AURORA, Ohio - The installation of a BACnet-enabled variable-frequency drive (VFD), working in tandem with the Automated Logic Corp. building automation system (BAS) at the Aurora City School District, could be a sign of things to come.

The drive offers BACnet without hardware additions. It started operating a motor on an air-handling unit (AHU) at the district's Harmon Middle School in July 2004. System integrator Comfort Control Group Inc. (CCG), Richfield, Ohio, is the district's energy management partner.

CCG installed the drive, manufactured by ABB Inc. (New Berlin, Wis.), and set up the direct interface to the BAS. CCG is a relative newcomer to the world of energy services, building automation, and temperature control. The company began eight years ago and has 10 employees serving schools, hospitals, and government buildings in Northeast Ohio (

"Such an installation, up and running, confirms that true open protocol has arrived for drive and motor control users in the HVAC industry," said Jeff Miller, HVAC sales manager for ABB Inc., Automation Technologies, Low-Voltage (LV) Drives.

"From a vendor-manufacturer perspective, it's extremely satisfying to see this development work in serial communications proved out in real-world, real-time conditions."

A screen shot shows how the BACnet-enabled VFD can be monitored from a remote location.

Glimpse Of The Future

BACnet is available as a Flash-loaded option in ABB's ACH550 low-voltage AC drive series. BACnet is an open communications protocol developed by members of the engineering community.

For Aurora building operations personnel, the BAS/VFD technology makes remote access, diagnostics, and control easier. "If you can get to a PC and an Internet browser, you can monitor and modify your HVAC operating conditions from wherever you are," said Mike Olson, manager - HVAC applications, ABB Inc., Automation Technologies, LV Drives.

The BACnet open protocol relieves operators of "the need for the expense and challenges of wiring gateways from their VFD components to the BAS," so the connection and information is getting more and more direct, the manufacturer said.

According to Olson, "Real-time serial communications means better information, which enables operators to make better energy-management decisions."

BACnet was designed to provide all the services needed by a full-fledged building automation system. Having the VFD controllers speak "native BACnet" means they can easily and seamlessly be integrated into the system, according to ABB.

In the past, VFD controllers could only be connected to the BAS through a gateway; a translator module had to be programmed on a point-by-point basis. Or, they could be hard-wired into the system, providing a minimum of control and monitoring points. ABB said its native BACnet controllers can be directly connected to the BACnet system and take advantage of features like auto-discovery, dynamic binding, time synchronization, and read/write variable requests.

Open Cooperation

The spirit of cooperation between partners can run through several levels. On this project, CCG's working relationship with Aurora Schools enabled CCG to win the bid.

"We have a maintenance contract and a past relationship with the Harmon Middle School," said CCG owner Brian Wagner. "We have provided service work for the entire district. The district decided to upgrade the controls in Harmon Middle School to Automated Logic.

"We chose Harmon as a test site for the BACnet interface," he continued. "The project was headed up by project engineer Brian Tenney and control technician Ed Rebish."

Wagner said positive feedback from the district after the work was completed included comfort improvements and energy savings. But relationships don't end there.

Representatives from ABB ( continue to meet with fellow members of the BACnet Manufacturers Association (BMA, to discuss strategic initiatives for the BACnet community.

BMA members include Alerton Technologies Inc., Andover Controls, Automated Logic, Honeywell, Johnson Controls, Siemens Building Technologies, and Tridium. These and other members joined forces to identify methodologies for reinforcing BACnet as an end-to-end communications protocol.

BMA encourages the successful use of BACnet in building automation and control systems through interoperability testing, educational programs, and promotional activities.

Members include companies involved in the design, manufacture, installation, commissioning, and maintenance of control equipment that uses BACnet for communication.

Publication date: 04/11/2005