Illuminating advances in wireless lighting controls

October 6, 2016

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Photo © Bigstock.com

By Craig DiLouie
Lighting controls are designed to support energy management and visual needs. They do so by ensuring the right amount of light is:

Like other electrical equipment, lighting controls are essentially input-output devices or systems. The input may be based on manual, time, occupancy, or light; the output may be switching or dimming. Using dimming, one can change colour output of light-emitting diodes (LEDs), creating new applications and markets. Lighting controls now offer the strong potential of producing data about lighting operation, such as energy and remote diagnostics useful for maintenance.

The most advanced lighting control systems feature 
three capabilities:

1. All applicable control strategies can be layered in a hierarchy of control zones.

2. The zoning can be precisely matched to the application, potentially resulting in a mix of larger and smaller areas (down to an individual luminaire). This increases responsiveness while allowing personal control of overhead general lighting.

3. There is programmability of functions and potentially a mechanism for measuring and monitoring.

Radio-frequency (RF) wireless communication is gaining traction as a facilitator of advanced lighting control in both new and existing buildings. This article presents recent research on the utility of wireless control, and then discusses its use in outdoor area lighting.

New research into wireless controls
A traditional lighting control design deploys manual switches and simple controls such as load scheduling to control large zones of luminaires. Even when occupancy sensors are installed, these devices are typically assigned to large 
control areas.

Increasingly stringent energy codes have made control zoning more granular. Emerging control strategies, such as daylight harvesting (i.e. daylight-responsive lighting) have become recognized based on proven effectiveness, resulting in a layering of strategies. Further, smaller control zones generally increase responsiveness, flexibility, and energy savings. However, individual luminaire control—with a lighting controller installed in each luminaire—increases the installed cost.

Wireless control signal communication can simplify installation while reducing material and labour costs associated with control wiring. This facilitates adoption of advanced lighting control by eliminating or otherwise reducing wiring installation. RF wireless controls originally gained popularity in the residential market, but have entered the commercial world after technological improvements and the development of wireless mesh network standards. It is a relatively young technology in commercial lighting control, with significant potential. This is made clear by a recent study from the United States that could have important implications for Canadian projects striving for energy efficiency.

The General Services Administration (GSA)—the U.S. agency responsible for federal real estate management and products and services procurement support—deployed advanced RF wireless control systems in two buildings. Lawrence Berkeley National Laboratory (LBNL), for the agency’s Green Proving Ground (GPG) program, sought to quantify the performance of these wireless lighting systems. (To download the LBNL report, visit www.gsa.gov/portal/mediaId/227615/fileName/Wireless_Advanced_Lighting_Controls_Retrofit_Demo_FINAL-508-062915.action[2].) Two California buildings were selected for installation—the 16-storey Appraisers Federal Building (San Francisco) and the eight-storey Moss Federal Building (Sacramento).

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Figure 1: Summary of pre- and post-retrofit average workday lighting power density at the Appraisers building and three sites at the Moss building.

The Appraisers Federal Building consisted mostly of open office spaces with some private offices and additional rooms. Occupancy sensors and manual switches were already installed before the study. The GPG study included a LED luminaire retrofit combined with wireless controls, and with one controller per luminaire allowing for individual control.

The Moss Federal Building also consisted mostly of open office spaces with some private offices, corridors, and meeting rooms. Each area already had manual switches or occupancy sensors, and in some cases, time scheduling systems. The GPG study saw installation of wireless controls with existing fluorescent luminaires in three locations on two floors, with multiple luminaires assigned to luminaire-based controllers.

At both locations, control software was used to assign luminaires to control zones, usually including four to six luminaires. Photosensors were installed in control locations configured within perimeter daylight areas; wireless occupancy sensors were installed, typically one per control location. In private offices, an occupancy sensor, dimmer-switch, and if the office had a window, a photosensor was installed. The system was then tied to an Internet server enabling facility operators to program and monitor the lighting using a web-based interface.

LBNL researchers studied each site before and after the retrofit, which included site visits, energy measuring, photometric study (i.e. light levels), and occupant satisfaction surveys. To form a baseline, a month of performance data was collected for luminaires in three control zones (one in Appraisers and two in Moss), estimating average lighting power density and annual energy consumption. Various lighting scenarios were then implemented and monitored to identify energy savings resulting from various control scenarios.

