A Tale of Two Eco-Houses: Net Zero Year-Round Livability in Phoenix

Prototype 1: EcoInn 1

In 2013, Austin Trautman and architect Matthew Salenger (of  CoLab Studio) designed and built an affordable ultra-sustainable house on an infill lot as a prototype for other residences in the Phoenix area. “The home was designed as a contemporary equivalent of the ‘case study’ houses of the 1960s,” Trautman says, “though built for our time and place, and with sustainability in mind.”

The home surpassed LEED Platinum certification. It had a blower test rating of .68 ach50, “which might be a record in Phoenix,” Trautman says. The 1,500-square-foot house uses around 6,000 kilowatt-hours (kWh) (about $700 worth) of electricity per year, provided by a 3.6 kW solar PV system. 

The design of the net-zero house utilized advanced framing techniques to reduce the amount of lumber by 20 percent. The walls were framed at 24" instead of the typical 16". The studs were aligned with the roof trusses, allowing for the reduction in structure.

This approach also reduces heat transfer and increases space for insulation.R Guard on the exterior allows moisture to breathe out, “with the caveat that you have space for it to breathe,” he explains, “so we made our own cladding that mimics the saguaro’s vertical vents, with a one-inch gap between the metal siding and the house, with a vent on the top and bottom.”

The home contains two bedrooms, two bathrooms, an office space, and a spacious great-room open to the kitchen. Large glass doors allow the interior to flow from space to space, and connect the inside with the private exterior courtyard, an outdoor living space screened by slatted metal. A hidden door within the slats is located between the two parking spots.

Siting the courtyard at the front of the lot “solved all of our design dilemmas,” Salenger explained to Builder. “It made sense to put living spaces upfront but I didn’t want a door into a living room, plus there’s some kind of break between living and the street, and the big issue was that an interior courtyard would cost so much more in finishes.”

The team used rusted untreated steel sheets sliced into strips of various widths to create the slats. They computer-modeled gaps in between the metal slats to modulate degrees of transparency that, simultaneously, let breezes through but offer privacy at standing and sitting eye levels. The house, Prototype 1, won numerous awards, including the SRP Sustainable Award and APS Energy Award.

Raichura was smitten. But the house wasn’t for sale. Trautman, by then, had started Vali Homes, with the prototype being used as an Airbnb called EcoInn. Meanwhile, Trautman and Raichura became good friends. When Prototype 1 went on the market again, Raichura bought it. “He’s the perfect owner for a Vali home,” Trautman says. “We really want owners who know what these homes are all about; we’ve kind of created an inner circle of ‘Eco Ninjas’ (what we call our followers).”

Raichura was thrilled to purchase and move into his dream home. “By then, I not only loved the aesthetics but also realized how amazing the house was in terms of high-energy performance,” he says. “The home’s sustainability aspects were a big part of my buying decision.”

Prototype 2: EcoInn 2

By 2016, Trautman, Salenger, and Vali Homes had completed another prototype next door on another infill lot. The all-electric, net-zero solar house has three bedrooms, two baths, and an outdoor courtyard with slats similar to Prototype 1. The second home, Prototype 2, is currently the popular AirBNB, also called EcoInn.

In siting the house, Trautman says, “We asked, ‘What would a native culture do in this climate?’” The team used a low-slope roof with a four-foot overhang on the south, “to heat the house for free all winter,” he says, “and keep the sun off the glass in summer. Tons of south-facing glazing means you never need blinds and can look to the courtyard.”

The house has Windsor windows, Cardinal 366, Low-E and argon filled. “We did double pane windows, which aren’t really necessary in this climate, but they do improve the comfort,” he says. Wood-framed on the inside to aesthetically warm up the concrete floors, provide open plan living, and window expanses; the windows have aluminum cladding on the exterior for durability.