Unique Challenges

For La Crosse, Wisconsin, homeowner Mike Lemmon, comfort and energy savings were the top priorities when it came to retrofitting his Federal-style, wood-frame home, which was built in 1904. Located on a standard city lot, the 3,500-square-foot home was originally heated by a coal-fired gravity furnace before being converted to convector radiators, which were initially supplied by district hot water. Around 1946, that service was terminated, and then-homeowner Reuben Trane, founder of the Trane Co., installed a gas-fired boiler, which remained in service until 2012. Central air conditioning was added in the 1960s or 1970s.

While the existing boiler provided adequate heat, it was noisy, and Lemmon grew tired of the high gas bills, which often exceeded $1,100 per month. The air conditioning worked well, but the equipment was old, the ductwork was improperly installed, and the upstairs bedrooms lacked returns. He became interested in replacing his existing equipment with a geothermal system and turned to Mark Flock, president, Flock’s Heating and Air Conditioning, Cashton, Wisconsin, for help.

Flock found that the home posed some unique challenges, the first of which was figuring out how to continue utilizing the original convectors that were designed for 180°F water. Current heat pump technology lacked such a solution. Thinking outside the box, he designed a system that combined a WaterFurnace 5 Series high-temperature water-to-water heat pump capable of 150? output with a WaterFurnace HydroZone controller with outdoor temperature reset, which would provide longer, steadier run times. “I then added a 90 percent efficient Weil-McLain boiler to boost the temperature to 180° when needed and tied that in with the outdoor temperature lockout.”

The geothermal unit is capable of providing 100 percent of the home’s heating needs until outdoor temperatures drop to 10°, at which point the gas boiler turns on to supplement the system. If temperatures reach minus 20?, the boiler, along with the outdoor temperature reset, gradually boost the output temperature up to 180?.

The cooling system consists of a WaterFurnace Envision water-to-air unit, which provides additional heat for the home and is the only source of heat for the third floor. Flock replaced all the ductwork, added individual returns to each of the bedrooms, and zoned the home with Honeywell RedLINK™ Wi-Fi thermostats on each level. An Aprilaire high-efficiency air cleaner rounds out the system.

One additional challenge Flock faced was figuring out how to install a loop field for a house with a small front yard and no backyard that sat very close to its neighbors. He ended up designing a vertical bore loop field that was drilled between Lemmon’s home and a neighboring home, with five 250-foot-deep bores that were 15 feet apart.

“In order to get the drill rig in place, the drilling contractor had to build earthen ramps from the street, across the sidewalk, and into the yard,” said Flock. “The five loops were headered together 7 feet below the surface and enter the home just above the floor. After pressure testing and backfilling the header pit, a landscaper was brought in to re-sod the yard, and a couple of weeks after completion of the loop field, you would never know we had been there.”

It cost about $45,000 to install the new HVAC systems, but Lemmon could not be happier. “There has been a 40 percent savings in cooling and a 20-30 percent savings in heating. The next phase of the project will include variable-speed pumping on the source side, which will add even more savings. But, as for comfort, it has exceeded expectations in both cooling and heating.”

Certified Home Fulfills Wish

Currently on the market in Highland Village, Texas, is a net-zero energy house that demonstrates how to build a high-performance, energy-efficient, healthy home. The Village Park Eco Home uses sustainable and recycled materials to reduce the impact on the environment, and it has been certified as a U.S. Department of Energy (DOE) Challenge Home, Energy Star Home, and Green Built Texas Home. It also features a specially designed bedroom inspired by Cassidy, an imaginative 9-year-old Make-A-Wish® North Texas recipient whose wish is to be a zookeeper.

The home was completed in April 2014 and features 3,278 square feet on the first floor and a 474-square-foot bonus room on the second floor. Obviously, energy efficiency was a main concern for the home, but comfort and proper IAQ were high priorities as well. Keith Wolverton, president, Wolverton Air, Waxahachie, Texas, who designed the HVAC systems for the new home, set out to accomplish all these goals.

