This 35-yr-old school’s controls were comprised of a mixture of pneumatic and standalone DDC. With no centralized control and monitoring, the aged HVAC system ran inefficiently, resulting in numerous comfort complaints. An award-winning retrofit and implementation of new controls systems changed all that.

Connolly Middle School (Tempe, AZ) won an Arizona Governor’s Award for Energy Efficiency for 2005. This annual award is given to the government facilities that exhibit the greatest energy improvement through implementation of innovative energy applications, which not only reduce energy expenses but also improve the quality and comfort within the conditioned environment. The award received by Connolly Middle School was based upon work completed by Source Refrigeration & HVAC, Inc. using the Distech Controls easyCONTROLS™ solution.

Add-ons not meeting expectations

Connolly Middle School, built in 1972, is typical of many schools of this era that are struggling with the management of aged mechanical systems pieced together with an array of add-ons and repairs. The school was not providing the comfort and air quality desired for a learning environment, nor was it meeting the energy efficiency expectations for a modern facility.

The school’s campus consists of 184,034 sq ft of conditioned spaces arranged in six separate buildings. Each building has separate mechanical systems including centrifugal and reciprocating chillers along with multi-zone, VAV, and constant volume AHUs, all served with electric heat. Control systems were comprised of a mixture of pneumatic and standalone DDC. With no centralized control and monitoring, the aged HVAC system ran inefficiently, resulting in numerous comfort complaints.

 In an effort to streamline the process and to ensure that the school received a solution that met their needs and budget, the school’s management elected to pursue a D-B process with a selected group of HVAC contracting firms. This acquisition process provided for a quick and thorough assessment of the facility’s needs with detailed proposals, and allowed them to make the best choice of contractor and BAS solutions.

All about control

The school management selected the proposal of Source Refrigeration & HVAC, a Distech Controls Open System Dealer. The solution focused on the airside system and controls as the areas that would provide the greatest improvement in environmental air quality and comfort, and reduction in energy consumption.

The evaluation of the central chillers, cooling towers, and pumping systems concluded that these systems, other than lacking good control, were basically solid, efficient systems. Source Refrigeration & HVAC thus designed a system retrofit that entailed the replacement and modernization of all of the airside equipment, including:

  • Installation of 60 VAV boxes
  • Installation of an energy recovery wheel to precondition the outside air
  • Repairs and cleaning of AHUs and ductwork
  • Valve replacement and repair
  • Installation of VFDs on all major AHUs

The BAS installation using Distech Controls’ easyCONTROLS LonWorks® solution comprised a total of 650 points and 112 controllers. The control system included:

  • Central plant control using ECU-88, EC-12 (LonMark® certified programmable controllers)
  • AHU control using EC-12 and EC-8 and EC-67 (LonMark certified programmable controllers)
  • Eight-five VAV controls using EC-VAV-L (LonMark certified configurable controllers
  • RTU control using EC-RTU-L (LonMark certified configurable controllers)
  • BTU meters
  • LonWatcher LonWorks network management tool
  • Programming using LNS®-based plug-in for configuration and custom programming
  • User interface: Web browser access as well as scheduling, trending, alarm management, and normal user adjustments using an Echelon® i.LON® 100

   “We encountered just about everything you could expect in a 30-plus-year-old school, so we had our work cut out for us,” said Mike Ellis, of Source Refrigeration & HVAC. “When we finished, we made sure that the quality of the environment was what each of us would demand for our children.

“A key component of that was the control system. It was critical that the school’s maintenance staff be able to monitor and control the systems to ensure that good air quality was always being delivered and energy efficiency was being maintained.”

A 34% reduction of previous costs

Connolly Middle Schools now has the exceptional environment air quality the students need for learning and a substantial reduction in energy and maintenance cost. The energy savings for the first six months was over $58,000, a 34% reduction of previous costs.

John Dermer, facility maintenance supervisor for the Tempe Elementary School District #3, added: “We are pleased that we now can control and monitor the CO2in the air at the school. The recognition of the Governor’s Award demonstrates that you can improve air quality and comfort and at the same time achieve substantial energy savings.”