Arden Building Companies knew that a pressure independent (PI) HVAC system would help a new Massachusetts high school meet its long-term sustainability goals, but there were concerns about the cost. Belimo Aircontrols’ PI control valve offered the perfect balance of performance and affordability, and Belimo went a step further, providing piping packages that cut up to 80 percent of labor costs.
Building a Green School
Massachusetts is considered a leader in the United States when it comes to energy efficiency standards, and the state provides financial incentives to districts that build highly efficient schools. New construction is expected to conform to the ninth edition of the Massachusetts State Building Code 780 guidelines, which closely follows the energy efficiency requirements of ASHRAE 90.1-2013.
Under the Green Schools Program, the Massachusetts School Building Authority rewards school districts an additional 2-percent reimbursement for projects that meet its sustainable building design requirements. All new schools in Massachusetts are required to exceed ASHRAE 90.1 by at least 10 percent. Green Schools, however, must achieve LEED certification, which requires that buildings exceed the energy efficiency requirements of the ASHRAE Standard 90.1 by at least 20 percent.
Attleboro High School (AHS) broke ground in October 2019 on an all-new $260 million campus, representing the largest municipal undertaking in the history of Attleboro. The new AHS is a four-story edifice encompassing 475,000 square feet with the capacity to accommodate 1,725 students. It opened in September 2022.
“The Green Schools Program is a system of reimbursement that provides monetary benefits to schools that opt for sustainable, high-performance designs,” said Derek Bride, principal at Consulting Engineering Services (CES). “The Green Schools Program was certainly on our minds from the start of the project, and we wanted to ensure they’d be eligible for benefits,” Bride noted. In the case of AHS, meeting the goals was anticipated to result in reimbursement of at least $4 million.
Under Budget Pressure
With overall budget considerations in mind, CES originally designed a traditional pressure dependent HVAC system. “Engineers often assume that going PI is going to be too costly in terms of parts, but it’s not always the case,” said Paul Carter of Arden Engineering Constructors and Earthwise Energy Technologies, two of the Arden Building Companies that served jointly as the mechanical and controls contractor on the job.
Pressure independent HVAC systems offer substantial benefits over traditional pressure dependent designs, providing improved energy efficiency and lower maintenance costs over time. In addition, PI systems can save money during the construction phase.
“In a PI system, the need for circuit setters and manual balancing is eliminated because each control valve regulates its own flow rate regardless of pressure changes. This reduces both materials and installation costs,” Carter explained.
Familiar with Belimo’s PI control valve offering, Carter quickly concluded that the Belimo electronic PI valve (ePIV) was an ideal choice for the larger valves in the system. “The ePIV is great for managing higher flow rates,” Carter explained. “The integrated electronic flow sensor uses a robust control algorithm which talks to the actuator and adjusts the valve to compensate for pressure variations, performing dynamic balancing. This ensures system efficiency.”
The ePIV assembly integrates a characterized ball valve, a high-performance actuator, a flow sensor equipped with glycol compensation, a temperature sensor, and flow control logic all in one unit. Despite fluctuations in system pressure, the ePIV maintains the flow setpoint by adjusting the characterized control valve based on the measured true flow.
“We used the ePIV in parts of the system where the flows were above nine gallons per minute (gpm), about 62 assemblies in total. But, for flow rates under nine gpm, we went with an affordable, compact mechanical PI solution from Belimo, the two-way ZoneTight PIQCV,” Carter said.
The Belimo ZoneTight PIQCV is a mechanical PI control valve with an ultra-small form factor, making it ideal for tight spaces. It combines a spring-action differential pressure regulator with a two-way valve to ensure a consistent flow regardless of any variations in system pressure. The PIQCV’s actuator operates at just 0.3 W, which conserves energy and transformer power. Belimo 223 PIQCVs were used throughout the AHS system.
Learn more from this 30-minute recorded webinar, Next Generation of Pressure Independent Valves: Enhance HVAC System Performance and Energy Efficiency: https://e.video-cdn.net/watch?video-id=-ihJsxRRh-rQHX3PpYUR5M&player-id=8MBkSDsjvQFuaZtsY-KWU9&channel-id=84981
Added Savings
While pivoting to a PI design saved the costs of circuit setters and manual balancing, additional savings were needed to keep the project under budget. Carter reached out to P.J. Qvarnstrom, RetroFIT+ business manager at Belimo, to see whether other savings could be achieved. “Piping packages are a great way to save the customer some money on labor,” said Qvarnstrom.
Aaron Nobel, piping packages product specialist for Belimo, said, “P.J. approached me about the Attleboro High School project, which called for hundreds of ePIV and PIQCV assemblies that needed a complete solution—including unions, isolation valves, and isolation strainers. We were able to provide piping packages for these valves which cut down on labor by up to 80 percent. Plus, the packages take up half the space compared to standard individual components.”
Belimo delivered nearly 400 preassembled piping packages, creating the additional savings needed to provide AHS a more efficient, lower maintenance, PI HVAC system for about the same cost as the originally designed pressure dependent system.
“Thanks to Belimo, we were able to deliver the customer a far superior system for the same amount of money,” Carter added. “Using PI valves cut costs on parts and manual balancing, plus the piping packages really saved on labor,” he said.
“The current projected energy usage in the building is 32 kBTU per square foot, which is 36 percent better than the baseline,” according to Dave Hillburn, senior mechanical engineer at CES. “That well exceeds the performance required to become LEED certified and receive the 2-percent reimbursement. The system will run more efficiently, will be easier to maintain, and will save the school money down the line.”
For more information, visit www.belimo.com.
Perfect for PI
Belimo electronic PI valve (ePIV) combines performance and affordability for PI HVAC systems:
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- Ultrasonic flow measurement technology and glycol compensation enable true flow measurement and total volume readings.
- A temperature sensor integrated into the flow body allows accurate fluid temperature measurement and glycol monitoring.
- The ePIV maintains PI operation, eliminating the need for manual balancing valves, which reduces installation and commissioning time.
- Digital workflows support device commissioning and operation with the Belimo Assistant app.
- The Belimo Assistant app enables remote calibration and commissioning report that can be generated automatically.
