Chandler City Hall

Founded in 1891, Chandler, Arizona, today is a city of 240,100 in Maricopa County, a major suburb of Phoenix.

Marian Norris is Chandler’s assistant city manager. “Seeing the inevitable need for office consolidation, for more than 20 years we have been setting aside funds to pay for a new municipal complex,” she said. “We wanted a mixed-use facility to cater to the community’s needs and serve as an icon of excellent design and sustainability.”

Tapped to design and engineer a five-story tower that would be central to new municipal campus was the Phoenix office of SmithGroupJJR (Smith). The resulting 137,000-square-foot civic center campus includes city offices, council chambers, a television studio, a printing center, a community art gallery, a courtyard and a parking facility. In May 2013, Chandler became one of only 24 city halls in the U.S. to receive LEED® Gold certification from the U.S. Green Building Council (USGBC).

Challenge: Selecting a failsafe HVAC system to protect 26 electrical rooms and data closets.

Jon Silhol, PE, LEED AP, BD+C was Smith’s lead mechanical engineer on the project. For the city hall’s vital nerve centers — 17 electrical rooms and nine data closets located throughout the campus — he needed a high-performance HVAC system that could handle the constant heat gain produced by the electrical equipment that would also meet the city’s energy reduction goals. It was imperative for Silhol to specify a failsafe, mission-critical system to keep the temperature in these rooms at a constant 75 degrees Fahrenheit: These systems simply could not fail.

For utmost security, the HVAC system for these nerve centers had to be separate from the unitary control systems of the other buildings. Silhol quickly selected a Variable Refrigerant Flow (VRF) zoning system from Mitsubishi Electric US, Inc. Cooling & Heating Division (Mitsubishi Electric), Suwanee, Georgia.

Solution: A Mitsubishi Electric Y-Series system is selected as the “industry’s most reliable” for mission-critical cooling.

“I had seen this VRF technology work successfully in other projects locally. The Y-Series technology is the industry’s most reliable system for mission-critical data centers,” Silhol said. “And the diversity of Mitsubishi Electric systems provided me with other excellent options for the public spaces in Chandler’s buildings including the TV studio, print shop, some small offices, elevator stairwells, bathrooms and hallways.” For these spaces, Silhol selected the R2-Series — the industry’s only two-pipe heat recovery system that simultaneously cools and heats multiple zones.

For critical emergencies, Silhol said the Mitsubishi Electric system provides another big advantage. With the VRF zoning system separate from the HVAC systems powering the rest of the campus, in the event of a catastrophic power failure, the stand-by generators can power just the Y-Series and one of the R2-Series systems. This enables continued cooling of the nerve centers without having to power HVAC for the rest of the complex. The electrical load requirement of the Y-Series is low compared to other HVAC systems, making it even easier for a generator to power.

Overseeing all systems is the responsibility of Kris Kircher, facilities maintenance manager for the City of Chandler. “Selection of the Mitsubishi Electric system was the right choice for our nerve centers,” Kircher said. “In addition to the energy savings we have witnessed, I have been delighted with the trouble-free performance of the Mitsubishi Electric systems. I especially like the design and diversity of the equipment which gives me the flexibility to place the proper fan coil into the right space with either ducted or wall-mounted units.”