Diverse Home Requires Unique Solution

Challenge:

This 10,000-square-foot design home consists of many zones with various cooling and heating needs. In his previous 8,500-square-foot home, the homeowner used LP gas for heating. With escalating costs of LP gas being the norm, the HVAC designer for H&H Plumbing wanted a more energy-efficient solution for the new home.

A number of unique features, including a sports court with an exercise room, a tanning bed, sauna and steam shower, added to the full-time living areas (master bedroom, guest room, boy’s room and girl’s room suites) required the ability to simultaneously cool and heat.

Solution:

The HVAC designer first considered a geothermal system. However, due to cost, he was looking for an alternative when he attended a Mitsubishi Diamond Designer^™ training class for Variable Refrigerant Flow (VRF) zoning systems from Mitsubishi Electric Cooling and Heating Solutions, Suwanee, Ga. He immediately recognized the Mitsubishi Electric R2-Series’ ability to meet the cooling and heating needs of the 2008 Design Home.

The HVAC designer placed the outdoor condensing unit in the mechanical room on the lower level. By placing the unit indoors, the homeowner can maximize heating efficiency all winter long (an important feature in Michigan). Additionally, the R2-Series is able to cool and heat simultaneously. While heating may be called for in the master bedroom, cooling may be needed for the sports court. Meeting this diversity is no problem for the Mitsubishi Electric R2-Series.

A Lossnay^® ERV unit was installed for bathroom exhaust and ventilation. The entire system is controlled by a GB-50A central controller that allows the homeowner to manage the temperature in all zones of the home both locally and remotely.

When calculating the energy savings the Mitsubishi Electric VRF zoning system can realize over other types of systems, the designer estimated the operating cost of different fuels and system types. Compared to an LP system operating at 92 percent efficiency, the savings of the VRF zoning system are impressive.

Based on a maximum heat loss of 139,000 Btu/hs the estimated annual operating cost of the LP system at $2.45 per gallon was estimated to be $6,414 per year. The Mitsubishi Electric VRF zoning system with an average COP of 3.2 and $.08 per KW will have an estimated operating cost of $1,555 per year. This equals a savings of more than 75 percent.