Wednesday, March 21, 2012

HPS(High Pressure Sodium) vs LED lights


            HPS vs. LED
Today we are going to compare High-Pressure Sodium (HPS) with LED. Based on the knowledge we learned about LED before, we basically know that LED lights are more efficiency, more energy saving, more durable than incandescent lights and compact fluorescent lights (CFL). However which one is better if compared with HPS? Well, we may see the below indexes for answers.
Beam Angle
We know HPS has 360 degree lighting angle which may means some lumens does not go where they should. If the light is not 100% used to the places we want, then we may consider the rest of the light as wasted. However LED lights don’t have this problem. The LED factories use lens or light guiding pillar to guide the light to the appointed places but this doesn’t mean LED can deliver light anywhere we want it to go. It also has limitation due to lamp shapes.
Lifespan:
LED lights are also famous for their long lifespan. A LED lights can last for 50,000 hours and some even last 100,000 hours if with good encapsulation form and good chip. The life time of HPS lights are far less than LED. Their life last about 2,000-20,000 hours.
Light Decay
Life is like marathon. Many people getting tired as the time goes. Some become exhausted after a long time running. So do the lamps. They may want to light up our home or road forever but the fact is we have to replace them with other lamps after using a period of time. The LED lights decayed about 1%-10% after 10,000 hours using and about 30% after 50,000 hours. How long is 50,000 hours? If we use the device 8 hours per day and it will last for over 15 years, which is quite a long time. Of course we didn’t take other facts into consideration that the bulb may breakdown. Compared with LED, HPS lights work without much decay during the late period of life but HPS lights decay a lot at the beginning of using.
Cost
The cost for LED lights is more expensive than HPS lights as we all know. However the electricity charges and the replacement charges that we spend for HPS are enough to buy a LED light after a few years’ using. This insignificant change from HPS to LED is not only good for us but also make the world better! Why not do it right now, start right now replacing your own house with LED!! you will feel the difference on your utility bills.
Color Rendering Index
The color rendering index (CRI) shows how “true” the object may look when lightened. The higher CRI, the more natural the objects look. The CRI of white LED is over 75 normally, some well-encapsulated LED can reach over 90, which makes the object looks like in daylight even when placed in darkness. While the CRI of HPS is much weaker, with a CRI less of 23, and the objects lightened appear yellow (see below photos).
Color Temperature

The color temperature of LED ranging from 2600k to 10000k according to different functional lumination requirements. There are warm white, pure white and cold white for your option. The color temperature of HPS ranging from 1950k to 2250k.With a yellow light, it makes people feel warm and sometimes sleepy. Therefore many bedrooms are fixed with warm white lights. The warm white color of LED also has such effect. What’s more, LED can emit pure white color which makes you feel like in the daytime. This effect is good for street lighting in the night. See the two photos of LED street light and HPS light below:
 LED Street Light with natural lights Colors

HPS Street Light with yellow lights color


 
Which one would you choose----LED or HPS?  YOU make the choice!!

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