4 HVAC controls case studies that prove your building can save energy
An HVAC control system may be called a building management system (BMS) or an energy management system (EMS). No matter the name, they help the building systems to run smoothly while saving energy. They also help keep building occupants are comfortable. Since HVAC systems account for a good deal of a commercial buildings’ energy consumption, control systems can help save big on energy.
The State of Vermont operates two large buildings in downtown Burlington, Vermont. The Zampieri State Office Building and The Costello Courthouse have a combined square footage of 374,000 feet. That’s a lot of space to heat and cool! In 2016, the state engineers saw an energy saving opportunity.
Problem: These two buildings have variable occupancy levels. There is continuous occupancy by State employees, and the buildings are also open to the public. It was hard to control temperatures and keep all the spaces comfortable without hiking up the energy bills.
Solution: Occupancy sensors. Sensors trigger the HVAC system to reduce ventilation levels of empty spaces. The team integrated the existing lighting sensors with the HVAC control system. Now, spaces are not heated or cooled when they are empty. In the courthouse, the run times of the 135 fan-powered variable air volume (VAV) boxes were reduced. New settings and occupancy sensors meant that the powerful supply fans could be slowed down to generate further energy savings.
Gifford Medical Center in Randolph, Vermont has dedicated staff time and resources to save energy in their facility. In 2018, they joined Efficiency Vermont’s Continuous Energy Improvement (CEI) program with the goal of decreasing energy intensity, optimizing mechanical system, and increasing their Energy Star score.
Problem: The hospital has high operational costs driven by the cooling and dehumidification loads. Large commercial buildings like hospitals use chillers to achieve proper temperature control.
Solution: Gifford had the controls system assessed. From there they joined Efficiency Vermont's existing building commissioning program. Existing building commissioning is a process that identifies and applies operational improvements to an existing system. The team found several opportunities to improve the control of the chilled water system. Gifford chose to complete the savings opportunities with the greatest return on investment. They implemented control sequences including:
- A chilled water supply temperature reset
- A chilled water loop differential pressure reset
- Improved staging for the 90-ton chiller
While the team was on site evaluating the chilled water system, they discovered an extra opportunity to save on heating fuel. As a result, Gifford added insulation to the steam pipes in the mechanical room. This saved 1,600 MMBtu of fossil fuel – or 11,700 gallons of fuel oil.
Construction was complete on the Manchester Community Library in 2014. Updates to HVAC and control technology mean that even these relatively new buildings can still benefit from upgrades. After participating in Efficiency Vermont’s new construction program, the library knew they could reach out to Efficiency Vermont for support.
Problem: The library staff didn’t know how well the building’s HVAC systems were working, or if they were wasting energy. They wanted more control over the stand-alone variable refrigerant flow heat pumps (VRFs).
Solution: This project followed a two-phase approach. First, they installed a new central controller. This means they can control the heat pumps. They also brought their boiler plant onto the control system. Now they can track the performance of their boiler plant and heat pumps all in one place. Both systems are easier to control, and the controller can be accessed remotely. In the second phase they tied their energy recovery units (ERU) into their new control system. Now all the library’s HVAC systems are viewable in one location.
During the COVID pandemic these upgrades helped library staff adjust to changes in their daily operations. They increased ventilation levels and made changes to their occupancy schedules.
The Community College of Vermont (CCV) completed its Winooski Academic Center in 2010. The center serves over 2,000 students in the greater Burlington area.
Problem: Following the best practices for HVAC maintenance, CCV wanted to make sure systems were running well. Eight years after completion, the Academic Center needed a check-up. It was time for a Controls Preventative Maintenance (PM) contract. A PM is a strategic way to identify energy and cost savings in the building’s HVAC system.
Solution: CCV got in touch with their controls contractor and Efficiency Vermont to develop and agree upon a scope. After each PM visit, the controls contractor reviewed a report of their findings with CCV and the Efficiency Vermont team. CCV’s contractor made these improvements based on the findings:
- Reset hot water based on demand
- Investigated and mitigated bathroom exhaust flow issues
- Remediated issues with the heating and cooling fighting each other
- Improved the cooling tower sequence of operation
- Enabled modulating of Variable Frequency Drive (VFD) of the cooling tower fan
- Programmed the best start/stop
CCV’s preventative maintenance contract got their HVAC system running at high efficiency. They knew which systems were working well and could fix problem areas. Through the preventative maintenance contract, CCV saved 4% on their electric bills.
