Airco Commercial Services, Inc. Partner in Sacramento’s first Ygrene Energy, PACE-Funded Building

Sacramento, California

Known for working with developers and building owners to identify system inefficiencies that improve their bottom line, Airco Commercial Services was a natural fit to partner with the team that retrofitted Sacramento’s first Ygrene Energy, PACE funded project at 520 Capitol Mall. PACE, or property assessed clean energy funding is an innovative way for local property owners to finance energy efficient, renewable energy and water conservation upgrades with no up-front costs. With a PACE-funded project, building owners can start saving on energy costs for clean energy upgrades through a special property tax assessment. In Sacramento, Ygrene Energy Fund and the city of Sacramento formed a pioneering public/private partnership in Clean Energy Sacramento, allowing both commercial and residential property owners to take advantage of PACE resources for energy improvements.

The 520 Capitol Mall building was the first project in Sacramento to successfully secure PACE financing to fund environmental improvements. Airco Commercial Services, a certified Ygrene contractor, worked with the building’s asset manager John Brennan, and engineer David Weston of Weston Associates to install a more environmentally efficient chiller for the 80,532-square foot project. The successful, $513,000 Airco Commercial HVAC installation is projected to reduce costs on the 520 Capitol Mall building by $47,000 a year for 25 years, while improving the property value in excess of the project cost. “The Multistack chiller with oil-free compressors has already reduced energy consumption by 25 percent in the first month alone”, confirmed David Dorsett, project representative for Airco Commercial.

Established in 1987, Airco Commercial is a full service HVAC contractor that helps customers create “smart buildings” by reducing energy consumption and operational costs through intelligent heating, venting, and air conditioning solutions.

With the success of the 520 Capitol Mall project, Airco Commercial is looking forward to similar project opportunities in the future. “With a focus on helping commercial building owners lower their energy costs by solving energy problems, we are an ideal partner for these types of projects,” explained Charles Jones, president of Airco Commercial Services. “We appreciate the chance to partner with business owners and organizations in creating long-term energy solutions.”

The design process includes extensive measurement of an existing building’s performance, providing an accurate picture of how a building is actually operating and what changes are needed to optimize operation for best efficiency and comfort. Very importantly, the Performance Design Approach creates an extended post-project commissioning period to sustain system performance and energy savings and includes user training to maximize sustainable energy efficiency and savings. Araki has always maintained that providing an efficient design is only as good as sustaining that efficiency from year to year.

Les Taniyama, PSIG-Hawaii, said, “We installed various types of meters on the existing chillers and HVAC equipment throughout the building. This allowed us to carefully define the building’s actual needs and cooling load. We measured not only the kW and kWh of the chillers and overall chiller plant, but all other HVAC components. We learned that the cooling capacity of the existing chiller plant (320 tons) was more than twice the actual cooling load (150 tons) because the Moore Hall chiller plant also serves a chilled water loop that includes other campus buildings. As a result, Moore Hall was often significantly over-cooled, resulting in comfort complaints from students and faculty.”

In addition to setting up extensive instrumentation to study the building, the RMA design team did a walk-through of the building. Tatiyama said, “We counted 68 sweaters on the backs of classroom and office chairs—plus a couple of floor heaters tucked under desks in the offices! This building had some serious comfort issues!

Fifty percent of the energy use in buildings such as Moore Hall is for HVAC. And half of that energy use is for the chillers. Twenty-five percent of total building energy use is a big number. Araki knew that by establishing the best operating environment for the chillers and condensers, he could achieve the best energy efficiency.

“With a focus on helping commercial building owners lower their energy costs by solving energy problems, we are an ideal partner for these types of projects….”

Charles Jones President of Airco Commercial Services


A Tough Environment
Another challenge facing the Moore Hall project team was that the wet bulb temperature in Hawaii is always very high. RMA’s performance designs attempt to provide for a very stable operating equipment condition under variable ambient weather conditions. The team discovered that centrifugal chillers don’t like rapid changes in operating conditions such as water flow rates or condensing temperatures. In fact, some chillers are just ‘too smart’—their controls are so advanced that they ‘remember’ previous operating conditions and are always adjusting the equipment controls to allow for changes, like rapidly changing condenser water temperatures due to passing rain showers on a sunny day.

Eric Nakagawa, RMA, said, “ASHRAE standards call for being able to operate at 50 percent load capacity at 65-degree condensing water temperature. You literally cannot get to those conditions in Hawaii. However, Multistack provided the systems engineering and product applications support to give us the confidence that the Multistack chillers would perform well in Hawaii. These Multistack chillers can successfully operate at as little as 20-percent load with 70–75-degree condenser water temperature!”

The system was designed to accommodate operation of one or both chillers while operating both cooling towers in either mode. The condenser water pump VFD’s automatically change condenser water flow rate per chiller for single or dual chiller operation. This provides proper flow rate through the cooling towers and chiller in all operating modes. Herman Siu at Trane Hawaii provided selections of Evapco cooling towers, paying attention to details like cooling tower cell minimum flow rates and condenser water flow rates to optimize performance.

During the post-project commissioning process the project team also adjusted air handler VFDs to minimize or eliminate rapid changes in airside operating conditions, thereby stabilizing chilled water flow and chiller performance. The design allows Moore Hall operators to operate the new Multistack chillers in either series or parallel configuration to achieve best efficiency for conditions—series configuration is usually most efficient. The plant is also configurable to allow for building-only cooling or to include the loop (either in series or in parallel connection).


