LED High-Bay with Wireless Control
Warehouse Lighting: Wirelessly Occupancy Controlled LED vs. Uncontrolled HID
High-bay LED fixtures with a wireless occupancy control system.
Item ID: 279
Technical Advisory Group: 2012 LED Lighting TAG (#5)
Technical Advisory Group: 2013 Advanced Lighting Controls Systems TAG (#7)
Typically, high-intensity discharge (HID) and fluorescent sources are used in conventional high-bay lighting applications. However, high-bay luminaires using LED light sources are becoming more widely accepted. Factors that support their adoption in warehouse and other high-bay applications include reduced maintenance, long life, controllability and directional control of the light. Wireless technology makes retrofits affordable; retrofits had previously been considered prohibitively expensive due to new wiring costs. But integrated, system-wide wireless controls can provide maximum operational flexibility and energy savings. Depending on the equipment being replaced by the new system, energy savings can range from 50% to 90%.
High-bay lighting employing LED technology are widely available from a number of manufacturers, and automatic controls (e.g., ZigBee-based) are becoming more prevalent. The U.S. Department of Energy (DOE) is encouraging research, development and market penetration of the technology, and is providing resources for researchers to provide objective, ongoing information about the technology. The DesignLights Consortium includes a category for LED high-bay and low-bay lighting and over 600 products qualified as of April 2013.
LEDs are particularly well suited to operate with automatic controls such as occupancy sensors and demand response systems, which reduce light output and power consumption during periods of low occupancy. This technology also works well in daylighting applications. Lamp life could be significantly longer than metal halide and high-pressure sodium systems, making LEDs especially beneficial in hard-to-access locations. The DOE predicts that LED lighting will continue to improve in efficacy and significantly decline in price.
Baseline Description: 400W Metal Halide without controls, 12/7 operating time
Baseline Energy Use: 2006 kWh per year per unit
This assumes that each unit has 458 input watts (lamp plus ballast) operating 12/7/365.
Manufacturer's Energy Savings Claims:
"Typical" Savings: 70%
Savings Range: From 25% to 95%
One example fixture by Digital Lumens is 180W and 8000 lumens, designed to replace a 400W HPS fixture. Without controls, this system is expected to deliver 55% savings; with wireless controls, this system may achieve over 90% savings. For comparable wirelessly controlled T5 high-bay systems with motion sensors, savings were demonstrated in the 25% to 60% range when compared to metal halide technology (Albeo, 2013). If the motion sensor control savings observed in previous case studies are applied to the Digital Lumens product, it is anticipated that savings of 65% to 70% would be achieved. Higher savings might be achieved with the addition of daylight harvesting/continuous dimming capabilities.
The low range number accounts for applications where either occupancy is not highly variable or lights were being manually controlled to avoid overuse already.
Digital Lumens products come with occupancy and daylight sensor and controls standard, as well as their Intelligent Lighting System which provides reports on energy use, ocupancy rates and more and have verified savings of 92% in a warehouse retrofit formerly using 1000W metal halide.
Best Estimate of Energy Savings:
"Typical" Savings: 74%
Low and High Energy Savings: 35% to 95%
Energy Savings Reliability: 6 - Approved Measure
160W LED, 4228 hr= 702kWh/yr, 65% less than MH base case. Switching to LED sources for highbay warehouse lighting saves around 65% of energy use, after that the occupancy patterns and how well tuned the occupancy and, if used, daylight sensors are and what the actual occupancy is. The Digital Lumens product has software to measure the energy use, occupancy rates and more. A utility did it's own study based on energy consumption at the meter and verified the savings in the case study on the Silver Beauty warehouse.
One of the biggest variables in this system is the controls. The savings achieved by the controls will depend largely on how frequently a typical aisle in the lit space is occupied. A very busy warehouse may not gain much additional savings with motion sensor controls because the lights will be on nearly all the time; in contrast, a warehouse that has areas that are seldom used (more typical) will save more energy because the lights will dim when these areas are not occupied. A Lighting Research Center study in 2008 found that motion sensor controls were responsible for an additional 25% energy savings above the energy savings for the high-efficiency luminaires installed in the study (Gutierrez, 2004). This increases 65% energy savings to 74%.
High-bay wireless occupancy controls is a deemed measure in the BPA C and I Lighting Calculator spreadsheet. Although the standard energy savings attributed by BPA to this measure is less than what is suggested here, the technology has been embraced by BPA as valid and therefore energy savings reliability (ESR) is 6.
