What is an LED?

LEDs are semiconductor diodes, electronic devices that permit current to flow in only one direction. The diode is formed by bringing two slightly different materials together to form a PN junction (Figure 1). In a PN junction, the P side contains excess positive charge (“holes,” indicating the absence of electrons) while the N side contains excess negative charge (electrons).

Figure 1. A simplified PN junction diagram

When a forward voltage is applied to the semiconducting element forming the PN junction (heretofore referred to as the junction), electrons move from the N area toward the P area and holes move toward the N area. Near the junction, the electrons and holes combine. As this occurs, energy is released in the form of light that is emitted by the LED.

Performance differences between incandescent, fluorescent and LED lights:

• Incandescent bulb wastes 90 percent of their power as heat output and delivers roughly 16 lumens per watt.
• Fluorescent delivers 100 lumens per watt.
• LED can delivers up to 250 lumens per watt.

Benefits of LED Lighting

LED light bulbs can save you money not only because they are roughly 80% more energy efficient than other bulbs, they also produce far less heat than metal halides, CFLs, and incandescent light bulbs. Upgrading to LED lighting means you won’t spend your summer months cooling down rooms that your light bulbs are busy heating up. While originally a cooler blue tone than incandescent bulbs, LEDs now come in daylight and warm white color temperatures so you can more easily replace your existing bulbs without altering the color of your room. LED lighting also offers a superior color rendering index (CRI), so you can see the colors of your artwork or makeup more accurately.

LED replacement bulbs are durable and ecologically friendly. Did you know you can recycle LED bulbs and reduce your carbon footprint up to one third? LEDs outlast the competition, staying bright for up to 25 years and CFLs can last up to seven years. LEDs are one of today’s most promising technologies.

• No mercury, making them a cleaner alternative to fluorescent and CFL lamps.
• The lowest energy consumption of any lighting product to date.
• Light quality equal or superior to traditional lighting products.
• Life that is 20 times than some traditional lighting products, on average LED offers more than 22.5 years of lifespan.
• Maintenance free
• LED light bulbs can reach full brightness in a matter of microseconds.
• Dimmable – Preserve their original color when dimmed.
• Versatile – Fulfill different purposes and functions. Homes, Parking lots, Warehouses, Manufacturing, Street Lighting etc.
• Environmental friendly – Reduce carbon footprint and contains no poisonous mercury or lead that can leach.  No Infrared or Ultraviolet Emissions.

LED also plays an important role in the classroom

A standard incandescent bulb emits light at 10 percent efficiency, which means 90 percent of the energy it expends is purely heat. Conversely, LED lights work at approximately 80 percent efficiency. Not only does this help conserve energy, but it cuts down on electricity bills as well.

Unlike fluorescent tubes, LED lighting does not contain any dangerous mercury or other compounds that could harm students should a light break in the classroom. As mentioned, the lights do not emit as much heat as their incandescent counterparts do, reducing the risk of children burning their fingers. In addition, they do not shatter when hit or dropped as fluorescent and incandescent lights are prone to do.

LED lights may actually help students stay calmer and more focused. First, they do not produce any humming sounds like fluorescent tubes often do, nor do they flicker when they are faulty or old, meaning one less distractions for students (and teachers) to try to work around. In addition, the cool, white light of LED lamps is the most similar to natural sunlight, so it diminishes eyestrain and fatigue. Finally, many students and teachers find the lighting more soothing than the glaring illumination of fluorescent or incandescent lighting, delivering an environment more conducive to learning.

Optimized lighting conditions help students improve performance

Students working under artificial LED lighting designed to simulate daylight showed improved concentration and classroom performance.
Published on:Jun 11, 2012
By Tim Whitaker

A recent study has demonstrated that artificial lighting simulating daylight was able to increase concentration and cognitive performance in students.

The so-called “biologically-optimized” lighting used in the study was produced by combining blue and white LEDs.

The study investigated the effects of light on the performance of students at two schools in Ulm, Germany. It was carried out by the ZNL TransferZentrum für Neurowissenschaften und Lernen (Transfer Centre for Neuroscience and Learning) in conjunction with lighting manufacturer Osram between November 2011 and February 2012.

The results showed that students working under biologically-optimized classroom lighting achieved better results than the comparison group in standardized tests for concentration ability, and their performance speed also increased.

ZNL and Osram began the field study in November 2011 at the Ferdinand von Steinbeiss School and the Robert Bosch School in Ulm, Germany. In each case, one classroom was fitted with the biologically-optimized light. The students, ranging from 17 to 20 years old, attended classes both in the classroom with the new lighting and also in classrooms with conventional lighting.

During the study, the students had to repeatedly take various standardized performance and concentration tests, such as Brickenkamp’s d2 test of attention (see below for details). The test results were compared for biologically effective light in relation to conventional lighting.

LEDs create artificial daylight

The biologically-optimized lighting was implemented using blue and white LEDs. Osram enhanced an LED light developed by its subsidiary company Siteco.
Lessons at the Robert Bosch School in Ulm, Germany under biologically-effective lighting.

“In order to create an artificial sky in the classroom, we use strips with blue and white LEDs that can be controlled independently of each other,” said Hannah Helbig, Innovation Manager at Osram. “Therefore, the light colors can be mixed dynamically and reproduce the color temperature of the sky inside the building.”

Katrin Hille, head of research at ZNL, who was in charge of the light study, noted the positive effect of the new lighting. “Even though it has been recognized for a long time that light with a specific color temperature and illumination intensity has a positive effect on people’s performance and well-being, the fact that the students with the biologically-optimized lighting had up to a third fewer errors in the concentration test is impressive,” she said.

Benefits for students and teachers

According to the researchers, the biologically-optimized light provides stimulation to the body as if the person was outdoors. This causes the students’ circadian rhythms to shift forward (in time) so that they are alert earlier in the day. The researchers say this can counteract “social jetlag” i.e. tiredness in the mornings frequently observed in young people in particular.

Many participants in the study were enthusiastic about the new lighting. “My concentration is actually better,” said one student. “In normal light, however, I sometimes have to keep myself awake in the classroom.”

It is not only the students that appreciate the new light – so do the teachers. “Many teachers, even those that were skeptical about the new lighting at the beginning, told me at the end of the study that they are also now feeling better,” said ZNL researcher Oliver Keis, who also worked on the study.

Brickenkamp’s d2 test of attention

The d2 test is a standardized, more developed version of the cross-out test. It measures the speed and accuracy of a person’s working behavior when differentiating between similar visual stimuli (detail discrimination), so it allows evaluation of their individual performance with regard to attention and concentration.

Equivalent wattages and light output of Incandescent, CFL and LED bulbs