e-News #94: Lighting Performance Advances

September 17, 2014
 
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New Sources & Controls

Through the past 20 years, new lighting technologies have been a major driver of increasing energy efficiency in buildings. Lighting specifiers and consumers have embraced CFLs, LEDs, and other highly efficient lighting options. Such widespread acceptance in the marketplace is due in large part to their increasingly predictable performance and reduced product costs. So, how can even more efficiency savings be mined from the lighting end use?

Tubular LEDs

The advent of tubular LEDs (TLEDs) would seem to offer many possibilities for saving energy and maintenance costs with the millions of 4’ fluorescent lamps installed in commercial space across the nation. However, several issues with this technology require some attention.

Tubular LEDs
Figure 1. Tubular LEDs (TLEDs)
Image: Architectural Energy Corp.

TLEDs, as shown in Figure 1, are configured in many different ways and, as a result, one size does not fit all. As can be seen by the variety in TLED arrangements in Figure 1, the light distribution does not equal that of a fluorescent T8 which by design radiates light in 360 degrees.  Light distribution, thermal performance, light quality, and ease of installation all need to be considered.  Most importantly, installation safety concerns and compatibility rise to the top of the list.

In the field, existing fluorescent fixture components already vary.  Existing fluorescent fixtures allow for varying degrees of heat dissipation, have rapid start, instant start, and/or dimming ballasts, and lamp holders that are wired according to the ballast type. 

TLED retrofit technology options vary, too.  TLEDs have electronic drivers in place of ballasts and require attention to heat dissipation. 

Depending on the application, re-lamping or retrofitting fixtures with TLEDs often requires electrical modifications; ballasts are either replaced with the electronic LED driver, bypassed, or included in the wiring circuit.  To complicate matters even more, TLEDs obtain power from one end of the lamp, both ends of the lamp, or none of the lamp holders depending on the design. 

As the technology evolves to address safety issues, manufacturers have designed TLEDs for one-to-one fluorescent T8 lamp replacement.  One key feature is to require no extra wiring and specify compatibility with existing electronic, instant start ballasts and sockets.

Another caveat regarding TLED upgrades:  they cannot subsequently be “downgraded” to their original fluorescent lamps or even other TLEDs necessarily.  To prevent this from happening, fixtures should be affixed with manufacturer-supplied labels once retrofitted for TLEDs to inform anyone who works on them in the future.  Similarly, LED and fluorescent T8 lamps should not be used within the same fixture.

As with any lighting retrofit, ensure all safety concerns are addressed and consider the basics of good lighting system design: light distribution, light quality, and maintenance.

Some items for consideration include:

  • Follow TLED manufacturer instructions for compatibility.
  • Be aware that the installation may require a qualified electrician.
  • Consider the TLED label designation.
    • Is this a UL Listed product?  This designation is applied to complete systems such as TLEDs that are one for one replacement with no ballast change or electrical disconnection required.
    • Is the kit UL Classified?  This could include LED retrofit kits and replacement lamps that require disconnection of the original ballast and re-wiring might have this designation.
  • Refer to the DesignLights Consortium® Qualified Product List.

Lighting Controls

DesignLights Consortium®

The DesignLights Consortium® promotes quality, performance and energy efficient commercial sector lighting solutions through collaboration among itsfederal, regional, state, utility, and energy efficiency program members, luminaire manufacturers, lighting designers, and other industry stakeholders throughout the U.S. and Canada.

With advanced lighting control technology, potential electricity savings of 50 to 90 percent of the total lighting energy use are now possible.  In addition to such substantial savings, some advanced lighting systems offer flexibility in scheduling, improved light quality, increased employee satisfaction, the ability to track costs, remote control, and demand response.

One of the newer control technologies is wireless communication from a central controller which sends commands between sensors, switches, and LED drivers.  Often, these wireless systems use a “mesh” architecture for communication where data passes from device to device using the most reliable communication links and the most efficient path until the command’s destination is reached.  These systems are being employed both in new construction and in projects where existing fixtures are being replaced.

Table 1 shows some wireless system features along with estimated energy savings for each.

