WaterFurnace Geothermal Systems are
an Energy-Saving Plus for “Net-Zero” Homes
Objective: Reduce space heating, cooling and domestic hot water costs in efforts to create a net-zero home that is reliable and comfortable throughout the year.
Home Size: 3,000 Square Feet
Unit Type: Envision 4-ton
Number of Units: 1
Loop Type: Vertical
“Net-zero-energy” (NZE) or “zero energy” residential construction combines advanced building materials and techniques with energy-efficient appliances and comfort systems to achieve significant energy reductions. Then it goes one step further by employing solar technology, such as photovoltaic solar panels, to power the home. As a result, a NZE home sells electricity back to the utility, zeroing out energy expenditures over the year and even creating a positive cash flow for the homeowner.
The Net-Zero Goal is within Reach
To reach that net-zero goal, however, a home’s biggest energy hogs must be put on a serious diet. In the typical American home, space heating, cooling and domestic hot water productions consume 68% of the total energy budget. “The good news is that you can achieve high-efficiency practices with current technologies,” says net-zero homeowner David Shepler. “Heating and cooling equipment is available that can help you reach net-zero today.”
“Every high-performance home takes advanced planning. We want to get everything working together as a building system, not just a comfort system.”
Shepler’s 3,000-square-foot, 3-story NZE home in New Paltz, NY, was built by Anthony Aebi of Greenhill Contracting. His “Green Acres” development is the first single-family NZE residential development in the nation, with five single-family NZE homes sold and occupied. Shepler’s home incorporates a 10-kilowatt (kW) solar photovoltaic (PV) system along with a tight building envelope, heat recovery ventilation (HRV) system, insulating concrete form (ICF) construction, structural insulated panels (SIP) in the basement, and 12-inch spray-foamed rafters. The mechanical and PV system were specified and installed by Hudson Valley Clean Energy. “We did a load analysis of all the appliances and mechanical equipment,” says John Wright, VP for Hudson Valley. “Every high-performance home takes advanced planning. That’s especially true with a NZE home. We want to get everything working together as a building system, not just a comfort system. Then we remotely monitor energy consumption to confirm the savings.” The comfort system included a WaterFurnace Envision two-stage, 4-ton heating and cooling system with desuperheater and low speed fan. The system’s heating Coefficient of Performance (COP) is 3.64 at 30°F, and the cooling Energy Efficiency Ratio (EER) is 17.0 at 80°F. This compares to 2.25 COP and 10.65 EER for a typical 18 SEER heat pump. The additional energy savings made it possible for Shepler to exceed his net-zero goal, who notes that “measuring from March 2009 to March 2010, I actually produced 1,700 kW more electricity than I used.” Building science is not understood or accepted by most in the construction industry. It is easy to design a NZE building but very hard to actually have one. The design, construction and operation must be nearly flawless in order to succeed.