Energy efficiency
Give HVAC the edge with batteryless/wireless controls
Intelligent HVAC control systems using batteryless wireless technology can leverage energy saving opportunities with low installation effort and fast ROI. Retrofit projects are no longer a hurdle for an improved carbon footprint argues John Corbett
40 per cent of the UK’s primary energy and cause the same percentage of carbon emissions. In commercial buildings such as hotels, hospitals, schools or offices, more than half of this energy consumption is used for heating, ventilating and air conditioning (HVAC). Here, energy reduction comes with a specific challenge: occupants do not pay for the energy bill directly and therefore rarely contribute to an improved carbon emission. Ultimately, buildings can pro- vide the highest savings potential and lowest ROI time frames. So, how can these potentials be tapped without the occupants’ support? It calls for innovative, sustainable technologies that can be easily installed at relatively low cost. Wireless automation systems are such technologies. They mon- itor, control and conserve energy, delivering savings between 20 per cent and 40 per cent.
A matter of power
The intelligent control of energy requires sensors to collect the rel- evant data from several points of measurement together with receivers to process the informa- tion. A larger system can comprise hundreds or thousands of these sensor devices all requiring power and communication capability. For cost-effective retrofit projects, cables are not an option as they would cause high installation mess, effort and cost. Wireless solutions are preferred as they can be flexibly placed and eliminate the need to install wiring and con- duits. However, the challenge of powering the devices remains: batteries can prove to be a draw- back in complex applications. Batteries last for only a limited time, depending upon the applica- tion, and must therefore be replaced regularly and disposed of properly. A large system, for example in an office, comprising 10,000 wireless units, each pow- ered by two batteries, could require the facility manager to change approximately 30 batteries
18 | September 2014 | HVR
each day. This is an unacceptable degree of effort and cost.
Batteryless approach This is where EnOcean energy harvesting wireless solutions come into play. Energy harvesting wire- less technology is derived from a simple observation: where sensor data resides, sufficient ambient energy exists to power sensors and radio communications. Harvestable energy sources include motion, indoor light and temperature differentials. These ever-present sources provide suffi- cient energy to transmit and receive radio signals between wireless switches, sensors, actua- tors and controllers, sustaining vital communications without cables and batteries. Instead of batteries, miniaturised energy con- verters generate power for the wirelessly communicating devices, keeping the maintenance effort to a minimum while still enabling highly flexible installations. The self-powered devices use the international wireless standard ISO/IEC 14543-3-10 – a protocol specifically designed to support very low power devices, an order of magnitude lower than alterna- tive standards. The products achieve this by delivering very short data packets and by utilising the 868 MHz frequency band giv- ing robust signal propagation and minimal interference. The range of EnOcean wireless sensors is approximately 300 metres in open spaces and up to 30 metres inside buildings. Repeaters can also be used to extend the signals.
Wireless HVAC control system Based on batteryless wireless tech- nology, an intelligent HVAC sys- tem can be realised by intercon- necting automated thermostats, window contacts, humidity sen- sors, occupancy sensors and CO2 sensors. These are just a few examples of the products in place, to regulate climate control auto- matically. In an intelligent automa- tion system, for example, a room controller receives information
Typical uses for batteryless/wireless controls. Also see facing page
related to temperature, humidity, window position or CO2 from the respective sensors and controls the opening and closing of valve actuators for radiators. The room controller wirelessly sends information to an energy controller that calculates the demand as a function of outdoor temperature and flow temperature to control energy use.
The more complex a heating installation, the more information it takes to control it. Single room controllers with energy harvesting wireless technology and the inte- gration of self-powered wireless sensors to capture values can sig- nificantly reduce and optimise the energy needs of a modern heating plant. Additionally, information can be transmitted wirelessly to a heating regulator or programmer, without batteries, wiring and no need for maintenance or servicing.
Individual requirements If needed, the wireless devices can be integrated with other commu- nication protocols such as Ethernet/IP, KNX, BACnet or LON via gateway controllers that translate the EnOcean energy harvesting wireless protocol.
This enables building operators to plan a widely distributed automation system that adds value by combining easy installation, reliability and low maintenance effort giving a better user accept- ance of the energy control meas- ures. Due to this integrated wire- less system approach, sensors can measure energy consumption, and a website can be created visualis- ing status and trends. The user instructs the system over a web portal, for instance, to adapt set point data to an optimal level. In addition, batteryless wireless sen- sors can measure data, which together with the occupancy lev- els of a building, can be used by the automation system to calculate the required energy in specific periods of time.
Integrated room automation An example of an intelligent automation system integrating self-powered wireless solutions is the BREEAM-certified (Building Research Establishment Environmental Assessment Methodology) new Palace of Justice in Amsterdam. Here, an energy-efficient, productive and comfortable working environment
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