The ABCs of LED energy efficencty

With the introduction of white LED technology many voices heralded a new age of energy savings and cleaner environment. A few urged caution because of the numerous new applications of light that LED technology promised to make possible, each adding to the total energy consumption of human activity.

Now, more than a decade later, the matter is still in suspension. LEDs with lower energy consumption successfully replace other light sources but they also make artificial light to become even more ubiquitous.

LED modules and strips, as a driving force of LED light, should be champions of energy efficiency

Take the example of the very popular LED modules and strips in which we, at Ledrise, specialize. We have 35 standard variations of rigid Nichia LED strips, 6 of flexbile Nichia LED strips, 31 of led modules and on top of that we can custom build all with a large choice of size, LED number, brightness and color temperature.  Considering the choice of almost 100 LEDs of middle-high power from Nichia, the possibility to add light to pretty much any object or architectural element is within reach.

This trend is very visible both indoors and in outdoor installations. Lines or large plains of light are the hallmarks of modern architecture, while outdoor architectural lighting and illuminated signs of all shapes and sizes have become a lot more common place.

While us or the lighting industry cannot stop people from lighting up whatever they want, we have a moral obligation to guide them to the most energy efficient solution.

The ABCs of energy efficiency

A lighting installation can be energy efficient in three ways:

A) The light is emitted with the lowest possible energy consumption.

This is called luminous efficacy and is measured in lumens/watt. Below is a general example about the common bulb.

B) The total light output of the installation is at an optimum, as defined by its purpose or the activities it needs to support.

In other words, the number of light sources and the light they emit is not more than what is needed and the light beam is properly directed.

What is needed is often defined by iluminance and lluminance recommended values as defined by national, international bodies and/or research. In brief, illuminance is the light falling on a surface while luminance is the light reflected by that surface in the direction of our eyes. If these values for an installation are too high then energy and many other resources are wasted.

C) The composition of the white light is on tune with the sensitivity of our eyes.

The composition of the white light is defined by its radiant power and wavelength graph, with some examples below.

As all of us have noticed, the sensitivity of our eyes changes based on the perceived total brightness of the ambient around us. Under bright light our eyes change to low sensitivity mode called photopic vision, as the light gets dimmer the high sensitivity mode is gradually activated, called scotopic vision. Simply put, during the day we use photopic vision and at night scotopic vision. Based on the this, our eyes are have a different sensitivity to the components of white light.

If we compare the sensitivity at night or low light conditions to the spectrum of a cool white LED and warm white LED we can draw the conclusion that the perceived brightness (luminance or illuminance) of  the two light will not be the same even if their luminous flux (total emitted light) is.  During the night a 1000 lumen cool white LED will seem a lot brighter than a 1000 lumen warm white LED due to their different spectrum:

With this knowledge it is possible to obtain the same useful effect by using LEDs with fewer lumens and hence reduced energy consumption with the condition they have the right light spectrum and color temperature.

Only by following the ABCs of energy efficiency we can truly say our installations are  energy efficient and friendly with the environment. Inefficient light sources that emit too much light than their designed purpose and are not adapted to the sensitivity of our eyes waste energy and valuable resources three fold.

In our case, we can ensure that a lighting installation is truly energy efficient by combining the great variety and high performance of Nichia LEDs with our ability to custom build modules and strips and knowledge about lighting.

For a personalized quote for a custom build LED module or strip perfectly adapted to your application you can contact me via Linked In or at [email protected]