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 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.

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.

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.