Over the course of 15 days in Marana's Solara subdivision, Meritage Homes built a super high-efficiency, partially "deconstructed" learning house that allows guests an up-close look at the most energy-frugal homebuilding techniques and technology on the market.
Its attic is exposed, its walls unfinished, its plumbing and heating, ventilation and air conditioning systems right there for all to see.
The house has estimated lighting, heating, cooling and water utility expenses up to 75 percent less than comparably sized, traditionally constructed homes. It has become Meritage's new standard in the subdivision off Moore Road.
Jeff Grobstein, desert region president of Meritage Homes, was eager to "share our excitement" during a Sept. 2 "open house" event.
"This is a new era, not just for Marana," said Grobstein, who credited the Town of Marana and Tucson Electric Power for their help in "enabling builders to bring in a super high-efficiency home, and make it affordable." While the efficiency investments cost $50,000, rebates and incentives help make the homes similarly priced to less-efficient houses.
"Cost to the homeowner? Zero," Grobstein said. "It's all about helping the environment, and helping people to afford the home."
A 1,565-square-foot, three-bedroom Meritage model has estimated annual energy expenses equivalent to $596 a year — less than $50 a month — according to a Bright Solutions audit by Tucson Electric Power. A similar new house built to code might require $1,467 in annual energy expenditures; the average resale home, $2,197 a year.
"If people can spend a couple hundred dollars less on utilities, they can buy a bigger home, or a home is more accessible," said Marana Mayor Ed Honea.
Dan Hogan of TEP has been certifying energy-efficient homes for 14 years.
"This, by far, is the most energy-efficient homes we have done," Hogan said. "It's almost scary from the utilities' standpoint, they use so little energy. It's never really been done in a production environment like this."
C.J. Herro, Meritage's vice president of environmental affairs, travels the country for Meritage to talk about energy-efficient housing. He said the Solara homes are "more energy-efficient than any houses built in the U.S. This is the most recent evolution in potential homebuilding today."
Inside an energy- efficient house
How does a super high-efficiency home, such as the models Meritage Homes is building in the Solara development in Marana, use so much less energy than a standard home?
There are many reasons. Computerization gives the house its own "brain," and enables systems to work in synchronization.
For examples …
• The home's solar energy systems create hot water, hot air and cool air as needed. Solar panels heat water, and those panels also generate electricity to … heat water. There is an oversized, 120-gallon water heater to store "free thermal energy," according to Meritage's C.J. Herro, vice president of environmental affairs.
A typical family of four might spend $170 a year to heat water; in the Meritage houses, that family would spend $3 per year to heat water.
• Those rooftop solar panels lie flat, rather than at an angle. There is space beneath the panels and the rooftop, allowing air to flow that cools the panels and makes them more efficient. That below-panel space, built to let air flow but keep rodents and bugs out, also holds cool air at night. When the homeowner calls for cool air, the first place it comes from is beneath the panels, rather than from an air conditioning unit. Likewise, if there's heat on the roof and the homeowner calls for heat, it's pulled in from the roof first.
The home's air conditioner and heat pump save up to 40 percent of the energy used by a system 10 years old. A programmable thermostat can yield up to 30 percent savings in cooling and heating costs.
• The irrigation system is attached to a rain sensor, so that if there's moisture falling from the sky, there's less water flowing from irrigation lines. The outside turf is artificial, and all the landscape plantings are heat- and drought-tolerant.
There is no swimming pool at one of the Meritage houses; instead, a circular concrete pad has variable height fountains, consuming less water but still cooling hot people. Low-flow faucets throughout the home can cut water consumption in half; dual-flush actuator toilets can reduce water use by 70 percent. In sum, a family of four would get all the water it needs with half the estimated water consumption.
• High-performance windows are low-energy, keeping heat out and moderated air in. The homes are sealed tight. Spray-foam insulation in walls, ceilings and the attic creates "an air barrier," Herro said. In a normal house, air might be exchanged completely with outside air twice per hour. In these houses, air exchange is less than 10 percent in an hour. Summer attic temperatures in a typical Arizona house can reach 160 degrees; in the Meritage house, those attic temperatures are near 80.
• Light bulbs are compact fluorescent lights, using 75 percent less energy and producing 25 percent of the heat of standard light bulbs with up to 10 times the life of a standard bulb.
• Appliances are low-energy "Energy Star" certified.