No batteries or line power, no problem: Energy harvesting technology empowers innovative wireless designs

February 1, 2012 OpenSystems Media

3Using batteries or line power to run energy management systems in buildings entails several
disadvantages regarding difficult and costly installation. Energy harvesting systems based on the
EnOcean wireless standard offer the “install and forget” reliability of wired technology with the
flexibility of wireless technology. Devices can now power themselves without batteries or line
power, therefore providing more flexibility than wires and less maintenance cost than batteries.

Building control systems have traditionally employed miles of wires connecting the sensors and switches needed to monitor the environment within buildings. Battery-powered devices were sometimes added for hard-to-wire locations, especially in retrofit situations. However, the costs associated with battery replacement and disposal prohibited widespread market acceptance.

The EnOcean wireless standard overcomes many of the installation barriers that have stood in the way of making buildings more energy efficient. Building automation products such as sensors, switches, and controllers based on the EnOcean wireless protocol are not only interoperable with each other regardless of the manufacturer, they are also interoperable with other communication protocols such as TCP/IP. The maturation and convergence of the EnOcean and TCP/IP communication protocols have led to a dramatic increase in the number of energy management options available to integrators.

Limitless supplies of energy

Self-powered wireless sensors and switches implement energy harvesting technologies. The concept of harvesting energy from the environment is not new; wind and water have been sources of energy for hundreds of years. However, the concept of making a wireless and battery-less system has only recently been achievable.

The EnOcean energy harvesting model stems from a simple observation: Where building sensor data resides, sufficient ambient energy exists to power sensors and radio communications. Harvestable energy sources include motion, indoor light, and temperature differentials. These rudimentary sources provide enough energy to transmit and receive radio signals between controls and sustain vital communications within an energy management system. Instead of batteries, EnOcean-based controls use miniaturized energy converters to supply power to building energy management devices.

Harvesting motion, indoor light, and temperature differences

Three types of energy harvesting techniques are optimized for use in today’s buildings (see Figure 1):

  • Kinetic: Harvesting energy from motion
  • Solar: Harvesting energy from indoor light
  • Thermoelectric: Harvesting energy from differences in temperature

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Figure 1: Energy harvesting modules draw energy from sources including motion, indoor light, and temperature differentials to transmit and receive radio signals between controls.

Implementing a wireless energy harvesting system

Building Automation Systems (BAS) reduce energy consumption in buildings on average 40 percent when smart sensors and controls are in place. However, most buildings still do not contain the controls necessary for managing energy, nor do they contain the cabling infrastructure needed to connect the essential sensors and controls. While widespread BAS integration has been hindered by several factors, self-powered wireless controls have overcome major hurdles, including:

  • Expenses required for retrofitting existing buildings (installation costs, slow payback, complicated installations)
  • Limited interoperability among devices
  • Limited interoperability among communication protocols

These classic barriers have been overcome by wireless controls that power themselves using energy infinitely available in office building spaces.

Faster installations = faster paybacks

Wired devices are generally less expensive to purchase than wireless devices. However, installing wired systems, particularly in retrofit scenarios, entails considerably more labor and materials than it does for installing wireless systems. In a conventional wired installation, the process involves pulling miles of wire for sensors, switches, and controllers. Obstacles such as asbestos and impassable materials are frequently encountered when fishing wires through walls and ceilings. Additionally, wired retrofit installations can disrupt business operations and force building closures. Wired installations often require patching and repainting, which increase the amount of time and labor costs required for the installation.

Interoperability among devices

The EnOcean Alliance has created an ecosystem around energy harvesting wireless technology to develop an industry standard, continue product interoperability, and promote the technology among members. Interoperability of different end products based on EnOcean technology is an important success factor for establishing the technology in the market. For this reason, the EnOcean Alliance standardizes communication profiles, ensuring that sensors from one manufacturer can communicate with receiver gateways of another, for example.

Integrators and end users thus have the entire product portfolio at their disposal to meet their unique needs. Product manufacturers can focus on their own special field while contributing their particular niche to the market. Profiles of existing and upcoming types of equipment are defined in EnOcean Equipment Profiles. Visit the EnOcean Alliance website at www.enocean-alliance.com for more information on application-specific profiles.

EnOcean wireless technology is already established in building systems through standardized sensor profiles. A portfolio of more than 800 products creates interoperability among the different operating facets of a building. Worldwide implementation of EnOcean technology in hundreds of thousands of buildings has made it an industry standard.

