Amherst Glen by Charis Homes LLC

This Charis Homes project demonstrates how comprehensive electrification can deliver exceptional energy performance, occupant comfort, resilience, and long-term operational savings in a large custom home. Rather than relying on a single high-efficiency feature, the home integrates an all-electric mechanical strategy, renewable energy generation, battery storage, intelligent load monitoring, and a highly efficient building enclosure into one coordinated system.

The 7,834-square-foot home achieved a HERS/ERI Index of -2 with solar, compared with 36 without photovoltaic generation. It is projected to produce more energy than it consumes annually, qualifying it as a Positive Energy Home. The modeled annual energy cost is only $96, with projected annual savings of $12,677 and total annual energy savings of approximately 61,948 kWh. These results are especially significant given the home’s size, four bedrooms, 3.5 bathrooms, and location in Climate Zone 5A.

At the center of the electrification strategy is a four-ton WaterFurnace Series 7 ground-source heat pump. The variable-capacity geothermal system provides efficient heating and cooling without onsite fossil-fuel combustion. It is paired with a four-zone Rheia compact duct system designed for balanced airflow, reduced duct losses, and precise comfort control throughout the home.

The geothermal system also supports domestic hot water production. A geothermal-assisted preheat storage tank supplies tempered water to a centrally located 65-gallon Navien heat pump water heater with a rated efficiency of 4.03 EF. This integrated approach reduces the electrical demand associated with water heating while maximizing the value of the ground-source system.

A 13.28-kW south-facing photovoltaic array is designed to offset 100 percent of the home’s annual energy use. The roof structure and orientation were intentionally designed to support solar installation and optimize southern exposure. A 13.5-kWh Tesla Powerwall 3 provides battery backup, allowing the home to store renewable energy and maintain greater resilience during utility disruptions. A SPAN smart electrical panel gives the homeowners detailed visibility into circuit-level energy consumption and greater control over household loads.

Electrification is supported by a high-performance enclosure that significantly reduces heating and cooling demand. The home includes R-30 above-grade walls, R-60 attic insulation, continuous exterior rigid insulation, a full insulated concrete form basement, high-performance windows, and a blower door result of 1.38 ACH50. A balanced Broan energy recovery ventilator, continuous humidity-sensing bath fans, and MERV filtration provide controlled fresh air and indoor air quality without compromising efficiency.

The project is innovative because every major energy system was designed to work together. The geothermal HVAC, heat pump water heating, solar array, battery storage, smart electrical controls, compact ductwork, ventilation system, and advanced enclosure form a fully integrated electrification platform. The result is a luxurious custom home that proves electrification can support large-scale residential design while dramatically reducing energy use, eliminating onsite combustion, improving resilience, and producing more energy than the home consumes.