The advanced wireless lighting control (Figure 1) resulted in 32 per cent lighting energy savings at the Appraisers Federal Building, and the same for the three sites located in 
the Moss Federal Building.

Shedding light on the key findings
The lowest energy savings (i.e. nine per cent) at one of the Moss sites consisted of savings mostly produced by reducing after-hours operation of the lighting. Energy savings were dampened by programming that kept the luminaires at a dimmed 20 per cent level during periods of no occupancy, as opposed to previously being turned off by occupancy sensors. The highest energy savings were 42 and 47 per cent and located at the other two Moss sites; they were produced by a combination of after-hours lighting reduction, institutional tuning, and daylight dimming.

At Appraisers, the LED luminaire retrofit reduced lighting power density by 55 per cent, from 0.97 to 0.44 W/sf. Total energy savings, including the wireless controls, increased savings to about 69 per cent.

The LBNL researchers were able to disaggregate the performance of various control scenarios. In one of the Appraisers locations, occupancy sensors were implemented on about one-third of the luminaires. This was found to produce 22 per cent energy savings relative to a basic time-based control strategy, with an additional 10 for institutional tuning and seven for daylight harvesting. Ultimately, advanced wireless controls were estimated to save about 39 per cent lighting energy compared to time-scheduling control.

The researchers concluded implementing advanced wireless control systems can save significant lighting energy. It was noted savings are not guaranteed, as they depend on baseline control conditions (e.g. whether an existing system already has occupancy sensors installed and prevalence of daylight).

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Figure 2: Estimated project costs for retrofit and new construction scenarios involving advanced wireless lighting controls.
Image courtesy LBNL

At Appraisers, the LED lighting system with advanced wireless controls reduced average light levels from about 613 to 398 lx (57 to 37 fc), which was found to be satisfactory as it was above the 322 lux (30 fc) deemed appropriate for the tasks performed in the space. The occupant satisfaction surveys found inhabitants perceived the new lighting conditions and control performance favourably, with overall 
comfort increasing.

At Moss, average light levels remained fairly consistent before and after the upgrade. Occupant satisfaction was slightly reduced after the retrofit in terms of perception of comfort, light levels, and control performance. The researchers believed fluorescent lamp failures were the result of not being properly seasoned prior to dimming, coupled with commissioning errors and existing wired occupancy sensors applying legacy zoning onto new workstation and controls layouts. (NEMA Publishes LSD 23-2010, Recommended Practice: Lamp Seasoning for Fluorescent Dimming Systems.) Use of wireless occupancy sensors could have improved the control performance, as the sensors can be relocated easily without rewiring to better align with new workstation layouts.

In a retrofit situation, the project must carry the entire installed cost of the control system—however, if luminaires are replaced, installation labour can be economized. In a new construction scenario, return on investment (ROI) is based on the incremental cost of the new controls over an energy code-compliant solution (Figure 2).

LBNL researchers calculated payback ranging from three to six years. This suggests adding wireless advanced lighting controls to projects is a compelling opportunity in new construction and major renovation.

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Electrical professionals involved in the selection and delivery of lighting controls should stay educated on what is new to continue offering the best value to clients and the highest efficiency for buildings.

Outdoor lighting controls
While there are exciting advancements in wireless lighting controls for interior applications, outdoor controls are also undergoing a mini-revolution. Traditionally, outdoor lighting control was relatively simple. A typical scheme featured a controller providing an automatic on-off system based on time of day of an astronomical time switch or a photosensor. The luminaires were typically controlled at the circuit level with no individual luminaire control.

Commercial building energy codes imposing requirements for more advanced sequence of operations, coupled with greater controllability of LED lighting, have resulted in outdoor lighting control design becoming more sophisticated. While LEDs continue to displace other light sources in many applications (including outdoor lighting), they do not eliminate the need for control. Fortunately, intelligent multi-level control is well-suited to LED lighting due to the inherent controllability of the digital source.

Energy codes and outdoor lighting control
The American Society of Heating, Refrigerating, and Air-conditioning Engineers/Illuminating Engineering Society of North America (ASHRAE/IES) 90.1-2010, Energy Standard for Buildings Except Low-rise Residential Buildings, requires all outdoor lighting be controlled by a photosensor. Building façade and landscape lighting must be controlled by a time switch that turns the lights off at some point during the night.

The energy standard also requires all outdoor lighting power—other than building façade and landscape lighting, but including advertising signage—reduced by 30 per cent after normal business operations (based on schedule or occupancy).

