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In-Building Use and Built-up Systems

The in-building test involved deployment of a system based on wireless technology from Inovonics Wireless, Inc. in a federal facility. Inovonics has cost shared in the project by providing equipment, technical consulting, development of a new hardware component, and on-site installation assistance for the project. Operations personnel at PNNL enthusiastically participated in the project and used the data collected for building operation. The PNNL Facilities and Operations Office supports this project with their own funds (beyond DOE BT funding) by providing staff time for participation in project planning, system design, wireless system installation, system use, and data collection. This site and technology also show promise for extension to wireless control of air handlers in the building, which could serve as an excellent extension of wireless technology beyond sensing into building controls. The value of both wireless sensing and wireless control is in reducing the incremental cost of better sensing/control by eliminating (or reducing) the number and length of wires, which ordinarily cost from 20 to 80 percent of an installed control or sensor point. Better control shows great promise for implementing and ensuring high-quality, energy-efficient building operation.

The in-building demonstration site was a heavy steel-concrete office building with a total floor area of about 70,000 ft2 distributed over three floors. It is located on the campus of Pacific Northwest National Laboratory (PNNL). The HVAC system consists of central cooling, boiler, and ventilation system with 100 variable-air-volume (VAV) boxes. The central energy management and control system (EMCS) controls the central plant and the lighting system. A wireless temperature-sensor network with 33 battery-powered temperature transmitters was installed to measure zone-air temperatures. The zone-air temperatures were then used as input for a chilled-water reset algorithm designed to improve the energy efficiency of the centrifugal chiller under part-load conditions and reduce the building’s peak demand without significantly increasing the energy use by distribution fans.

Layout of Inovonics Wireless Sensor Network (PDF 6KB)

Energy Savings

Energy savings were largely caused by the shutdown of the supply and return fans and, to a lesser degree, to the reduced thermal loss during the night resulting from implementation of a new night setback strategy. In this strategy, the supervisory control program was augmented to schedule night setback starting at 6 p.m. and to suspend it if an office zone temperature exceeded a threshold temperature of 78°F during the cooling season and 55ºF during the heating season. Trend-logs of runtime using the new night setback strategy were used to estimate the electric energy savings at approximately $5000 annually. We attribute the cost savings to the wireless sensors because without the data they provided, the building managers were unwilling to use ventilation night setback.

In-Building System Photos

To view the larger image click on the thumbnails.

Sensor & Transmitter	Translator	Receiving Unit
Repeater	All components
Translator and Receiver Units	Location of a wireless temperature sensor in an office space.