(The picture above shows the difference bewteen LED (left) and High Pressure Sodium (right) Lamps)
Last semester I took a lighting course. In this class we discussed color rendering, types of luminaires, Photometric reports, and illuminance levels. This topic is relevant to the current electrical industry in buildings. We discussed LED lights and how they are replacing High Pressure Sodium Lamps. As of right now one of the most popular luminaires used are High Pressure Sodium Lamps. Recently the LED industry has made vast improvements in their technology, which has allowed them to enter the lighting market. In comparison to High Pressure Sodium Lamps, LEDs are superior in every single way except cost and this shall change as they become more prevalent in the industry. LEDs have longer life times, a higher Color Rendering Index (CRI), and the fixtures have a higher efficacy. They also have better control of the overall lighting system. Since LEDs are so new to the market, they have had their problems. Starting out they were only available in one color, white, which is unfortunate for the Christmas industry. They also had some troubles with heat dissipation that caused premature failure. In the past this was a huge problem. Until recently they did not have replacements for LEDs, before you would have to replace the entire light fixture, instead of individual parts of the light engine. At first they also caused a lot of glare, because there was lack of control in the lighting system. This particular bug has been accounted for by directing the light with lenses over each individual LED. As with any new technology, LEDs had troubles when it first stared out, but the necessary fixes have been made. They have come a long way in a short time and show promise of vast improvements in the near future and at some point will replace High Pressure Sodium Lamps almost completely.