Energy Use of Emerging Technology:
521.6 kWh per unit per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
The systems are new and manufacturer's produce most of the case studies found. ComEd in Chicago did a verification study of an installation of Digital Lumens 1000W MH equivalent LED and with their metering data verified the intelligent software which is part of the Digital Lumens product. Manufactures size LED systems at about half the wattage of traditional HID, and U.S. DOE SSL program also does in Adoption of Light-emitting Diodes in Common Applications, Apr 2013, but as LEDs keep improving that is a shrinking number. The the controls add to that based on the occupancy and daylight harvesting in a specific application. Controls are usually credited with about 30% generic savings and more are possible, so are less. If occupants were careful with lights prior to adding controls it is possible to show negative savings due to setback times if occupants get lazy.A study with only three samples (Williams, Jan 2012) showed occupancy and daylight harvesting combined to save 63%
Potential number of units replaced by this technology:
Indoor HID lamps. 2010 U.S. Lighting Market Characterization, Navigant for U.S. DOE, 2012, Table 4-1: “Estimated Inventory of Lamps in the U.S. by End-Use Sector in 2010”
Note: there are 69,388,000 MH lamps in the U.S. (in 2010), with 29,514,000 being in outdoor locations. The indoor population is thus 39,874,000. Prorating the U.S. lamp population by percentage of the U.S. human population that resides in the Northwest yields a total of about 0.04 x 39,874,000 = 1,594,960 lamps.
Regional Technical Potential:
2.37 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Installed first cost per: unit
Emerging Technology Unit Cost (Equipment Only): $865.00
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $920.00
Baseline Technology Unit Cost (Equipment Only): $538.00
$268 PSMH ProLighting.com website, install 2.7 hrs (RS Means) @ $100 hr (CED)
Remove old ballast $50, recycle MH lamp $5,
new LED $550-650 plus 30% profit is $715, (personal contact Digital Lumens, install 1.5 hrs (if 2 electricians are used), plus about 15 minutes to program controls from laptop on ground.
According to Digital Lumens, a single 180W, 8000 lumen fixture costs $1,250, including installation and controls. Energy use is estimated at 554 kWh per year, based on 180W usage for 3,100 hours per year. An additional 25% energy savings could result from wireless motion sensor controls. This represents a 66% energy savings over a 400W metal halide system operating 3,100 hours per year.
Simple payback, new construction (years): 2.4
Simple payback, retrofit (years): 13.4
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
Daintree Networks provides a "sample" simple payback calculation for a 64,000 square foot warehouse equipped with their wireless controlled high-bay LED technology. In this example, energy savings were 63% over the baseline, with a project total up-front cost of $42,048 and a simple payback of 2.4 years with a $0.12/kWh tariff. Assuming Northwest rates of $.09/kWh, the simple payback for this installation would likely be about three years, though it is difficult to convert exactly because it is unclear how much, if any, Daintree was counting for maintenance savings. The energy savings asserted by Daintree Networks and other manufacturers seem reasonable, given that similar systems employing high efficiency T5 fluorescents with wireless motion controls have been studied by the Lighting Research Center and were found to provide energy savings of between 23% and 58% (Gutierrez, 2004).
A Digital Lumens 180W high-bay LED luminaire was priced at $1,250 per fixture; in comparison, the baseline cost of a metal halide fixture was $140. Given an estimated 66% energy savings and a $.09/kWh electric rate, and with no assumed O&M difference between the two fixtures, the simple payback on a retrofit is estimated to be 11.5 years. Simple payback on new construction is estimated to be 10.2 years. In reality, there would be some additional O&M savings for the LEDs versus the metal halides so payback would likely be faster than indicated by these figures.
Lighting is one of the largest sources of energy consumption in U.S. commercial buildings, accounting for more than 35% of an average building's electricity use. High-bay commercial settings, such as warehouses, often use an even higher percentage of their overall electricity consumption for lighting, due to the challenges of high-bay lighting geometry, and because many warehouse spaces are semi- or unconditioned spaces, reducing HVAC energy usage. Most commercial warehouses also experience high variability in their occupancy, and thus would benefit from an “intelligent” lighting system capable of dimming or turning off fixtures based upon sensor inputs on ambient light levels (daylight harvesting) and occupancy (Draintree Networks, 2011).
