The US Department of Energy (DOE) has published the final report from a roadway lighting demonstration conducted in Palo Alto, California, to evaluate the feasibility of replacing high-pressure sodium (HPS) streetlights with LED and induction streetlights. The report is the tenth in a series, all of which can be downloaded from the Gateway website.
In this project, three groups of HPS streetlights were replaced — four with one type of LED luminaire, three with another type of LED luminaire, and three with induction luminaires — allowing comparisons between the three groups as well as to the existing technology.
In addition, two LED and two induction luminaires were installed on a commercial street in the center of Palo Alto to test a remote streetlight monitoring system. These luminaires were equipped with Echelon communication hardware that can be remotely controlled through a desktop or laptop personal computer. These luminaires were programmed to turn on and off on a schedule similar to that of the streetlight luminaires controlled by a photocell but then were dimmed by 25% of full power for 5 hours each evening.
This report provides an overview of project results including lighting performance, economic performance, and potential energy savings.
Key findings include:
- Of the three roadway lighting systems (induction, HPS, and LED), LED used the least energy (44% reduction compared to the baseline HPS) and provided comparable average illuminance on the street.
- LED luminaires produced more uniform light output than HPS or induction luminaires, and had better cutoff on the curbside, resulting in significantly reduced light trespass onto residential properties.
- Simple payback for retrofitting a 70-watt (nominal) HPS with an LED luminaire was estimated to be around 12 years, improving to about 10 years in a new construction scenario.
Community feedback was obtained during this study, and overall results from respondents show a marked preference for LED lights over induction lights. Nevertheless, two common concerns related to LED lights were excessive glare and the perceived blue/cold color of the LED light output. These issues will have to be resolved prior to a mass rollout of LED streetlights for Palo Alto. The LED luminaires tested in the demonstration have a correlated color temperature (CCT) of 6000K; by comparison, the CCT for the induction and HPS streetlights were 5000K and 2100K, respectively.
|
| Name: downey Posted: Wed, 16 Jun 2010 20:06 |
| After reviewing the application it is very apparent that this test was misconceived from the start. The best solution would have been to bypass the existing ballast and replace the HID with a self ballets Induction bulb cost $80.00 service life 100,000 hours. We call your approach a $100.00 answer to a $10.00 problem. Knowing the DOE only a LED solution will do so bypass the ballast and screw in a LED street light (SP90) replacement bulb cost $150.00 service life 30,000 hours. We are using LED and Induction in the real world every day. Typically with induction you cut the energy in 1/2 and the bulb service cost to zero for 23 years. Our ROI with the real world is about 2 years. You replaced a bulb with a higher wattage bulb and then do a study to find out why it doesn't save energy. I hope you didn't spend a lot of time and money on this because I know we all have better things to do. | | Name: exseabee Posted: Thu, 17 Jun 2010 02:06 |
| I am not sure about the numbers in this test? I am very sure that the Borealis brand LED street lights used for a test by the City of Naperville, Illinois did better than the 44% in the article! Google will find the posted results from the cities testing, they used 57.6 as their energy reduction number! Their tests were a 120-watt LED versus a 350 watt H.P.S. the idea was to try to keep the lumen output as close as possible! | | Name: lightbuddy Posted: Sat, 19 Jun 2010 16:06 |
| Induction lighting appears to use mercury (and vaporize it while in use) which is undesirable if a comparable non-mercury technology is available. | | Name: s&ssales Posted: Wed, 07 Jul 2010 20:07 |
| I thought the findings for this study were done very well and appreciate the fact that DOE did a study linking HPS, induction and LED light sources. It is my personal opinion that LED does a much better job of distributing the light where it needs to be than either HPS or induction. As for the first person's comment about just replacing the lamp that is the problem with the lighting industry today, too many people think a lamp will perform the same in a fixture as it does bare bulb. With HPS and induction the life of the lamp is figured at lining up 100 lamps and the hour at which the 51st lamp has burned out is the life of the lamp - bare lamp in a socket with no concurring heat issues to go along with it.
At least with LED the heat issue is figured into the fixture and the fixture is rated with a hard fact life rather than rating the lamp and hoping it gets that in the fixture which it will not. |
|
