Lighting designers, lighting specifiers and manufacturers of outdoor lighting fixtures are in a quandary about whether they should be using High Pressure Sodium (HPS) bulbs over LED lights.
The hot question right now is whether people actually favor white light over yellow light. Here is what could be asked regarding the preference:
- Does LED light provide the broad spectrum white light that is conducive to night vision for both pedestrians and drivers?
- Which type of light source is more pleasing to the eye?
- Which light source is more cost effective in the long term?
- Which light source is more energy efficient?
LEDS cut energy usage by over 50% when compared to using HPS lamps. So, in this case, they are more energy efficient. Remember, these bulbs/luminaires are being used for street installations in commercial applications, not residential projects. LED lamps also have a longer lifetime (about 60,000 hours when using a 67 watt bulb, then a HPS, which usually last about 20,000 to 30,000 hours, using a comparable 90 watt bulb.) Generally speaking, most people prefer the white light emitted from the LEDS over the yellow light coming from the HPS lamps.
LED bulbs are more expensive (but coming down in cost as the demand continues to grow) than HPS bulbs since they last twice as long as High Pressure Sodium bulbs (with a life expectancy of up to 15 years depending upon the type of streetlamp). This last feature truly makes them more cost effective since they don’t need to be replaced as often as HPS lamps, thus also reducing maintenance costs in the long run.