When it comes to writing an important research paper, it’s essential to include references. That’s exactly what Tom Mangogna had his district engineering staff do when it came time to research using Daikin for their school district.
He approached school districts throughout the U.S. that had Daikin systems installed for at least one year in schools of comparable size. After hours of rapid-fire Q&A over conference calls with these districts, Mangogna said he was convinced.
Mangogna runs facilities for the Hazelwood School District north of St Louis. The district includes 20 elementary schools, six middle schools, three large high schools, and some early child care centers — over 30 buildings in all. Since most of their HVAC systems were 15-25 years old, maintenance costs were rising. Mangogna knew there had to be more efficient systems on the market that could help reduce energy expenses.
While attending product seminars sponsored by Thermal Mechanics Inc., Tom and Steve Limas of KAI Design & Build in St. Louis learned about the concept of variable refrigerant volume (VRV) and, specifically, the Daikin product. KAI had done work for the school district in the past and had also worked with VRF/VRV systems on prior projects. So Steve Limas suggested it would be worthwhile for them to investigate the concept on some of the upcoming school projects.
“Daikin is at the forefront of efficiency and design flexibility,” he said. “VRV’s modulating compressor results in a more efficient refrigerant system, matching the load exactly and saving energy.”
For Tom Limas, it was all about proving performance. KAI had indicated they could take advantage of building diversity using the heat recovery capability to provide higher comfort levels with reduced tonnage, which would then translate to significant energy savings. However, he wanted his engineering staff to be completely confident in the concept. They reviewed the technical information and asked questions of the other districts around the country.
“Our guys came away from those conversations saying we need to bring in this new technology — there are so many advantages,” he said. “Maintenance will go down, the energy savings are there, and teachers will have more flexibility to set their own temperatures. How do we move forward?”
Once designs and specifications were complete, Tom Limas had one more set of conditions.
“We wanted contractors experienced with the technology,” he said. “Bidding contractors were required to show successful installation in multiple schools with equivalent square footage. Even though the VRF/VRV technology had been in use worldwide for 30 years, it was new to some contractors here. We didn’t want to be on their learning curve.”
Hazelwood School District now has seven schools with Daikin air-cooled heat recovery systems installed, and three more that were set to be retrofitted. From a design perspective, Steve and Tom Limas like the greater modulation capability of the Daikin VRV system, the flexibility of having more steps in tonnage, and a wide range of indoor units from which to select in applying the technology. In the case of Hazelwood’s Northwest Middle School, a more energy- and maintenance-intensive 200-ton two-pipe system was replaced with a Daikin air-cooled heat recovery system. The decision to use heat recovery allowed the designers to take advantage of shifting schedules to maximize energy savings.
“We have reduced installed tonnage in some cases by close to 50%, with over 300,000 sq ft installed. The reasons for going with these systems keep multiplying,” says Tom Limas. “Our guys have all been trained in commissioning and servicing these systems, but they don’t have to spend a lot of time on them. The Daikin units are low maintenance; they’re compact, and so quiet — the teachers love that — and they can adjust their temperatures within a certain range that keeps our energy savings intact.
“And they really love that we no longer are either in heating or cooling mode. One teacher on the south side of the building, who gets significant heat load from the sun, may want to cool their room while another teacher on the north side may want to heat their room. Daikin makes it possible to do both with the same system,” he said.