have proven themselves well.

The user or users themselves decide when the light is switched on. By means of presence sensors, the light is then operated as long as someone is in the corresponding area, or someone simply switches it off again. In terms of a threshold value, such a lighting system may well be on once when it shouldn't be. In return, it is also sometimes not on, simply because no one has pressed the switch.

Cost items

In the commercial sector, in addition to acceptance, the economic aspects of lighting are of course also important. This is not primarily about the acquisition costs of the new lighting, but about the annual operating costs. In addition to the acquisition costs, these include costs for installation and adjustments, the energy consumed, interest (amortisation) and maintenance.

The replacement of an aging lighting system in particular must be carefully planned. In particular, it must be decided whether only the lamps (light sources) or the luminaires as a whole are to be replaced. With the replacement of lamps, adaptation costs can often be saved. Modern lamps (T5, LED) produce more light, so the number of luminaires can be reduced and the positions changed. This can lead to painting and other touch-up work. Further, the low-voltage installation standard (NIN 2015) must be observed. If the lighting is replaced, the new one must be installed in accordance with NIN 2015. It may be necessary to retrofit obsolete switchgear, for example with residual current devices (RCDs), if there are also sockets in the lighting group. This can be very expensive.

If luminaires are converted, a declaration of conformity must be requested from the supplier or manufacturer. In older buildings, lighting systems may be protected (heritage protection, monument protection). In such cases, the only option is to replace the lamps or install additional lighting points.

The energy costs can be easily estimated via the installed power and the full load hours. In comparison with an old lighting system, the savings can also be quantified in this way.

In SIA 380/4, the illuminance, the specific power and typical values for the full load hours can be found depending on the room use. However, it is better to make a good estimate of the full load hours of the premises concerned and to include these values in the calculation.

Because the efficiency of LED lamps has improved very rapidly in recent years, it is now possible to meet the illuminance specifications and at the same time even undercut the target values for specific power. These target values were still based on energy-saving lamps.

In terms of maintenance, it is mainly the replacement of defective lamps and the associated costs that have an impact. In larger companies, the replacement of a defective lamp is estimated to take 30 minutes. In companies with hundreds or thousands of lamps, this effort can be considerable.

The average service life of the lamps is therefore a very important planning parameter. Especially with energy-saving lamps, experience has shown that the expected operating hours have not been achieved and they have to be replaced much more frequently than planned. The reason for this is not only the poor quality of the lamps or the ballasts, but also the local heat generation, which stresses and damages the ballasts.

LED or T5?

Today, contemporary, efficient lighting is realised with LEDs or the latest generation of T5 fluorescent lamps. Both light sources achieve an efficiency of approx. 100 lumens/watt. The service life of about 50,000 hours for LEDs and 25,000 hours for T5 fluorescent lamps allow for several years of low-maintenance operation. The main difference between the two illuminants is the way in which the light is distributed.

While the LED is a point source and has a direct light emission, the fluorescent tube with diffuse light emission can illuminate the entire room. It is precisely this characteristic that is often advantageous in rooms with lower aesthetic demands and dark ceilings. Fluorescent lamps with appropriate reflectors can direct a certain proportion of the light indirectly to the ceiling, which leads to a brightening of the ceiling. From there, the light spreads further into the rest of the room. Since the LED emits the light in one direction, this indirect effect cannot simply be transferred. If this effect is to be achieved with LEDs, additional LEDs must be present in or on the luminaire. Both solutions can work well. Ultimately, aesthetic and economic factors are decisive.

New lighting systems should provide the right amount of light in the right place, not too little and not too much, and at the same time be energy-efficient. Particularly in large rooms, a division into two or more lighting zones is therefore often useful. Transit areas and workplaces in large rooms are supplied with different amounts of light.

Good systems today achieve values of 80 lumens/watt and more. These values should be specified and also checked for good planning.

For efficiency, the lux specifications are to be achieved with as few installed watts/m2 as possible. For the installed lighting system, this means having the best possible system value in lumens/watt.

Good systems today achieve values of 80 lumens/watt and more. These values should be specified and also checked for good planning.

In order not to "optimise oneself into a dead end" by maximising efficiency, the systems can be equipped with adaptable components. For fluorescent lamps, multiwatt ballasts have proven their worth, allowing the use of lamps with different wattages. LED systems with the possibility of adjusting the operating current offer the same flexibility.

Despite the long lifetimes, every light source must be replaced at some point. LED and T5 fluorescent lamps have the property of decreasing in luminosity over time. A replaced, new lamp therefore shines a little brighter. Technically this is completely unproblematic, but it can be unaesthetic. Lamps with frosted glass can partly conceal this effect. In the case of LED lamps, the situation is aggravated by the fact that LED modules can differ in light colour, which is perceived by the eye.

After all, LEDs are constantly being developed further. The modules that are installed in lamps today will probably no longer be available for purchase in five or ten years. However, there are manufacturers who offer certain guarantees. Because of the aforementioned properties and technical progress, however, it also makes no sense to stockpile.