High-bay applications often make the installation of a wired control system – either a wired overlay or a wired direct current (DC) power/control system – difficult and expensive. A wirelessly controlled overlay system may be the least expensive option for these applications (Draintree Networks, 2011). Multiple manufacturers provide wireless overlay LED systems, including Daintree Networks, Digital Lumens and Lutron Electronics. Several manufacturers, including Daintree Networks, are using the ZigBee communications protocol for their control networks (Draintree Networks, 2011)(Adura Technologies, 2013). Others, such as Lutron Electronics, use proprietary communications protocols (Lutron Electronics, 2013). These wireless controls are being paired with LED lighting technology to produce a highly controllable, efficient and long-lasting solution for high-bay lighting applications.
LEDs offer several advantages over incumbent technologies:
LEDs are anticipated to have an exceptionally long lifespan; up to 20 years is estimated for some of the fixtures being produced today. This long lifespan means that in high-bay applications where fixtures are difficult and costly to access, maintenance cost savings can be significant.
- LEDs produce a large amount of visible light for the amount of electric power they consume compared to most other technologies, and their efficiency is anticipated to improve in the decades to come (EERE, 2012).
- LED light output is highly directional, meaning that more of the emitted light reaches the illuminated surface rather than being lost in other directions (EERE, 2012), further increasing the efficiency with which LEDs can perform lighting tasks, particularly in high-bay applications.
- LEDs can be continuously dimmed without loss of efficiency or reduced lamp lifespan. In fact, LEDs run cooler when they are dimmed, and this may actually increase their service life because one of the main factors that affects lifespan is high temperature.
- LEDs are well suited to being paired with digital controls, such as ambient light or occupancy sensors, in order to dim or switch off the lights when their full output is not needed.
But for all of their advantages, LEDs suffer from high costs and lack of deployment experience. As costs continue to come down and this technology becomes more common, both issues are being addressed, and it is anticipated that the majority of commercial lighting will be provided by LED fixtures (EERE, 2012) in the future. Currently there are nearly 600 LED fixtures listed in the DesignLights Consortium qualified product list under the high-bay commercial and industrial category, up from only 200 in 2011 ( DLC, 01/01/2013). It is expected that both the quality and the availability of products will continue to increase in the near future.
The DOE has tested and confirmed that some LED luminaires currently on the market are suitable for high-bay applications and meet the solid state lighting program criteria of efficiency and light output for this application (EERE, 2011). Additional LED products that meet and exceed both efficacy and light output requirements for high-bay applications are expected to be available soon. Most of the highest efficiency LED lamps produce light in the blue-white range with a color rendition index (CRI) of around 70. This color is not appropriate for most retail environments, but is suitable for industrial or warehouse settings (EERE, 2011). Additionally, manufacturers are now providing fixtures that are environmentally sealed to protect against moisture intrusion, specifically designed for manufacturing environments subject to regular wash-down cleanings (Digital Lumens, 2011).
Wireless controls paired with LED fixtures offer many advantages in a high-bay setting. Vendors have indicated that energy savings of up to 90% compared to the original lighting system have been achieved using this combination of technologies ( Jordan, 2002 Pg 185-193). Additionally, vendors indicate that a wireless “intelligent” lighting system provides savings 40-70% higher than a system that uses LEDs alone without such controls (Draintree Networks, 2011). As in all such technologies, use caution when relying on energy savings estimates over a baseline for incumbent technologies such as out-of-date and highly inefficient linear fluorescents that do not have control measures.
This proposed emerging technology is a hybrid of both a lighting technology (LED) and a control strategy (wireless overlay). As such, each component of this hybrid could conceivably be changed for a different one, and comparisons should be made not only against the in situ baseline technology, but also against alternative replacement technologies such as linear fluorescents with wireless controls, or LEDs with wired DC power/controls. T5 fluorescent luminaires with wireless controls have demonstrated levels of energy savings comparable to LEDs with wireless controls (as of December 2008 (Gutierrez, 2004 Pg 1865-1869)). HID lamps are also increasing in efficiency and controllability (Albeo, 2013). Only by comparing outcomes with other modern lighting solutions can a true determination of energy savings and cost effectiveness be made, and this will vary highly depending on the specific application.
Standard high-bay lighting uses no controls with high-pressure sodium (HPS) or metal halide lighting. Fluorescent lighting is becoming increasingly common in high-bay applications.
This technology is available through multiple vendors. Nearly 600 LED fixtures are currently listed in the DesignLights Consortium qualified products list under the high-bay commercial and industrial category (up from only 200 in 2011 (DLC, 2013)).
