VRF System Delivers Total Tenant Comfort

Mixed-use complex integrates VRF and water-source geothermal system for energy efficiency.

The Mill at Dover-Foxcroft, ME, is a 60,000-sq.-ft. mixed-use building complete with residences, office space, a café, and a boutique inn.

Located on the picturesque Piscataquis River in Maine, The Mill at Dover-Foxcroft is a 60,000-sq.-ft. complex that comprises nine structures built between 1841 and 1944. After sitting vacant for nearly a decade, Arnold Development Group, Kansas City, MO, embarked on a full renovation of the complex to develop a mixed-use building complete with residences, office space, a café, and a boutique inn.

On the National Register of Historic Places, the renovation of The Mill required an update to modern amenities with limited modifications of the building’s envelope. In addition to the preservation of the structure, the developer also wanted to make the building a net-zero facility in the future with plans to restore the turbine of the pre-existing hydroelectric dam.

Located 100 miles from the Canadian border, where during the winter months the temperature can frequently sustain below-freezing temperatures, the new HVAC system needed to provide year-round comfort. Along with functioning in the extreme conditions, in order to achieve the desired net-zero impact, the system needed to be energy efficient while still delivering on the specific comfort requirements of the varying businesses operating throughout the complex. All of this had to be achieved with minimal modification to the structure in order to preserve its historic nature.

A predominantly duct-free solution, the LG VRF small-refrigerant piping was minimally invasive to the building’s envelope.

A robust solution

After evaluating the needs of the project, Ranor Mechanical, Jay, ME, recommended Englewood Cliffs, NJ-based LG’s Water Source VRF system for The Mill. The robust solution uses 180 tons of Multi VTM Water IV heat-recovery units that tie into the geothermal well system and include a variety of indoor units, such as ceiling cassettes, wall mounts, and high-static ducted and floor-standing indoor units. By implementing a predominantly duct-free solution, the small refrigerant piping was minimally invasive to the building’s envelope. The design flexibility of the LG VRF solution allowed the appropriate mix of indoor units to be used to meet the comfort and aesthetic requirements of each space.

In addition to the space savings from eliminating the need for bulky ductwork, the condensing units themselves are substantially smaller than a conventional system. With a small and compact footprint, the Multi V Water IV units were installed in the mechanical room under the building. This placement not only serves to make the units unobtrusive, but also allows easier control of the temperature from the source water loop that enables the system to effectively heat in the extreme temperatures.

The design flexibility of the LG VRF solution allowed the appropriate mix of indoor units to be used to meet the comfort and aesthetic requirements of each space. Multi V Water IV heat-recovery units tie into the geothermal well system.

One of the key requirements of the new system was energy efficiency. With future goals of creating a net-zero building, The Mill management chose to maximize efficiencies by implementing the company’s water source heat-recovery units that tied into nine, 1,000 ft. geothermal wells. The Multi V Water IV units were easily incorporated to the geothermal well system and use water control valves to regulate the operating pressure to the VRF units for improved efficiency. Heat-recovery units were selected for the mixed-use complex due to the varying temperature demands across the spaces. By choosing a heat-recovery system, The Mill HVAC system is able deliver simultaneous heating and cooling while balancing the comfort demands of the occupants. This not only allows excellent comfort and maximizes the energy efficiency, but it also lowers the operating costs and eliminates the need to have a secondary system to supply heat.

By only using small piping rather than traditional, large ductwork, the Multi V Water IV system seamlessly blends into the building’s interiors without disrupting the exterior. The architectural integrity of the historic mill complex and compliance with the guidelines set forth by the National Register of Historic Places were both met with no issue. In recognition of this accomplishment, the architect was awarded Maine’s Historic Preservation Honor Award for Stewardship in 2015.


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