Fluorescent lamps have been present in production halls and office spaces for many years. Over time, however, the technology has changed and conventional fluorescent lamps have been replaced by modern, more energy-efficient LED fluorescent lamps, also called LED tubes. Therefore, it seems that replacing them can prove to be very beneficial for the client in terms of both savings and quality of light. However, there’s another solution available: a dedicated LED luminaire, a more expensive choice, but probably definitely more beneficial. Let’s see!
Cheap replacement of conventional fluorescent lamps with LED tubes
The differences in the production technology of lamps are very large and significant not only when their lifespan and efficiency are concerned, but also when we take a look at the fixtures they are mounted in. Traditional fluorescent lamps use phosphor fluorescence caused by a discharge in the gas mixed with mercury. Such a design requires using a dedicated power supply system called an electronic ballast. An alternative to traditional fluorescent lamps are LED tubes made of plastic (less often – glass) that have a different power supply system, as well as different design and construction. In addition, fluorescent lamps mounted several years ago use fluorescent sources and not LEDs. These types of lamps were characterized by an omnidirectional light and a relatively low surface luminance. In LED tubes, however, the light is distributed in one direction with smaller emission angles, so the luminance values are higher with the same luminous flux values and dimensions.
In modern LED tubes, the electronics responsible for the power supply are located at their ends – exactly where a filament was located in traditional ones. This means that the lighting area is shorter, which helps to increase the luminance. When a traditional fluorescent lamp is replaced with a LED one dedicated to work with the existing fluorescent ballast, there’s no need to interfere with the installation, so the assembling costs are lower. This is the cheapest option possible; however, it’s not flawless.
Reduced effectiveness and efficiency
When deciding to replace fluorescent lamps with LED tubes, we must be aware that in the case of old, long-used fixtures, changing only the light source will not bring us great savings, . because of technical condition of fixtures: they may be dirty, with a degraded quality of materials and tarnish on the shades. One of the reasons is that many such low IP luminaires have an open design, so they are not protected against external factors in any way. In the case of sealed luminaires with higher IP, degradation in the quality of materials may be caused by the light of the cheap fluorescent lamps itself. The combination of these effects may lead to a situation in which we lose about 30-40% of the efficiency.
In addition, LED tubes may not be compatible with the existing reflector in the luminaire, which may cause a change in the light quality and further reduction of its efficiency. In total, in case of such replacement of traditional fluorescent lamps with LED tubes, we may lose even more than 50% of the light quality. This applies to the traditional lamps with a ballast (fluorescent lamps with an electronic system). There is an alternative solution, though, for tubes using directly the line voltage. However, this requires modifications to the luminaire’s power supply system but helps to reduce potential losses by approximately 10%.
However, another problem may arise here. All changes in the design deprive the luminaire of compliance with the CE declaration and safety certificates it had originally, because of the changes that are made in the electrical connections. Incorrectly performed changes may cause a risk of electric shock or short circuit in the installation. In the worst case, in the event of a fire resulting from a short circuit in such a luminaire, people responsible for electrical changes may face serious criminal liability, while the insurance company may refuse to pay the compensation.
50% lower efficiency
In total, the conversion losses to LED tubes lamps can exceed even 50%!
LED luminaires – not only better efficiency
Most of the customers are interested in the expected return of investment time when replacing the lighting system. LED tubes have a luminous efficacy of 120-140 lm/W, and the higher-quality ones – even up to 180 lm/W. Given the possible losses of 50%, we may achieve 60-90 lm/W per luminaire. Manufacturers often provide tolerance of 10% on the nominal data for lighting products. In practice, however, the actual efficacy of cheap imported luminaires may be more than 30% worse from the declared value. The low cost of replacing traditional fluorescent lighting with LED tubes may have a decent return of investment time, even with an efficiency below 100 lm/W for the luminaire. However, the problems with differences between declared and actual parameters of products imported from China mentioned before still may occur.
It is different in the case of dedicated LED luminaires; their light efficiency is 160-170 lm/W. The higher investment cost is compensated by the higher efficiency and less energy consumed. It means the overall return of investment time may be at a similar level, but with additional advantages. Energy saved thanks to the higher efficiency of dedicated LED luminaires means that after this time the level of savings increases; sometimes the difference may even cover the full cost of lighting the facility.
Before the lighting system is designed and the light sources replaced, there should be an audit carried out to assess the state of the existing system to choose the best solution to be implemented. When traditional fluorescent lamps are to be replaced with LED tubes, the audit is simplified, but the proposed option should meet specific standards regarding the expected light intensity in a given working space. Meanwhile, the audit for replacing the existing system with LED luminaires is more detailed and requires more work. Besides, it takes into account the maintenance factor (20% of intensity loss). The consequence of this solution is the guarantee that the lighting intensity will be maintained following the standards even at the end of the expected lifespan of a luminaire.
When replacing traditional fluorescent lamps with LED ones, a 1:1 substitution is made without designing the whole lighting system. This means that, in the best case, we can achieve normative intensities on the day when the implementation is finished, but this does not take into account the decrease in intensity caused by the degradation of LED lamps during their lifespan. The average life of LED lamps is 20,000h on average for the L70 (70% of the initial luminous flux). As a result, we may create a lighting system that after 1-2 years of use will not meet the standards and requirements of light intensity, so we may have to replace it with new LED tubes. The low cost of initial purchase may make it sound tempting for the owner of the building, but you should remember to take into account the cost of manual works and the risk associated with lighting quality and modifications of luminaires.
In contrast, a dedicated LED luminaire has an expected lifespan exceeding 100,000h for L80 degradation (80% of the initial flux). Besides, we are sure that the design created during the audit guarantees that the normative intensities will be maintained throughout the whole lifespan of the system. The level of savings can be further increased by adding an active lighting control system that allows you to smoothly adjust the amount of light that is needed; when we replace traditional lamps with LED tubes, we don’t have such a possibility.