Old Building, New HQ: VRF In Wisconsin
An energy services company has a habit of basing its operations in buildings ready for a second chance. This time around, a zoned VRF design led to substantial electric and gas savings on top of the rewards of building conservation.
Franklin Energy Services, LLC (Franklin Energy) in Port Washington, WI, has been consulting with utilities, municipalities, and states to create energy-efficiency programs for commercial, industrial, agricultural and residential customers since 1994. The company has offices in 12 states and more than 375 employees.
An example of Franklin Energy’s work is the Focus on Energy program, an outreach effort for more than 10 years with Wisconsin residents and businesses to install cost-effective energy efficiency and renewable energy projects. Franklin Energy worked with Wisconsin’s Focus on Energy business customers in 2011 to save more than 89 million kilowatt-hours (kWh) and more than 1.5 million therms. That amount of energy savings prevented greenhouse gases equivalent to the emissions of more than 13,500 cars.
A Showcase for Energy Efficiency
Franklin Energy moved its 10,000-sq-ft national headquarters into an historic structure on the shores of Lake Michigan in January 2011. The building, which is listed on the National Register for Historic Places, was formerly the Smith Brothers processing plant. According to Franklin Energy Chief Executive Officer, Paul Schueller, the company had always made its headquarters a showcase for the firm’s approach to energy efficiency. The newest headquarters would continue this tradition.
“We have a long history of selecting under-utilized buildings for our headquarters and regional offices,” Schueller said. “Our first Franklin Energy headquarters was in a Port Washington hotel built before the Civil War. We next moved into a vacant church built in 1913. When we outgrew that, we moved into this space in the old Smith Brothers processing plant, the best-known building in town. We like all our offices to be part of the community.”
Planning for his new office space, Schueller called on Randy Mueller of Mueller Heating & Cooling in Saukville, WI, to design the heating and cooling system to control comfort. Mueller had provided sound counsel and several HVAC installations for Schueller over the years, including an installation at Schueller’s home.
CRITERIA POINTS TO VRF
Mueller’s first suggestion was to install a hydronic heat system in the new headquarters, but Schueller rejected the idea as being out of step with his high energy-efficiency goals. They considered a rooftop VAV system but this was impossible with the unique aesthetics that they wanted to preserve. Plus, both a VAV and a cooling tower would add considerable weight to the roof meaning structural support.
Auer Steel & Heating Supply Co. (Milwaukee) is Mueller’s long-time distributor. Mueller and Auer collaborated and concludes that the ideal HVAC solution for this project was a VRF zoning system. Auer was first introduced to VRF zoning technology about seven years ago. It was virtually unknown in the U.S. until the turn of the century, despite enjoying familiarity in Europe and Asia for more than 30 years.
Auer sold its first VRF system in 2005 after staff completed VRF zoning design classes. Staff regularly attend training sessions to keep abreast of the constantly improving technology. According to the company, Auer likes this technology so much that it stages VRF sales presentations at venues around the region.
Auer made the case to the Franklin Energy team about why VRF zoning technology was the best solution for the new headquarters. The system’s recognized energy savings was a top driver, but there were other reasons for the choice: ease of installation, sound attenuation, a great ability for load-sharing (not possible with conventional systems), the small footprint and lightweight modularity of the outdoor units, and exclusive simultaneous cooling and heating technology.
Load sharing and energy efficiency
This results in energy fluctuations and poor set point satisfaction. VRF zoning systems can offer full-range variable capacity to deliver only the amount of conditioned air needed to match a zone’s cooling or heating demand. The compressor seamlessly adjusts speeds to maintain the desired capacity level, working in tandem with system controls and sensors that measure loads for each zone. Loads change as people move about in a building or the sun moves across the building during the day. This function, along with a mainly ductless design, essentially eliminates duct losses that typically equal about 30% in a conventional forced air ducted system.
In Auer’s experience, VRF zoning systems have often wound up 30% to 40% more energy-efficient than conventional HVAC systems while also meeting Energy Star® requirements and achieving the highest Integrated Energy Efficiency Ratio (IEER) ratings. The total applied capacity of these indoor units, for example, can be up to 150% of the capacity of the outdoor unit by taking advantage of load diversity as well as simultaneous cooling and heating.
Why not maximize the heat energy absorbed from the space instead of expelling it outdoors? Some VRF zoning systems offer highly responsive simultaneous cooling and heating performance. The system takes heat energy removed from a zone that’s in cooling mode and applies it to another that calls for heat using a Branch Circuit (BC) Controller. The system runs in its most efficient state by bypassing the compressor.
The Franklin Energy project team was ultimately pleased with Auer’s VRF zoning system recommendation based on these and other factors. The team agreed on a system from Mitsubishi Electric US Cooling & Heating Division (Mitsubishi Electric). The VRF zoning system would serve the perimeter offices (zones), the conference room, and server room. A building’s perimeter demands the largest energy needs. Franklin Energy felt comfortable that a VRF zoning system would be best at matching the building’s space diversity. Auer drew up the schematics and specified the engineering. Due to the north, south and east exposures of this building, the load was going to change dramatically during the day as the sun moved around the building. Even in the colder seasons, some areas would be calling for cooling while others needed heat. Simultaneous heating and cooling with City Multi fit the bill nicely.
Ease of installation and small footprint
Ease of installation is a particularly important factor to consider when retrofitting older, historic buildings like the Franklin Energy headquarters. It was important that mechanical updates cause minimal disruption to the existing structure. This system components are small, resulting in less labor, fewer materials, and easier installation than some conventional forced air options. Compact units can be transported to the floors or the roof via the elevator rather than cranes. The load can be distributed across an existing structure or avoided by mounting on the ground. The benefits all came into play, and Mueller Heating & Cooling finished the installation in January 2011. Franklin Energy moved into its new headquarters at the end of January 2011.
Mark T. Kuntz, P.E., is Mitsubishi Electric’s senior vice president of product strategy and engineering. After a full 12 months of energy usage reporting from the new owners, he had good news.
The design’s energy model was validated using actual utility meter data as well as measured data from an energy monitoring system. The models comparing measured energy intensities for electrical and gas energy were within 1 and 5%, respectively. The expected Commercial Buildings Energy Consumption Survey (CBECS) energy intensity for a building of this age and construction type is 17.9 kWh/sq-ft/yr for electrical and the Port Washington site performed at 12.2 kWh/sq-ft/yr, showing a 32% electrical energy savings for this past year. The gas energy savings for the year was 48% with an energy intensity of 21.9 cu-ft/sq-ft/yr compared to the CBECS expected value of 42.3 cu-ft/sq-ft/yr.
Comfort was still a top priority for Franklin Energy and the people working on site, even though saving a great deal of energy was a top priority.
“Because of the building’s orientation and outdated glass windows, solar gain was a huge issue for our HVAC systems selection,” Schueller said. “This VRF zoning system has been a lifesaver for individual comfort and for helping us save on energy costs. Because of the Inverter technology and individual room controls, the perimeter offices in this old building have been very comfortable in all seasons.”