Why switching to LED lighting can be cheaper than you think REPEATED

One of the main energy efficiency measures currently suggested is replacing tubular fluorescent lamps with equivalent 18W or 20W LED lamps. There are several reasons to justify this replacement: a 50% reduction in lighting power consumption, a significant increase in their useful life, prevention of mercury disposal, and the possibility of integrating them with presence and dimming sensors, which further reduces consumption.

Despite this, most directors and managers still consider the transition to LED technology to be very expensive, and claim that there is no available funding to make this investment. Today, the vast majority of existing buildings (particularly offices) are lit by tubular fluorescent lamps, of the T8, T10, or T12 type, with power ranging from 32W to 40W.

The nomenclature of these lamps has the letter “T” for tubular, the number that follows represents the diameter of the tubes in eighths of an inch. For physical reasons, especially the area/volume ratio, thinner lamps such as T5 are the most efficient.

For some time, we have suggested replacing T8 or larger bulbs with T5 instead of LED as an alternative until LED prices became more affordable. The T5 fluorescent lamp is more efficient than the T8 – while the former has a power of 28W, the latter is 32W, for the same level of lighting. In addition, T5s cost only 10% of the price of an LED, which is why most of the market believed that this was the most attractive alternative.

However, the T5 has a smaller diameter and uses a different type of base (G5 instead of G13) and, therefore, is not compatible with common T8, T10 or T12 luminaires. Furthermore, a T5 needs a new ballast.

Therefore, considering that all the luminaires and all the ballasts would have to be replaced as well, the cost most of the time exceeds the final value of implementing LED lamps, which do not require a ballast, can be easily found with the G13 base and, therefore, there would be no need to replace the luminaires.

When we calculate the simple payback of replacing 40W T10 lamps with 28W T5 or 18W LED, we often see that the financial return of replacing them with T5 takes longer than that made possible by LED.

Example of savings calculations Replacing a 40W T10 with a 28W T5 and with an 18W LED:

*cost composed of the cost of the lamp + ballast and luminaire (1 for 2 lamps)

Considering that the purchase cost of the T5 system is already higher than the purchase of only LED lamps and the energy consumption of T5 is higher, there is no doubt that the second is the best system to choose.

Another important point in switching to LED is the technology: this type of lighting is the only one in which presence sensors can be incorporated, for example, which can further reduce energy consumption.

With new constructions, the story is different

When we talk about the best alternative for installing a lighting system from scratch, the choice is not so simple. In this scenario, LED lighting loses the initial advantage of not needing new luminaires and the bill can be quite different. The results vary greatly depending on the number of hours the system will be used and the rates, as shown below:

* cost composed of the cost of the lamp + ballast and light fixture (1 for 2 lamps)

** cost composed of lamp + light fixture (1 for 2 lamps)

In conclusion, in this system, the LED option would be R$8,214.00 more expensive and would save R$5,533.45 annually. This means that the additional investment “pays for itself” in 18 months, not to mention the other benefits of LED lighting mentioned above.

It is worth noting that the results vary greatly depending on the energy tariff (in this calculation, R$0.48/kWh was used) and also depending on the number of hours that the lighting is used annually.