Interoperability among communication protocols

Internet Protocol (IP) has now become a worldwide standard for over-the-Internet data communication among devices. One idea currently being discussed involves assigning every outlet and every filament lamp its own IP address and then connecting them over the Internet. What many do not know is that all electric loads today already can be addressed over an IP network enabled by battery-less wireless technology and matching access points.

Leveraging the strengths of both technologies will create long-term value by allowing the existing wired or wireless TCP/IP infrastructures to seamlessly add wireless devices for additional functionality and greater energy savings. As a practical, wireless extension of TCP/IP systems, EnOcean technology can lower cost of ownership in retrofits and new buildings. Many facilities have successfully deployed wireless systems in which EnOcean and TCP/IP technologies are interoperating to reduce installation and maintenance costs, along with providing energy savings beyond 30 percent.

EnOcean technology in action

Hotels are notoriously difficult to wire, and thus provide an ideal habitat for implementing energy harvesting wireless controls. For example, in lieu of ceiling lights, floor and table lamps are most commonly used for lighting since ceiling access is extremely limited. However, most hotel rooms are now fitted with TCP/IP and Ethernet or Wi-Fi connections.

This is an example where energy harvesting wireless controls truly shine. The self-powered controls can be installed without access to line power. The sensors can feed sensor data such as occupancy status into a TCP/IP backbone and allow the hotel’s lighting and HVAC control system to make smart decisions regarding energy usage and management. Furthermore, the energy management controls can be installed in hotel rooms in between guest stays, which is unheard of when strictly using wired controls.

Because hotel rooms are so often left unoccupied, they represent great potential for conserving energy. As illustrated in Figure 2, a hotel room energy system can use occupancy status data provided by the wireless controls to turn off lights and TVs, as well as change temperature set points to stop heating or cooling unoccupied rooms.

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Figure 2: Energy harvesting wireless controls can enable a hotel’s lighting and HVAC control system to make smart energy management decisions.

These simple forms of lighting and HVAC control are low-hanging fruit in terms of energy conservation. As technology has made BAS easy to install, hotel owners can begin recouping dollars lost to energy mismanagement. An access point can receive data from wireless controls, then feed the system the information it needs to make smart decisions regarding energy management. When a guest enters a hotel room and inserts the key card into its dock, a radio signal is sent alerting the system that the room is occupied. When the guest leaves the room unoccupied, the removed key card automatically shuts off controlled lights and/or electronics and sets the in-room HVAC system back to its unoccupied/energy conservation mode. Hotels can cut energy consumption by 40 percent overnight by integrating wireless building automation controls.

Greater flexibility, lower costs

Together, the EnOcean and TCP/IP communication protocols provide buildings with unparalleled performance and flexibility. Wireless system providers such as Magnum Energy Solutions help bridge the communication protocols for the benefit of integrators and building owners.

EnOcean-enabled devices do not require line power or batteries and are therefore highly flexible in their positioning. Each wireless device has a unique ID address, so it can be integrated seamlessly in an IP network through an access point or gateway. This eliminates any elaborate or extra Web server systems for each sensor and actuator. A legacy network can be easily merged with energy harvesting technology to benefit from all its native advantages. The user is rewarded with more flexibility, comfort, and convenience, accompanied by low installation costs and reduced power needs.

More than 800 EnOcean-enabled energy harvesting products are now available worldwide. Building automation sensors and controls enabled by EnOcean include wireless switches, sensors, actuators, controllers, gateways, and building management systems. These products are available in both 315 MHz (for North America) and 868 MHz (for Europe).

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ECD in 2D: EnOcean’s intelligent energy harvesting sensors and switches transmit sensor data within a building to control lighting and HVAC systems without the need for cabling. Use your smartphone, scan this code, watch a video: http://opsy.st/ycZU6e.

Jim O’Callaghan is president of EnOcean Inc.

Mike Giorgi is president of Magnum Energy Solutions.

EnOcean Alliance 801-943-3215 jim.ocallaghan@enocean.com www.fb.com/pages/EnOcean-Alliance/109269292485427 www.linkedin.com/groups?mostPopular=&gid=3578554 @EnOceanAlliance www.enocean-alliance.com

Magnum Energy Solutions 866-271-3961 mike.giorgi@MagnumES.com www.linkedin.com/company/magnum-energy-solutions-llc www.magnumenergysolutions.com

Jim O'Callaghan (EnOcean Inc.) and Mike Giorgi (Magnum Energy Solutions)
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