When Less Is More: ECs Have Much to Gain From Wireless Power

Wireless Photo Credit: Shutterstock / Macrovector
Photo Credit: Shutterstock / Macrovector
Published On
Mar 15, 2019

Wireless technology takes on a new meaning with the latest generation of lighting controls hitting the market. While the term “wireless” has generally referred to cable-free digital communication, it also describes how these devices are powered. Eschewing even batteries, the newest switches and sensors can harvest energy from friction, light and temperature differences.

These self-powered controls offer numerous advantages for building owners, especially in retrofit installations. With no hardwiring required, the devices can be placed anywhere, and some can even be mounted using only adhesive tape. While similarly independent battery-powered products have been on the market for some time, replacing those batteries can add to a facility team’s maintenance chores as well as hazardous landfills. These new devices offer a set-and-forget solution until a space is reconfigured. Then they can be moved easily to better serve the redesigned space.

While some electrical contractors could feel threatened by these wire-free products, manufacturers suggest that need not be the case. By pairing their existing lighting-controls expertise with the capabilities of self-powered sensors and switches, ECs could broaden their business into the schools, offices and industrial facilities where the devices are expected to have the biggest impact.

Truly wireless networking

The biggest value proposition for any networked lighting control system is energy savings, and a recent report by the DesignLights Consortium (DLC) makes clear the possible significance of those savings. The DLC sets the standards and oversees certification for lighting products that are eligible for electric utility energy-efficiency rebates. Its September 2017 report, “Energy Savings from Networked Lighting Control Systems,” documents energy savings from networked control systems averaging 47 percent across 114 surveyed buildings. Some building types nearly doubled those savings when they added networked controls—warehouses in the study cut lighting-related energy demand by 75–88 percent.

With these savings in mind, some form of networking is almost a given in new commercial/industrial/institutional (CII) construction. Wiring such systems into place adds incremental expense, which can be quickly recouped in lower electricity bills. Retrofitting a networked system of wired sensors and switches into an existing lighting system can be a more expensive proposition, however. This is especially true for older buildings, such as schools, where a wiring project could require abatement procedures for asbestos or lead paint.

Controls manufacturers have pursued several network-communication technologies to address retrofit concerns and to help future-proof new-construction installations. Wi-Fi is popular for home automation, since the required router has become a commodity appliance in any home with a broadband connection. However, Wi-Fi’s higher power demand almost always requires connected devices to be fully wired. Bluetooth and Zigbee both allow router-free operation and significantly reduced power demand, enabling the use of battery-powered—and, now, battery-free—sensors and switches. Zigbee protocols initially provided users a range advantages over Bluetooth operations, because of a mesh design that turned every device on the network into a signal repeater. However, Bluetooth has developed its own Bluetooth Mesh protocol to match Zigbee’s capabilities.

As protocol developers have kept themselves busy powering down their technologies’ energy requirements, device developers have been working toward a similar goal with lighting controls. German manufacturer EnOcean, formerly a division of Siemens, has led these efforts for almost two decades. Its energy-harvesting switches and sensors have been incorporated into products from leading lighting-controls companies, including Hubbell Lighting, Thomas Research Products and WattStopper.

By simplifying communication requirements, EnOcean’s sensors and switches operate on minuscule amounts of energy, harvested in one of three methods:

  • Kinetic energy generated by movement-related friction. Also called piezoelectricity, this is the same concept used in the electronic ignition systems for burners on residential gas ranges. The simple act of flipping or tapping on a light switch can generate all the energy required to control a connected luminaire to turn on or off.
  • Solar energy, drawing from even low levels of ambient light. This is the same technology powering inexpensive solar calculators.
  • Temperature differences, using thermoelectric principles. If you have a wood stove, you might also have a similarly powered stovetop fan to help move heat around your home.

Troy Davis, EnOcean’s U.S.-based sales director, sees the current transition to LED lighting—what he calls “LEDification”—as a great opportunity for adding to the energy savings a shift to LEDs from fluorescent and HID fixtures and lamps already provides.

“You can parachute into an existing building pretty easily [during such upgrades],” he said.

Hooking owners, especially those with large facilities, on the advantages of going battery-free isn’t a difficult sell.

“We’ve heard that it’s anywhere from $86 to $112 to roll a truck to replace a battery,” he said. “If you’re on the 14th floor of an office building and you’ve got a technician billing out at $86 per hour, there’s a real argument for no battery or an extremely long-lasting battery that lasts 10 years or more.”

