The World Needs Higher Efficacy! But what else?

The energy consumption of general lighting represents a significant portion of the worldwide energy demand. It's about 8% of the total and thus has its related contribution to global warming. Well, assuming that the scientists are correct with the global warming forecast in general. But that's a different story. If there is a problem, we should work on it, now.

In the not too distant future, solid state lighting (SSL) will become the predominant light source for general illumination. But why will this happen? There is no doubt that incandescent light has very poor efficacy vs. SSL, but is at very low cost. Legislation took the first steps to ban those lamps and one does not need to be a prophet to forecast the death of this old-fashioned light source. With regard to fluorescent light, the situation is a little different. Today, the efficacy of SSL is about the same as that of a fluorescent light source. So where is the advantage? There are many: longer lifetime, better colour management, less toxic "ingredients", easier to dim, instantly to the desired brightness, just to mention a few. There is at least one more very important advantage that will outperform the fluorescent light by far: The amazing efficacy potential of SSL technology. It took 40 years to increase the efficacy of fluorescent lamps, from less than 75 lm/W (lumens per Watt) to around 100 lm/W. SSL light source manufacturers are in a breathtaking race for ever higher efficacy limits. The race started just a few years ago and recently we heard the 200 lm/W barrier was breached. New records are seen every few months. How long will it take to achieve 300 lm/W? When will we see 400?

There is more than "just" efficacy. What else can we do? The answer is simpler than one may think: provide light, only when we need it, only where we need it, and only how much we need, not more

• Source efficacy (the SSL device itself)
• Power supply efficiency (LED drivers)
• Fixture efficacy (reflector, lens, etc.)
• Light distribution efficiency (where)
• ‘Light provided' vs. ‘light needed' efficiency (when and how much)

As a semiconductor supplier, National Semiconductor provides a wide range of energy-efficient PowerWise® LED drivers, and continuously strives to increase the efficiency of the SSL power supply. When, where, and how much are the additional questions we need to ask ourselves. By answering these questions and finding intelligent solutions to solve the challenges involved, we will discover huge additional possibilities for energy savings. These intelligent solutions are not very common today, but carry a great business potential.

Let us look at the overall efficiency of a parking garage. What is the efficiency of its light sources on the 5th floor of a parking garage at 3AM with not a single person being around? What is the resulting efficiency if we provide x-times more light than necessary? And what's the light efficiency when there is so much ambient light that no one can tell that it is on? Of course, it's not a simple task to manage the light in such a complex environment. Furthermore, if a fluorescent light were to be switched on and off frequently, depending on the type of ballast, the lifetime would be negatively impacted. So, better that we leave it on all the time! SSL sources do not have this negative effect. Also, when they are off, their lifetime extends. This is a perfect example demonstrating the need for light management systems that keep our lives easy and comfortable but save energy as much as possible.

National Semiconductor continues to work on increasing efficiency/efficacy of SSL lighting solutions. The next step in front of us is to install wise (PowerWise®) light management technologies everywhere. Remember the garage example above. Because a lamp that is not ON, saves the most energy. www.national.com