After calculating the Manual J for the home, Wolverton found that it required 3.12 ton of cooling, so he specified a 4-ton inverter-driven Frigidaire heat pump. “We were looking for a unit with a variable-volume refrigerant compressor, and this heat pump will modulate the capacity 49-118 percent in five steps to match the load of the home, providing more even temperatures and humidity while saving energy.”

In addition, the system will achieve ratings up to 19 SEER and 10 HSPF when matched with a variable-speed indoor air handler, which was an important factor for this home. Wolverton has been involved in the construction of several net-zero energy homes, and he notes it is critical to make sure the equipment is as energy efficient as possible. “We always try to minimize the startup draw from the compressor to help reduce the amount of solar panels needed, and the inverter-drive compressor makes that easy.”

To ensure comfort, Wolverton installed a three-zone motorized damper system with programmable thermostats, so the owner can regulate the temperature in each zone of the home individually. “The ComfortPlenum™ with XCI damper board is designed with the dampers and motors already installed in the plenum, making for a very clean and air-tight installation. It also complements the variable-volume heat pump very well.”

Fresh air exchange is achieved with the help of an Aprilaire Model 8126 ventilation control system, and a 4-inch MERV 11 media filter improves IAQ. “We also sealed all the duct openings during construction to keep any dust and debris out of the duct system until the home was completed,” said Wolverton.

While most of the materials were donated for this $689,000 home, Wolverton estimates that the HVAC systems would retail for about $19,500. “This project went pretty smoothly, and we are happy with the end result.”

Sustainable Dream Home

Lisa and George Vail moved to Atlanta from Los Angeles in 2006 with dreams of building an energy-efficient, sustainable home that was perfectly tailored to their family’s needs. Finding the right property took some time, but when the Vails discovered the perfect 1/4-acre wooded lot in 2011, they knew the time was right to start constructing their dream home.

The Vails turned to architect Jordan Williams, partner, Plexus r+d, Atlanta, to design a contemporary dwelling that would follow the guidelines of the EarthCraft House Program, a green building certification program that addresses factors impacting homes in the Southeast, including high heat, humidity, and temperature swings. Homes and businesses certified through the EarthCraft program must meet a number of criteria that ensure sustainable, efficient design and functionality.

After researching numerous options, the Vails determined that a conventional ducted HVAC system would not satisfy their energy and sustainability goals, so they chose a ductless zoning system they felt would best meet their cenergy-efficiency, comfort, and IAQ needs. “The ductless system was a great choice for this home because we were able to eliminate all the ductwork that typically runs above the ceiling in the house, which allowed us to decrease the height of the house by about 2 feet,” said Williams. “It also helped us achieve EarthCraft certification much faster, because the contractor did not have to test the ductwork for leakage.”

The Mitsubishi Electric ductless system chosen for the home was installed by Pat Hayes, president, Air Conditioning Specialist Inc., Covington, Georgia, who said the system’s extremely low energy consumption and highly versatile zoning capability made it a perfect fit for this home. “Plus, it has the ability to heat the house down to a very low temperature without needing alternative sources for heating.”

The Vails appreciate the independent temperature control they have in their home, as they have the ability to change the temperature based on personal needs. And having five zones means they only have to heat or cool spaces that are occupied, which results in significant energy savings. In fact, the energy bills for this 2,700-square-foot home average about $75 per month, which is approximately 43 percent less than the average home in Georgia.

Also contributing to the energy savings in the home are 6-inch walls with R-60 blown foam insulation (R-70 in the roof); a high-efficiency tankless water heater; an energy recovery ventilator (ERV); an Energy Star advanced lighting system; and a photovoltaic array on the flat roof membrane for power.

“We knew we wanted an energy-efficient, sustainable house that fit our values,” said Lisa Vail. “We ended up with the exact home we wanted — it is everything we dreamed of to raise our family in.”

Publication date: 6/23/2014 

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