How to Overcome Outdoor Lighting LEDs Thermal Management Issues

outdoor led neon lights

While the compact florescent light bulb has been an energy efficient option for more than 20 years, consumers were actively encouraged to replace incandescent bulbs with CFLs,  with the idea that the simplest change could have a lasting effect on energy consumption just in the last 10 years. Used both internally and externally, CFLs did change the lighting industry, but on its heels and destined to make an even larger impact in energy consumption, was the introduction of the LED for lighting.

In 2006, LEDs were introduced as a safer and more energy efficient option for Christmas tree lights, but the energy savings do not, and will not, stop there. LED lighting has advanced leaps and bounds over the past three years, with real reliable solutions available to replace the common 75 to 100 watt incandescent bulb, and high brightness LED Neon lights are now looking to save the environment by addressing outdoor lighting solutions.

The current cost of outdoor lighting to municipalities, retailers and even home owners is substantial. Retrofitting fixtures or replacing classic outdoor lighting solutions with LEDs stands to save millions of dollars a year in energy costs, but there are still advancements that need to be made to outweigh the cost of installing these energy savers in the first place.

Current limitations for outdoor LED lighting center around the lumen output not being sufficient for use case needs. While LED technology is advancing, these needs cannot be reached with the current thermal management solutions in place for outdoor lighting designs, most notably passive cooling. LED lights cooled by a passive heat sink rather than by an active cooling solution like SynJet are inherently larger, less reliable due to heat damage to the LEDs, less flexible and produce less light.

As manufacturers discover how to solve the thermal, weight and size issues at reasonable costs with minimal additional non-lumen producing power required, they will then develop viable products delivering more lumens in the right places. With the capital cost for installation and greater weight and larger size for wind resistance of the supporting pole added in, the argument for active cooling is even more persuasive. Government standards and legislation are also providing a powerful impetus.

Cost of Outdoor Lighting

outdoor neonStreet lighting costs represent a huge chunk of a city’s utility bill, accounting for 10 to 38 percent of the total bill. And, of course, the more streets that need to be lit, the more those costs rise. The City of Los Angeles estimated in early 2009 that its streetlights use 168 gigawatt hours of electricity at an annual cost of $15 million, and emit 120,000 metric tons of carbon dioxide – the equivalent of an additional 15 thousand cars on the road emitting environmentally unfriendly gases into the atmosphere. Additional costs to the government, such as general maintenance and replacement, increase the expense of outdoor lighting.

The average household dedicates nearly 19 percent of its energy budget to lighting. A large portion of that goes to support outdoor lights used for decoration and security. Because outdoor lights are usually left on for extended periods of time, extensively longer than indoor lights, reductions and energy efficient lighting solutions can save homeowners significantly.  The U.S. Department of Energy estimates as much as 50 to 75 percent of their lighting bill.

Cost of Outdoor Lighting with LEDs

The City of Los Angeles, through a partnership with the Clinton Climate Commission (CCI) set out to lower its electricity costs by retrofitting street lights with environmentally friendly LED lights where they were available. This program, the largest city retrofit to date, stands to save the city $10 million annually through reduced maintenance costs and a 40 percent energy savings.

LED lighting solutions are not just energy efficient. They also have an extensive lifespan, which leads to the reduction in maintenance costs. A typical streetlight lamp will last from four to six years, but an LED fixture has an estimated life span of 10 to 12 years. Additionally, LED lighting solutions are generally more durable and damage-resistant than classic outdoor solutions. More power into the LEDs gives more lumens out. The useful (L70 typically) lifetime of the LEDs is significantly reduced if they operate too hot. If the temperature is controlled, both lifetime and efficacy are improved.  Plus, their drive circuits are more reliable when cooler.

If LED street lights can be actively cooled, there is the option of installing higher lumen/brighter fixtures; fewer would be needed per highway mile or per parking lot acre. Smaller fixtures require less weight and substance in poles and supports and cooler LED temperatures helps the luminaire reliability; all resulting in a significant capital cost benefit.

brighton neon

Limitations of Outdoor Lighting with LEDs

While the potential for LED lighting in outdoor spaces is near limitless, there are several thermal management and design issues that must be addressed prior to a wide-spread adoption of outdoor LED lighting occurs.

Currently, LED lighting solutions have a hard time meeting the lumen requirements demanded of the outdoor use case. In order to reach the extreme high brightness demanded for outdoor solutions, LED lights can produce significant amounts of excess heat. The heat produced must be addressed by active cooling in order to accommodate size and design constraints for outdoor solutions.

High temperatures also severely hamper the life expectancy of an LED lighting solution. In order to meet the projected life span previously mentioned of 10 to 12 years for outdoor LED lighting solutions, the LEDs will need to be actively cooled to increase the lumen output, as the bulk of a heat sink big enough to dissipate the produced heat would create bulky and unwieldy design fixtures.

Lastly, some active cooling solutions such as fans don’t have the same expected energy efficiency and life expectancy as the LED itself. In order to create a viable active cooling solution, the method of thermal management must be inherently low in energy consumption and have an expected life equal to or greater than that of the light.

How SynJet Can Help

LEDs allow the ability to distribute light sources and shape the lighting for better uniformity and boundary control, very important in alleviating light pollution.  LED color temperature can also be tuned to provide the best spectral content.  All this can be helped with SynJet cooling as cooler color temperature equals more watts to enable more lumen output.

The SynJet form factor significantly lends itself to the design of any LED lighting fixture and outdoor lighting is no exception. SynJets have the unique ability to bend air flow in ways that are nearly impossible with traditional air movers, allowing for unique luminaire designs.

Finally, the form factor of the SynJet also lends itself to durability, which is essential in outdoor lighting. The modules contain frictionless moving parts which make them reliable (10x the reliability of fans), long-lasting, resistant to dust and particle contamination and virtually silent.

For all of these reasons, the SynJet was chosen by Evluma to provide active cooling within the company’s security outdoor lighting solution (shown here). The Evluma light puts out 2,500 lumens, replacing 175 W MV or 150 W HPS lamps.

Outdoor lighting is the second largest electrical energy savings opportunity after indoor lighting and most of the Department of Energy conservation projects focus in this area.  As these projects are bid out, several different energy saving techniques are being reviewed – from compact florescent lights and LEDs to automatic controls and motion monitoring.  It is essential for a successful campaign that the very best LED solution be considered. This requires an active cooling solution to allow LED lights to perform up to their expected capabilities and efficiencies.  SynJet technology is the only proven active cooling solution that can answer all the demands of outdoor lighting designers while maintaining the durability and efficiency promised of LED solutions.