Wireless Sensor Network for Energy Efficient Real-Time Control of Indoor Climate

Software and Hardware Improves Building HVAC Energy Efficiency

This wireless sensor network monitors and enables indoor climate control in commercial buildings to save energy while maintaining comfort and air quality. Buildings are responsible for more than 40 percent of the total energy consumption in the United States, while heating, ventilation, and air conditioning (HVAC) systems account for 50 percent of that energy usage. Poor design and inefficient operation of an HVAC system leads to a significant amount of energy waste. Existing systems operate so that conditions are maintained in a predetermined range whether the building is occupied or not; more sophisticated systems use a time-based schedule, controlling variables based solely on time, not environmental factors that may impact indoor climate. Researchers at the University of Florida have developed a wireless sensor network that enables climate control within buildings based on real-time measurements of occupancy and other factors. The sensor nodes measure environmental variables and then wirelessly transmit data to a central computer that controls the HVAC system. The sensor system is a low-cost, energy-efficient retrofit measure, easy to use in an existing building or in new construction.

Application

Measures indoor climate and occupant presence in real-time to improve HVAC energy efficiency

Advantages

• Increases operation efficiency of building’s HVAC system, reducing energy consumption cost
• May be retrofitted in existing buildings, requiring no building modifications
• Measures various indoor climate conditions, enabling real-time thermal comfort of occupants and indoor air quality while saving energy
• Compatible with existing HVAC systems, eliminating need for costly replacement of existing hardware

Technology

This sensor network measures real-time occupancy and other environmental factors -- such as temperature, humidity, and CO2 levels -- to enable indoor climate control in buildings. The two main components include a number of sensor nodes and the supporting computing hardware and software for collecting and transmitting data to a remote database. Each sensor node contains a microprocessor, radio, and a number of sensors to measure environmental climate variables at the location of the node and transmit the data to the centralized computing hardware. The software collects and sends the data from all sensors within radio range to a remote database. This technology measures indoor climate conditions to generate and send multiple control inputs to an air handling unit (AHU) or variable-air-volume (VAV) box. The sensor network and the algorithms that use the sensor data and control the HVAC equipment have been tested in a LEED-silver certified building in the UF campus, resulting in a 30 percent reduction in energy use with no effect on the measured and perceived indoor climate.