Table 1. Wireless system features and estimated savings

Table 1. Wireless system features and estimated savings

Some companies provide the wireless network communications and control software independently, while other partners provide compatible devices such as switches, sensors, ballasts, and LED drivers.  Other lighting manufacturers offer integrated packages in which they provide not only the lighting fixtures, but also a wireless communication solution.

In the packaged scenario, fixtures typically come with a motion detector, a light sensor, and a wireless communication device that interfaces with a remote control and other light switches.

A recent study by NEXANT described one example where a California manufacturer of machine tools employed a wireless lighting control system for their office and warehouse areas. The office area fluorescent fixtures were replaced with LED fixtures with dimming, task tuning, occupancy sensing, and daylight harvesting. Metal halide fixtures in the warehouse were replaced with dimmable LED fixtures with motion sensor control.

The study estimated that changing from linear fluorescent to LED lighting accounted for up to 61 percent of energy savings in this instance.  If the LED lighting is accompanied by controls it saves up to 63 percent of energy savings. The simple payback without utility incentive for this retrofit project was nearly 9 years based on the project’s cost, but with a utility rebate the payback period was reduced to 3 years.

However, NEXANT concluded in their study that retrofitting existing offices with advanced lighting controls may be a tough sell without significant rebates or financial incentives from electric utilities.

Dimming Lights

Dimming strategies can be used to reduce energy in a number of ways, as described in Table 2.  In fact, new Title 24 standards require dimming ballasts for efficient lighting control systems.  These increased savings expectations have placed the performance of fluorescent dimming systems under some scrutiny.   

 

Table 2. Dimming control strategies

Table 2. Dimming control strategies

The prevailing assumption of light output vs. energy savings has been that “the energy consumption is roughly proportional to the amount of the light produced throughout most of the operating range.” However, some installations in the real world have proved  this assumption is not always accurate. 

A Sacramento Municipal Utility District study of an installation of lighting controls on one floor of a California office building produced interesting results. Dimming ballasts, motion sensors, and ambient light sensors were installed for more than 1,000 fixtures.  After the installations were complete, three different phases of control strategies, described in Table 3, were implemented in turn for evaluation of energy conservation.

Table 3. Control strategies

Table 3. Control strategies

The Phase 1 strategy in this study resulted in a peak electric demand reduction of 10.7 kW or 16 percent; this correlated to an estimated $7,130 cost savings per year. The Phase 3 strategy, showed a peak electric demand reduction of 20.9 kW or 32 percent; this correlated to an estimated $10,218 cost savings per year.  But it was the Phase 2 strategy that raised the most interest.

It was found that lowering the task tuning level of maximum output 10 percent from Phase 1 to Phase 2 increased overall energy savings by only 3 percent more than Phase 1, which was lower than expected.  Additional investigation into the Phase 2 results found that the lighting controls were not the culprit for the lackluster performance, but rather the fluorescent ballasts were to blame.

The ballasts used in the installation had a very unusual characteristic:  they consumed about 5 percent more energy operating at 70 percent of full output than they did when operating at 76 percent of full output.  This raised a number of questions about dimming ballast performance.

 

Dimming Ballasts

Also in 2013, Sacramento Municipal Utility District performed a study of dimming ballast performance characteristics for products compatible with 4 ft. T8 fluorescent lamps.  The goal was to study the most-used ballasts on the market to analyze energy reduction.

The ballasts studied had the following characteristics:

  • Full range continuous dimming
  • Four-wire controls (0-10 Vdc)
  • Compatible with 4 ft. T8 fluorescent lamps (25 Watt and 32 Watt)
  • Designed to operate 2 lamps and 3 lamps

Although trends of input signal to power consumption within the input control ranges of 20 to 70 percent are consistent with general expectations, the study identified some noteworthy findings.

  • Almost all products exhibited control deadbands where changes in control signal voltage resulted in no corresponding changes in light output or power consumption.
  • The deadbands tended to occur at the lowest settings (0-2 Vdc) and also at the highest settings (9-10 Vdc). 
  • Ballasts from one manufacturer exhibited a significant anomaly:  the power consumption at an input signal of 7 Vdc was substantially higher than with a control signal of 7.5 Vdc.  This manufacturer’s products also represented roughly one-third of the market options for products that met the study criteria.  

