The concept of energy harvesting
At the core of self-powered wireless sensors and switches are energy-harvesting technologies. The principles of harvesting energy, whether solar, wind, or water, have been used for decades, but self-powered, batteryless technology was developed only 10 years ago. For instance, EnOcean developed an energy-harvesting model from the concept that sufficient ambient energy exists to power sensors and radio communications.
When it comes to networking a wide range of sensors, switches, and devices, calculating the required cabling and then installing it is often an organizational challenge that requires a great deal of effort and money to get right. However, it is a challenge that energy-harvesting wireless technology has resolved. These wireless modules take the power they need to work from the environment around them -- from motion, light, or changes in temperature. Instead of batteries, energy-harvesting-centric controls use miniaturized energy converters to supply power to building energy management devices. Even the action of pushing a light switch gives sufficient energy to generate a wireless signal and switch the light on. The technology provides enough energy to transmit and receive radio signals between controls and sustain vital communications within an energy management system.
At the center of energy harvesting and wireless is the EnOcean wireless standard. The messages sent by this wireless system are brief and repeated several times within a 40-millisecond timeframe. By transmitting these data packets at random intervals, it is possible to ensure that the probability of collision is extremely small. As a result, it is effortless to operate a range of switches and sensors in close proximity to one another. Each module has a 32-bit identification number to exclude any possibility of overlap with other wireless devices. The products are available in both 315MHz (for North America) and 868MHz (for Europe).
Implementing a wireless energy-harvesting system
The BAS reduces 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. Widespread integration of building automation systems has been hindered by several factors. For instance, buildings have been expensive to retrofit (installation costs, slow payback, complicated installations), and interoperability between devices has been limited.
These classic barriers have been overcome by an ecosystem of energy-harvesting wireless controls that power themselves using energy infinitely available in building spaces.