Moore Hall Design Criteria Included


  • Improving operation, performance, efficiency, reliability, flexibility, serviceability of the mechanical equipment or system being replaced or repaired
  • Sustainable, environmentally-friendly design consideration (e.g. refrigerant selection, energy efficient lighting where replaced, ice thermal storage, heat recovery, etc.)
  • Maximize existing mechanical system enhancements to allow future expansion and new technologies. (E.g. maintaining the existing chilled water loops, VFD’s for variable volume systems, installing premium efficient motors, etc.).
  • Address and/or improve indoors environmental conditions (temperature/humidity)
  • New Energy Management and Control System (EMCS), to control central plant, roof equipment, air handlers (with VFD’s) and VAV terminal units.
  • EMCS allows for the scheduling of all mechanical equipment.

New Multistack Chillers Installed
Blake Araki developed a budget that included new chillers, adjusting the airside systems and integrating air handlers and VFDs into an optimized, efficient system. The entire energy management system plus all the thermostats and VAV terminals throughout Moore Hall were replaced.

Araki agreed with RMA to install two 160-ton Multistack chillers with the MagLev® compressors and flooded evaporator because the project required optimum capacity to be able to serve the building and the four-building loop. Eric Nakagawa, senior designer at Randolph H. Murayama & Associates mechanical engineers, said, “The Multistack chillers have just the right size and cooling capacity. These chillers fit university-type buildings very well and their performance makes them an excellent choice.” RMA’s Lance Suzuki, P.E. assisted in designing the HVAC system upgrades.

The MagLev compressors provide efficiency, reliability and redundancy advantages. The magnetic bearings nearly eliminate rotational friction, require no oil and since the chiller has multiple compressors, the building automation system can very closely match chiller output to actual load conditions. If one compressor were to fail, the other compressor provides redundancy.

Another factor in favor of the Multistack chillers is the compact design. Although other makes of chillers would have fit into Moore Hall’s basement equipment room, those chillers were too long relative to future serviceability such as heat exchanger tube cleaning or replacement. Multistack was flexible and worked with PSIG and the University to provide heat exchanger shells of the necessary length.

Another advantage of the Multistack chillers is the FlexSys® controls that provide unmatched controllability to adapt and fine-tune overall chiller and individual module/compressor operation for redundancy and to achieve optimized performance

throughout the broad spectrum of operating environments at Moore Hall. In addition to on-site control, the Moore Hall

FlexSys controller can be accessed in real time, anytime and from anywhere in the world via laptop, iPad, or Smart Phone.

FlexSys control flexibility allows end users to field connect devices that allow it to either respond to BAS commands, send the BAS information, or control auxiliary devices such as isolation valves, pumps, cooling tower fans, temperature reset, load limit, etc.

In addition to water-cooled flooded chillers like those installed at Moore Hall, FlexSys controllers can also be applied to water-cooled DX chillers, air-cooled flooded chillers, air-cooled DX chillers, built-up DX systems, modular chillers, dedicated heat recovery chillers and a host of innovative applications never before possible.

New EMS System
The University of Hawaii is not only saving significant energy costs at Moore Hall, but comfort is greatly improved while maintenance time and costs are sharply reduced. The improved energy management and control system makes the HVAC system virtually self-correcting—or it notifies operators of an issue requiring corrective action. The new EMS allows operators to better see and understand the entire building.

Kenneth Richardson, President of Island Controls, collaborated with RMA and PSIG-Hawaii to create custom programming for the Automated Logic Corp. “Web Ctrl” EMS and control system. Integrating graphics with custom programming lets operators visualize building performance at a glance. Richardson said, “These custom dashboards provide real-time status by switching from screen to screen. The custom control and reporting schemes required for this performance project were accommodated by Automated Logic’s open object oriented protocol.”

Moore Hall went from an average chiller efficiency of 0.68 kW per ton, to 0.38 kW per ton. Taniyama notes that three years ago the University installed VFDs on all of the air handling units and the design team initially didn’t think that they would be able to save much energy at Moore Hall. However, in January, 2010, the first full month of operation with the new chillers, cooling tower and systems adjustments, chiller plant energy use at Moore Hall decreased by 74 percent compared to February, 2009. The new system is saving significantly more energy than originally projected.

Average office/classroom Energy Use Index (EUI) was 22.8 kWh/square foot/year. In 2009, following installation of VFDs on the Moore Hall air handlers, the Moore Hall Energy Use Index was 19.8 kWh/square foot/year or 13 percent less than the average building EUI. In 2010, after installation of the new Multistack chillers, cooling tower and energy management system, the Moore Hall EUI was 11.6 kWh/square foot/year—49 percent less than 2009!

Although projected annual energy savings were calculated at 275,000 kWh, in 2010 the measured annual energy savings totaled 621,000 kWh. At $0.25/kWh, that’s $155,250 savings per year—and more as energy costs increase.

Blake Araki said, “The energy savings numbers speak for themselves plus the system is more stable and operates much more reliably and efficiently. Comfort levels are definitely better. The Multistack chillers have met all of our performance requirements at Moore Hall.”

“Multistack has really gone to bat for us on this project,” said Eric Nakagawa. “Their support is excellent. As a designer I measure the quality of a manufacturer and their products by how well they handle problems. There were times when we called Multistack when it was eight o’clock in the evening at their headquarters in Wisconsin. The Multistack team has never walked away from any problems.”

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