While Platte River, as an organization, was a pioneer of renewable energy and green practices, its office headquarters did not reflect the company’s commitment to environmental stewardship. Jeff Menard, Platte River’s facilities and security manager, was growing increasingly concerned with the 23,500-square-foot, late-1970s office building’s poor thermal envelope as the building’s systems were essentially at the end of their useful life as the existing boiler and chiller provided sub-par comfort control, air distribution, and efficiency.

“I had a system that was shutting down bit by bit. We had to chop into the system time after time for repairs, and I was on constant service calls because of the poor cooling and heating abilities of the system,” said Menard.

In stark contrast with the diverse conservation initiatives of the rest of the company, Platte River’s headquarters had no energy-saving methods in place. When the building rated just a seven on a scale of 100 on Energy Star scoring, Menard decided to evaluate the building for areas where energy efficiency could be improved. Menard enlisted the help of Haynes Mechanical Systems (Fort Collins, Colo.) to come up with a plan.

They agreed to tighten the building’s thermal envelope and explored options to replace the building’s inefficient boiler and chiller. Haynes Mechanical Systems collaborated with Abrahamson Engineering Inc. (LaPorte, Colo.) and decided to replace the existing HVAC system with a variable air volume (VAV) system with high-efficiency gas boilers.

Complete Zone Control

According to Menard, it quickly became evident during the design phase that the VAV system wasn’t going to work for Platte River’s needs. Menard knew each office would need individual control to satisfy the different load requirements of offices in areas of the building with different orientations and also to accommodate employees’ individual comfort preferences.

“The client kept asking for more and more zoning, but the best we could offer with a VAV system was one box for every two offices, and that was still going to result in disagreements over the temperature in the offices sharing the VAV box,” said Mark Shadowen, project specialist, Haynes Mechanical Systems.

“With all those VAV boxes, the cost had significantly exceeded budget. Additionally, we were finding more and more places where space constraints would make all of that ductwork difficult,” added Roger Abrahamson, founder and president, Abrahamson Engineering Inc.

Menard, Abrahamson, and Shadowen decided to start from scratch and seek a different system to satisfy Platte River’s need for complete zone control and energy efficiency. Shadowen suggested looking at a variable refrigerant flow (VRF) system as an option.

“I had the idea of a VRF system in the back of my mind from the very beginning, specifically a water-cooled system,” said Shadowen. “Because this type of system was relatively new in the U.S., it wasn’t until the other systems proved incompatible that we decided it was the best bet.”

Shadowen was familiar with VRF systems from HVAC manufacturer Mitsubishi Electric Cooling & Heating but wanted to conduct more research to determine the cost benefits of a VRF system before making a final decision. Haynes Mechanical Systems and Abrahamson Engineering worked together to produce a 20-year life-cycle cost analysis and energy-savings comparison between Platte Rivers’ existing system, the VAV system, and the VRF system. The VRF system was projected to save Platte River more than $16,000 per year in electricity bills when compared to the existing system, and $5,000 more than the projected savings with a VAV system. Additionally, the VRF life-cycle costs came in at about $300,000 less than replacing the existing system, and over $475,000 less than that projected for the
VAV system.

“Because of the climate in Fort Collins, we felt that a water-source system was the best option for Platte River, as opposed to an air-cooled system,” added Abrahamson. “The building already had a cooling tower, and it made a lot more sense to have water-source heat pumps in this climate instead of air-cooled — it is a lot more efficient to extract heat from 70˚F water than from -10˚F outside air.”

Introducing Water-Source Systems

According to Abrahamson, it took a lot of education and a little convincing to get everyone on board with this new water-source VRF system. “Because this type of system was relatively new to us, we all had to have a bit of education to learn about the technology,” said Shadowen.

Shadowen enlisted the help of Charles Landherr, area manager, Mitsubishi Electric Cooling & Heating, and learned that the HVAC manufacturer offered the type of water-cooled VRF system Shadowen had in mind.

“Charles was great at educating us on this newer technology. It was because of his willingness to work with us and take the time to make sure we understood the system, and because of the helpfulness of our local HVAC distributor, Charles D. Jones Co., Denver, that we opted for Mitsubishi Electric’s WR-Series water-source solution,” said Shadowen.

To learn more about how the system would function, Landherr orchestrated a state visit in Wyoming where Menard was able to tour a building where a Mitsubishi Electric WR-Series system was installed. At Landherr’s advice, members from Haynes Mechanical Systems took advantage of Mitsubishi Electric’s extensive training program and attended classes on the technology in California, at one of the company’s six nationwide training centers.

“Through that education process, we learned that the Mitsubishi Electric system lent itself so well to all of our needs. Because of the extremely flexible zoning options, all of the individual offices could function on their own giving each employee full control over his or her space, and the VRF technology satisfied our emphasis on energy efficiency,” said Menard.

VRF Offers Easy Installation

The team began retrofitting the building in early May 2010 with the building partially occupied during installation. Starting with the second floor of the 23,500-square-foot building and working down to the first floor and mechanical room, the entire installation took less than three months as the project was completed by mid-August.

“The installation process only supported our decision to switch from a VAV to a VRF system. We kept running into more and more areas where we realized that it would have been extremely difficult to get ductwork into places that originally we thought we were going to be able to. Had we tried to install a conventional VAV system, we never would have made the tight deadline,” said Shadowen.

As Comfort Increases, Energy Costs Decrease

The Mitsubishi Electric WR-Series system, combined with high-efficiency foam insulation and the conversion of an existing rooftop air-handling unit into a dedicated outdoor air system with heat recovery and demand-controlled ventilation, helped the building achieve a high level of energy efficiency and personal comfort. The building is now aiming for an Energy Star rating of 50, and has its sights set on achieving a score of 75.

With the building’s increasing energy efficiency, its energy bills have gone down exponentially. From the system’s installation in August 2010 to February 2011, the system has saved over $23,000 to date when compared to the corresponding months of the previous year. During the winter months of 2010-2011, the system cost Platte River an average of 58 percent less in electricity bills than in winter 2009-2010.

The first real test of the system occurred in its first winter when sub-zero conditions hit Fort Collins in January 2011. According to Menard, in winters past when that kind of low temperature occurred, every office would have a 1,500-W space heater running and energy use would run at around 130 kW per day. This last winter, the energy usage ran at around 60 kW within the same timeframe without a space heater in sight and no comfort complaints.

“This system made my job easier beyond belief,” said Menard. “Day to day, we were putting out emergency fires because we had a system that was failing bit by bit. Now, it just runs.”

Publication date: 6/25/2012