A pair of building scientists set out to make their home healthier and more sustainable.

On a lake by the 12th hole of the McCormick Ranch Golf Club, a newly renovated home clad in off-white synthetic stucco and porcelain tile makes more than just an attractive addition to the 50-year-old Scottsdale subdivision. In 2019, two building science consultants bought the old 3,050-square-foot house and spent three years transforming it into a 4,400-square-foot desert contemporary that performs as impressively as it presents.

“The cool thing about this project,” says homeowner and building scientist Steve Easley, “is that it shows you can have a beautiful home that’s also extremely energy-efficient, durable and healthy to live in.”

But like much of the country’s housing stock, at least half of which was built more than 40 years ago, the couple’s home needed a major overhaul. They had intended to do a down-to-the-studs remodel, but when they discovered termite damage, structural problems and plumbing and electrical issues, they decided to start with a (nearly) blank slate.

“Except for one garage wall, we tore the old house down to the slab,” says Susan Raterman, an indoor air quality expert and Steve’s better half. “But we used the same foundational footprint and kept our design plans.”

They also knew the project presented an opportunity to put their professional wisdom to practice. According to Steve, 20% of greenhouse gas emissions are generated by residential structures, and Susan reports that the county has high particulate and ozone concentrations, with a majority of exposure to outdoor contaminants occurring indoors. They wanted a place that would neither pull in pollutants nor contribute to planet-warming gases.

“We wanted to demonstrate that building sustainably, conserving energy without compromising the environment or human health, is not that difficult,” says Steve.

PASSIVE DESIGN AND MATERIALS

It typically begins with orientation. With an almost perfect north-south axis, the homesite lent itself to simple passive energy features, those that account for naturally existing conditions to enhance efficiency.

“Architecturally, we believe you should always take advantage of the simple things first,” says Steve.

For example, overhangs and extended porches on the home’s south and west sides and limited east- and west-facing windows reduce solar heat gain in the summer. Also, a majority of glass on the north and south walls provides for both natural light and passive heating and cooling. And, carefully considered window and door placements enable flow-through ventilation on cooler days.

The choice of exterior materials is also important. Instead of concrete roof tiles that soak up heat all day and radiate it into the attic at night, the couple opted for a metal roof with very low thermal mass that cools much faster.

Porcelain tile was used for the outdoor patio and walkway surfaces. Unlike concrete, the manufacturing of which accounts for about 8% of all greenhouse gas emissions, the tiles keep radiant surface heat to a minimum, can easily be removed if necessary, and help keep rainwater in the ground rather than becoming runoff.

BUILD TIGHT

The couple also adhered to the “build tight, ventilate right” design philosophy, which emphasizes focus on an extremely well-sealed and insulated building envelope with proper, controlled fresh-air ventilation.

A significant component for achieving the first part of the equation was the inclusion of higher R-value insulation and air sealing. The structure includes an inch and a half of exterior insulation behind the stucco to prevent thermal bridging and very high R-value spray foam insulation on the inside walls and roof.
While higher R-value insulation does cost more, Steve says it’s a worthwhile investment that easily pays off: “It’s actually pretty cost-effective because it reduces energy use, thus reducing the number of solar panels required,” he says. “Also with spray foam insulation, you get a 300% increase in wall strength, meaning the walls are much stronger and more wind-resistant.”

VENT RIGHT

To meet the second part of the design equation, the couple incorporated energy recovery ventilators (ERVs) and electric heat pumps.

With technology that pre-cools and pre-heats air as necessary, the ERVs bring in filtered fresh air and recover 75% of the energy required to do so.

“They’re designed to replace stale air in the house with fresh air, and if it’s 110 degrees, the heat exchanger will cool it down to 83 degrees without refrigeration, so we only have to cool it another five or so degrees,” says Steve.

Similarly, electric heat pumps, which transfer heat rather than generate it, are more efficient than furnaces and conventional AC—and much cleaner.
“The concept of electrification is important and means using heat pumps to heat the home in winter and cool it in summer,” says Steve. “It’s like an AC that runs in reverse and allows you to replace fossil-fuel energy with clean, renewable energy.”

PRECISION AND CONTROL

Ceiling-mounted in almost every room, the inverter heat pumps operate at variable speeds precisely and without cooling areas that don’t need it. They eliminate the need for ceiling fans, too, as they blow air quietly in any direction desired. Contrasted with a similar-sized great room area that would normally have 12 large registers sticking out of the ceiling, their electric heat pump cassettes are very discreet.

The home is also equipped with air quality sensors in each of the living areas and bedrooms. These not only help precisely control the amount of fresh air entering the home, but also automatically monitor air quality for carbon dioxide levels, VOCs and particulates.

“A primary goal,” says Susan, “was to go from a house that used natural gas for heating and cooking to one that reduces greenhouse gas emissions and eliminates indoor toxic emissions generated by gas.”

As for overall energy efficiency, the home raises the bar for the neighborhood—and for Phoenix.

“Even though the house is now a third larger than what it was, our current energy consumption is less than half of what it had been,” says Steve. “And when we install our solar system this fall, we’ll be at zero, meaning our home will produce as much energy onsite as it consumes from the grid.”

SOURCES

• Architect: Edward Chavez, Chavez & Associates, Phoenix, chavezaia.com.
• Builder: Steve Easley, Steve Easley & Associates LLC., Scottsdale, steveeasley.com.
• Interior designer: Edie Stockstill, Stockstill Designs, Scottsdale, stockstilldesigns.com.
• Landscape designer: Phil Shearon, Shane Turner, Shearon Design Collective, Scottsdale, shearondesignco.com.