Located on the Piscataquis River in Maine, The Mill at Dover-Foxcroft is a 60,000-sq-ft complex comprising nine structures built between 1841 and 1944. After sitting vacant for nearly a decade, Arnold Development Group 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 desired to make the building a net-zero facility in the future with plans to restore the turbine of the pre-existing hydroelectric dam.

Since it would operate 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. On top of functioning in the extreme conditions, in order to achieve the desired net-zero impact, the HVAC 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.

After evaluating the needs of the project, Ranor Mechanical recommended LG’s Water Source VRF system to The Mill at Dover-Foxcroft. The solution featured 180 tons of LG Multi VTM Water IV Heat Recovery units that tied into the geothermal well system and included 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 VRF solution allowed for 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 units were installed in the mechanical room under the building. This placement not only serves to make the units unobtrusive but allows for easier control of the temperature from the source water loop, which enables the system to effectively heat in the extreme temperatures. 

One of the key requirements of the new system was energy efficiency. With future goals of creating a net-zero building, The Mill chose to maximize efficiencies by implementing LG 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 used 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 is able to deliver simultaneous heating and cooling while balancing the comfort demands of each occupant across the building. This not only allows for comfort and energy efficiency, 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.

“The energy-efficient LG Multi V VRF system met all criteria with flawless performance, and it tied in perfectly with the geothermal wells to generate big cost savings and improve energy efficiency,” said developer Jonathan Arden. “The Mill has retained its architectural integrity and was honored to remain on the Historic Register and receive a prestigious Stewardship award. All of our various tenants and customers, whether living at The Mill, working in the office space or enjoying coffee at a café located on-site, are comfortable and happy, even in the coldest winter months in Maine.”