Parking garage lighting power must be reduced by at least 30 per cent based on occupancy, with control zones limited to 334 m2 (3600 sf). Daylight harvesting and separate 
controls for day-transition areas (i.e. entrances and exits) must be implemented.

Created to save energy, these simple requirements have had a big impact on the world of outdoor lighting control, increasing demand for sensors, individual luminaire control, and controllability. This has increased demand for good design and commissioning.

While not all local codes have adopted requirements as stringent as ASHRAE/IES 90.1-2010, the products and experience developed around compliance provide ready-to-go solutions for both new construction and existing buildings.

Control options
A lowest-cost solution for outdoor lighting may include circuit-level, contactor-based switching of luminaires grouped in functionally appropriate control zones, each with its own schedule, or photosensors as needed. Therefore, the lighting would be controlled at a panel if the lighting is dimmable; control wiring must run the luminaires.

A better solution might include luminaires with attached control devices providing individual multi-level-occupancy- and daylight-based luminaire control. The photosensor activates the lighting, while the occupancy sensor raises lower light output and electrical input based on occupancy. For example, in a parking lot, this solution would be appropriate for area lighting, while signage and security lighting could be operated during dusk and dawn using a photosensor or a limited time of night that is based on a schedule.

The most advanced solution in terms of capabilities is an integrated wireless control system that provides an on/off mechanism and dimming implementing daylight-, occupancy-, and time-based strategies. In a parking lot, the area lighting could be zoned and controlled as individual luminaires or groups, while the signage lighting could be controlled on a schedule and security lighting dimmed as individual luminaires or groups.

Occupancy-based multi-level outdoor lighting control is a relatively new phenomenon. Options are generally limited to passive-infrared (PIR) detection. These options may expand in the future to include options for digital imaging (i.e. non-recording video), which offers more precise detection in the dynamic outdoor environment.

Wireless lighting control for outside
Again, wireless control demand and technology continues to advance at a rapid rate due to its advantages of allowing devices to communicate without costly installation of wiring. It provides further advantages of two-way communication and individual luminaire control.

Two-way communication creates two distinct capabilities. Operators can recalibrate the system, change schedules, and distribute commands from a central point. Many wireless control solutions incorporate intelligence enabling the capture of performance data, which can be reported to a central point for maintenance, performance, and security purposes. Systems such as these are supported by a web-based interface, enabling operators to remotely visualize real-time performance, set schedules, zone luminaires in groups, and generate custom reports optimizing management of outdoor lighting as an asset. Some offer GPS-location capabilities, allowing operators to understand what is happening at each control point and where that point is—this can be highly useful for maintenance of street, public space, and large area lighting.

Whether the lighting control application is wireless devices inside or use outdoors, selecting the optimal solution involves evaluating necessary control sequence of operations, need for multi-level control, configurability, and data for predictive maintenance, energy analysis, and security. The selected control solution should be able to deliver the desired feature set.

During decision-making, one should consider outdoor lighting controls not in isolation, but rather as part of the total building lighting control system. With the integration of luminaires and controls, the traditional view of these as two separate items is changing to one. In existing building lighting upgrades, controls should be considered as part of a lighting and control solution supported by utility rebates recognizing controls as well as lighting.

Conclusion
With intelligence, communication and the ability to collect data, today’s lighting can be viewed as systems delivering sensing, decision-making, control, and prediction. Electrical professionals involved in the selection and delivery of lighting controls should stay educated on what is new and how it works to continue offering the best value to clients.

craig_dilouieCraig DiLouie, a lighting industry journalist, educator, and marketing consultant, is principal of Calgary-based ZING Communications. He is the education director for the Lighting Controls Association. DiLouie can be contacted via e-mail at cdilouie@zinginc.com[4].

Endnotes:
  1. www.lightcontrolsassociation.org: http://www.lightcontrolsassociation.org
  2. www.gsa.gov/portal/mediaId/227615/fileName/Wireless_Advanced_Lighting_Controls_Retrofit_Demo_FINAL-508-062915.action: http://www.gsa.gov/portal/mediaId/227615/fileName/Wireless_Advanced_Lighting_Controls_Retrofit_Demo_FINAL-508-062915.action
  3. [Image]: http://www.constructioncanada.net/wp-content/uploads/2016/10/Lighting_Controls_18.jpg
  4. cdilouie@zinginc.com: mailto:cdilouie@zinginc.com

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