What these findings mean is that the expected energy savings from dimming ballasts may not always be achieved, especially if the light level selected falls within a product’s dead band or if a specified ballast’s power consumption is actually greater at a lower setting.

Moving Forward

When fluorescent dimming systems are designed to use strategies such as task tuning, occupancy sensing, daylight harvesting, or demand response, it is important to check manufacturer data and evaluate control input vs. power consumption.  To ensure energy savings are realized, lighting designers should also, include requirements for the performance characteristics of the dimming system in their specifications and review submittals.

Keep in mind that in addition to system types and equipment specifications, the energy savings of any lighting update may vary by usage and service provider. Also, the rebates and incentives to buy down the cost of the update may vary. 

Training Highlights

California utilities offer outstanding educational opportunities that focus on the design, construction and operation of energy-efficient buildings. Listed here are a few of the many upcoming classes and events; for complete schedules, visit each utility's website.

Lighting Retrofits A-Z
September 25 (9:00 am - 4:30 pm)
PEC - San Francisco

Basics of LED Technology
September 26 (8:30 am - 12:30 pm)
Frontier Project, Rancho Cucamonga

Attendees will gain a basic understanding of light-emitting diode (LED) technology, with an emphasis on benefits and limitations for real world applications. Come learn about the history, current status, and the future of LED technology which will help you make energy saving decisions.

 4 AIA/HSW Learning Units.

Basic Class:  Content is introductory in nature and requires no prerequisite knowledge or experience to grasp the concepts or participate in exercises.  Basic Educational activities and materials are meant to establish a foundation of knowledge and competence that will be expanded upon practice or in higher level seminars and workshops.

Introduction to Lighting
October 2 (8:30 AM - 12:30 PM)
Energy Education Center – Irwindale

This beginning level lighting seminar looks at ways to reduce energy usage and costs in your business through the proper selection of incandescent, fluorescent, and high-intensity discharge (HID) lighting systems. Improve your knowledge of light source technologies, performance characteristics, and their appropriate applications.

4 AIA/HSW Learning Units.  This is a Lighting Academy Class.

Reservations will be held 15 minutes following the start time above.  After this time your seat may be given to a waiting customer.

Basic Class: Content is introductory in nature and requires no prerequisite knowledge or experience to grasp the concepts or participate in exercises.  Basic Educational activities and materials are meant to establish a foundation of knowledge and competence that will be expanded upon practice or in higher level seminars and workshops.

California Advanced Lighting Controls Training Program (CALCTP) Systems - (2 Day Seminar)
October 7 & 8 (4:00 PM - 9:00 PM)
Energy Education Center – Irwindale

This two-day, 10-hour session for mid-managers (non-electricians) focuses on lighting controls functions and what environments are most conducive for their use. Participants must pass a final exam for certification. Successful completion of this course is a requirement for contractor certification.

All participants are required to complete approximately 10 hours of prerequisites prior to registering.

Below is the list of pre-reqs for the CALCTP classes.  The classes can be found at The Lighting Controls Association website.

  • EE101: Introduction to Lighting Control
  • EE102: Switching Control
  • EE103: Dimming Control
  • EE201: Daylight Harvesting

How to Register:

After completing all prerequisites, register by contacting The Energy Education Center – Irwindale registration desk at 800-336-2822 ext. 42537 or 626-812-7537.

You will need the name, job title, company name & address, phone number, and email address of the person(s) attending this course.

Note: Prerequisite certifications of completion will be required when registering.

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e-News is published by Energy Design Resources (www.energydesignresources.com), an online resource center for information on energy efficiency design practices in California.

Savings By Design (www.savingsbydesign.com) offers design assistance and incentives to design teams and building owners in California to encourage high-performance nonresidential building design and construction.

Energy Design Resources and Savings By Design are funded by California utility customers and administered by Pacific Gas and Electric Company, Sacramento Municipal Utility District, San Diego Gas and Electric, Southern California Edison and Southern California Gas Company, under the auspices of the California Public Utilities Commission.

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