The Mitsubishi VRF zoning system includes important core features for hotels, such as superb individual room controls, dehumidified indoor air and indoor fan coils that are extremely quiet.

Hotel Indigo Athens is located five blocks from the University of Georgia in the historic city of Athens, Ga., 75 miles east of Atlanta. One of 33 upscale boutique brand hotels developed by InterContinental Hotels Group (IHG), it is one of only five in the nation to achieve LEED Gold status. It is also the first LEED Gold certified hotel in IHG’s extensive portfolio of 4,500 hotels in 100 countries and territories around the world.

The property was developed by Atlanta-based Rialto Partners LLC and is managed by Park Place Hospitality Group, Charlotte, N.C. Rialto selected the Hotel Indigo brand because of its guiding principle that each hotel embody the vernacular of the local community. In contrast to the typical hotel chain property, no two Indigo hotels can look alike.


Being a one-of-a-kind hotel was not the only goal for this building endeavor. Sustainability was a key focus as plans proceeded for the hotel’s construction. To ensure LEED Gold certification in compliance with the LEED-New Construction guidelines, Rialto engaged Melaver Inc., a Savannah, Ga.-based consulting firm best known for its expertise in sustainable development.

Recycled and locally manufactured materials were utilized in the building’s construction and all guestroom furniture was sourced from a regional manufacturer within 500 miles.

Additional green innovations included a regenerative elevator, low-flow plumbing fixtures, an outdoor water cistern that collects condensation from the air conditioning system to supply irrigation to courtyard foliage, and a variable refrigerant flow (VRF) zoning heating and air conditioning system.

“HVAC efficiencies and controls played a critical role in achieving high levels of LEED certification,” said Tommy Linstroth, Melaver’s director of sustainability. “The VRF zoning system from Mitsubishi Electric Cooling and Heating Solutions helped us on many levels. The energy efficiency of the system and the ability to capture waste heat helped contribute to our energy credits, while the high degree of controls available helped us earn points for user comfort.”

Among other features, the product also provides the ability to control the guest room temperature from the front desk allowing hotel staff to keep the systems off when rooms are unoccupied and condition them when guests check in.

Recycled and locally manufactured materials were utilized in the building’s construction and all guestroom furniture was sourced from a regional manufacturer within 500 miles.


Equally impressed with the Mitsubishi system was Tim Gilbert, PE, CxA, LEED AP, principal-in-charge for HESM&A Inc., Atlanta. The company was introduced to this high efficiency HVAC system by the sales team from Dean Long & Associates and Mingledorffs of Atlanta.

“This is a great application to use when a building needs to have the high efficiency required to earn multiple LEED points,” said Gilbert. “To meet LEED requirements, a building must improve the overall energy efficiency at least 14 percent above the International Energy Code (ASHRAE 90.1 – 2004). The Mitsubishi Electric VRF zoning system along with the building’s north-south orientation, high efficiency glass, and building insulation components combined to far exceed this requirement. This resulted in a 21 percent improvement in energy performance over the baseline of ASHRAE Standard 90.1-2004.”


According to Michelle Robb, LEED AP, vertical markets/an- cillary product manager for Mingledorff’s Inc., Norcross, Ga., “Mitsubishi Electric’s VRF zoning system contributed points in the Energy & Atmosphere and Environmental Quality sections for LEED. The ability of this system to utilize waste heat to condition space of opposing needs, along with its unique inverter technology, provided the ability to size the system based on individual zone needs.”

According to Mitsubishi Electric, this reduces the overall size of the system while not impacting occupant comfort. The inverter constantly varies the amount of energy used to meet the individual zone needs.

“Individual zone control is also a part of the LEED process,” said Robb. “The VRF system is controlled by the front desk for occupied/unoccupied status. Once occupied, the system allows occupant control while providing setback/setup during unoccupied times. The system also provides data logging for assistance with commissioning systems and re-certification of comfort controls throughout the life of the system.”


“In addition to the significant, core qualities of the VRF zoning system - superb individual room controls and the extreme quietness of the indoor fan coils - we made every effort to create a very clean design environment for the individual rooms, hallways, and public areas,” pointed out Dennis Hertlein, partner at the architectural firm of Surber Barber Choate & Hertlein, Atlanta.

“The Mitsubishi system improved all these spaces with outstandingly clean, filtered IAQ and air movement. Beyond this, we specified a chrome linear air diffuser grille attached to the indoor fan coil supply duct. It is a stylish way to deliver the conditioned and dehumidified outside air that is mixed into each guest room HVAC unit via the HVAC energy recovery unit system.”

Anna Ferretti, LEED AP, Rialto’s director of operations and development described the hotel’s other sustainable elements. These included a better building envelope to reduce heat gain; low-E windows; spray foam insulation; 1 gpf toilets; low flow faucets; and low-flow shower heads standard in every guestroom. The energy recovery unit system that ensures that outside air is introduced throughout the building’s HVAC system is an important energy-efficient element. Ferretti said the hotel is over 30 percent more water efficient and over 20 percent more energy efficient than code.

Publication date:02/28/2011