Wireless Local Area Networks (WLANs) have developed rapidly with the advent and popularization of cellular technology. Advances intended for the cellular market eventually led to local data networks created for in-home connection of personal computers, printers and other devices (Jordan, 2002). Rapid decreases in price allowed an ever-increasing array of devices to be networked into a wireless system.
The IEEE 802.15.4 standard was issued in 2003 specifically to support the adaptation of low-rate wireless networks in the building automation sector, with the hope that such wireless networks would avoid much of the expense associated with wired sensor and control systems (Gutierrez, 2004). Wireless networks, originally designed purely for data transmission purposes, soon were integrated into control systems for a variety of devices, including lighting systems.
The long life and low maintenance requirements of LEDs are particularly beneficial in high-bay applications, where it is difficult to access light fixtures for bulb replacement. The low failure rate of LEDs, combined with the fact that their failures are characterized by a slow diminishing of light output over time rather than catastrophic failure, means that maintenance costs are significantly reduced. Since LEDs typically "fail" by simply reducing light output over time, this allows for scheduled group relamping, which can save time and money because staff do not have to replace each lamp or fixture as it fails, as is the case with most other technologies.
End User Drawbacks:
The main barriers to LED deployment, with or without intelligent controls, are their high costs and uncertain lifespans. Most manufacturers indicate that LEDs will have exceptionally long lifespans (some suggest 100,000 hours or more). However, LEDs have not yet been in the field long enough to definitively verify their longevity. In addition, while LED systems can provide significant energy savings, the first costs of the system can be prohibitive. As LED technologies continue to improve in both efficiency and in cost, applications will become more economically feasible.
Operations and Maintenance Costs:
Maintenance on the actual LEDs is expected to be virtually zero over the lifetime of the product. However, the onboard drivers may need replacement long before the LEDs themselves dim to the point of needing replacement. O&M costs are difficult to assess with certainty, due to the limited long-term deployment experience for this technology.
Controls are usually estimated as having a useful service life of 15 years.
LEDs rated at 50,000 hours that are used between 2,000 and 3,000 hours per year should also last about 15 years. Increasingly life for LEDs is listed as 100,000 hours.
The main competing technology is wirelessly controlled, high-efficiency, linear fluorescents with similar dimming and occupancy-sensing capabilities. Ceramic metal halide with electronic ballasts is also gaining ground in this area.
Reference and Citations:
Albeo LED: C-Series High Bay
Describes cold warehouse retrofit from 400W MH to LED with occupancy controls.
Lighting Controls in Commercial Buildings
Only included three warehouses but its a start.
Adoption of Light-Emitting Diodes in Common Applications
Department of Energy, Solid State Lighting Program, Building Technologies Office
Includes information on installed base, potential savings, and more. Attributes savings to combination of efficacy of fixtures and controls.
DOE Solid-State Lighting CALiPER Program, Summary of Results: Round 13 of Product Testing
Department of Energy, Energy Efficiency & Renewable Energy
Digital Lumens Unveils Major Expansion of Most Energy-Efficient Intelligent LED Lighting System on the Market
Solid State Lighting
U.S. Department of Energy, Energy Efficiency & Renewable Energy
LED Lighting Facts
U.S. Department of Energy
Wireless Lighting Control Solutions for: Warehouse and High Bay
Daintree Networks, Inc.
Albeo LED Warehouse Lighting
Zamos, et. al.,
Adaptive Lighting Controls Panel
U.S. Department of Energy, Municipal Solid-State Street Lighting Consortium
Lighting Controls Association
Lighting Controls Association
The site has good information on all sorts of controls but may require membership to access much of it.
Search engine is a good tool to access information about products and some articles
Hubbell Building Automation
Wireless Lighting Control FAQs
Lutron Components Make Light Control Integration & Connectivity Easy
Lutron Electronics Co., Inc
Wireless communications and networking: an overview
IEEE Antennas and Propagation Magazine
Adura Wireless Lighting Control
Field Test DELTA, T5 Fluorescent High-Bay Luminarires and Wireless Lighting Controls
Lighting Research Center
Energy Savings Potential of Solid-State Lighting in General Illumination Applications
Navigant Consulting, Inc.
DesignLights Consortium Qualified Products List
DesignLights Consortium, Northeast Energy Efficiency Partnerships, Inc.
On the use of IEEE 802.15. 4 to enable wireless sensor networks in building automation
Personal, Indoor and Mobile Radio Communications
US DOE Solid State Lighting Technical Resources