One company promoting such retrofit solutions is Fulham Co., a Hawthorne, Calif., lighting and controls manufacturer. At LightFair 2018, Fulham introduced a new Bluetooth Bridge LED controller that can be installed in any electrical box or fixture wired for 0-10V dimming. Employing Bluetooth mesh technology, the bridge adds wireless dimming control using a mobile app or an EnOcean-enabled switch.

“Each bridge can support up to 600 watts of luminaires,” said Alvaro Garcia, Fulham’s senior director of product management.

This means a single bridge could serve a daisy-chained collection of ceiling troffers in a classroom or conference room. He added that the bridge could then be easily paired with an EnOcean-powered wireless switch.

“It essentially replaces a 0–10V wall switch,” he said.

New energy codes are driving the market for wireless solutions. The latest editions of the California Energy Commission’s Title 24 energy code and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 90.1 both incorporate requirements for daylight and occupancy sensing to automate fixture operations when spaces are unoccupied or daylight levels are high. The bridge also supports device-level power metering, which also can aid energy code compliance.

“Our initial targets are small offices trying to meet Title 24 or ASHRAE compliance,” Garcia said. “It’s an easy, contractor-friendly way to retrofit an office.”

Bringing multiple protocols together

EnOcean isn’t alone in developing communications protocols for low-powered, wires-free devices. The Zigbee Alliance, the nonprofit group behind the Zigbee and Zigbee Pro wireless communications embedded into numerous smart-home thermostats, door locks and light bulbs, has developed its own wireless Zigbee Green Power specification to address this new market. This protocol allows Green Power switches to control existing Zigbee Pro-certified lamps and fixtures, bringing new capabilities to those products, which previously could only be controlled through mobile apps.

A major difference between EnOcean and Zigbee Green Power approaches had been the radio frequency used for communications between sensors, controllers and controlled devices. EnOcean, which is heavily invested in the European market, uses a proprietary protocol that functions on any of a range of sub-gigahertz (GHz) frequencies, depending on the installation’s region. Zigbee Green Power, like the primary Zigbee specification, specifies operation at 2.4 GHz, regardless of region.

However, because EnOcean has had such a head-start in energy-harvesting technology, the company has locked up a number of valuable patents critical to battery-free operation. To capitalize on this market- leading position, the company has begun offering original equipment manufacturers products capable of operating at Zigbee’s preferred 2.4 GHz. This move has expanded EnOcean’s presence in the U.S. residential market. The company now is participating in the Friends of Hue partnership program established by Signify (the company formerly known as Philips Lighting) to broaden the adoption of its wireless Hue lighting products.

As attractive as the residential market might eventually become, Zigbee Green Power’s developers agree with EnOcean’s Davis that the CII market offers the greatest immediate opportunities for wireless, battery-free controls. Victor Berrios, the Zigbee Alliance’s vice president for technology, echoes Davis in his description of the problem such products can solve for building owners and managers.

“If I have to change 10 batteries over the course of three to five years, that’s not much, but if every month, I have to go through and change 1,000 batteries, then it becomes a real economic argument,” he said.

Broader CII adoption could mean less-expensive residential devices.

“As with many other things, that’s going to drive economies of scale and drive costs down,” he said.

Of course, not every application is well-suited to an energy-harvesting approach. The power limitations of these switches and sensors also limit the amount of data they can transmit. The simple on/off or dimming information a light switch needs to transmit falls well within the capabilities of a self-powered device. Sensors, however, can present data-transmission requirements that only wired connection can meet.

“When you start talking about sensors, it may depend on the frequency of the data,” Berrios said. “You have to look at the use case for the particular product.”

He compared the relatively infrequent operation of an out-of-bounds sensor to the more demanding requirements of a sensor that operates continuously.

Opportunity for ECs

It’s possible that not every EC is going to be a fan of a technology designed to eliminate the need for electrical wiring. EnOcean’s Davis has seen a range of reaction in the electricians he has met while leading training programs with various local unions of the IBEW. Some contractors see the technology as nothing but a threat, while others are enthusiastic to learn more about new ways to help customers solve problems. He tries to impress upon these audiences the way stricter energy codes are driving new opportunities for electrical pros, regardless of how much wiring is involved.

“In California, they can’t find enough electricians to keep these projects rolling,” Davis said. “In all honesty, we’re trying to add more work for the electrical contractors. It’s been great to see the electricians who jump in and make it work, and they are the ones who get the next job.”

About the Author

Chuck Ross

Freelance Writer

Chuck Ross has covered building and energy technologies and electric-utility business issues for a range of industry publications and websites for more than 25 years. Contact him at chuck@chuck-ross.com.

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