This article is part of a continuing series on sustainable remodeling projects from across the country.

The Castaway House, the first project certified by the Phoenix Green Construction Code, revitalized a 1,000-square-foot stripped and abandoned 1951 house while adding a 970-square-foot addition, all for under $100 a square foot.

The redesign focused on overcoming the desert city’s three major sustainability challenges—intense heat, water shortages, and sprawl. The project team started with the building envelope, which combats the harsh sun and summer heat through a variety of methods, including an innovative vented wall and roofs that focus on controlling thermal transfer. On top of the original roof, workers added an R-9 low-E radiant barrier, reclaimed and treated 2x6 furring strips to provide a vented air gap, a new roof deck with Owens Corning Deck Defense high-performance roof underlayment, Energy Star-labeled cool roof shingles, and a rigid roll ridge vent with moisture barrier. The vaulted ceiling was then sprayed with 5.5 inches of closed-cell spray foam.

An overhang on the south was extended three feet to eliminate direct sunlight on the existing portion of the house from April to October. The project team filled in existing windows on the east and west of the block structure and added 1.5 inches of foam insulation boards using existing studs as furring strips.

With ample glazing in each room, the house requires minimal artificial light, and even areas without windows, such as the bathrooms and master closet, include 10-inch Solatube tubular daylighting devices. The L-shaped floor plan, with bedrooms on the east and living spaces on the west, maximizes cooling cross breezes and Energy Star-labeled ceiling fans help keep interiors cool.

To keep costs down, architectural designer Cavin Costello of the Ranch Mine incorporated many of the original home’s finishes and materials in the renovation and addition. The existing concrete patio was broken down and reused as front yard pavers, interior studs were repurposed for new framing and furring, and metal pipes were salvaged for closet rods. The only intact window from the original home was used on an interior wall to add character and to increase natural daylight and ventilation.

New interior products were carefully selected for their contribution to air quality, including Cohills water-based flooring stain; Sherwin-Williams Duration low-VOC paint; Greenguard Children & Schools-certified kitchen cabinets from Executive Cabinetry; and zero-VOC custom countertops made locally from recycled glass, mirrors, and salt river rock salvaged from terrazzo flooring manufacturing.

Costello says that another major design goal was to increase the home’s lifecycle by providing the homeowners with the ability to age in place, or to comfortably house aging parents if needed. Universal strategies included removing kickplates under the kitchen sink and island for wheelchair access; providing support in the bathroom walls for future grab bars; specifying user-friendly fixtures, pulls, and door levers; and including turning radii and floor transitions necessary for accessible living. The site was graded to be wheelchair accessible.

To help conserve water, the low-maintenance desert landscaping is designed and graded to drain into 6-inch recessed planting beds that are zoned by varying water demands to harvest site rainwater. All the rainwater from the roof is collected into two 550-gallon tanks uses the stored rainwater, when available, to irrigate plants through drip emitters.

Other sustainable features include: --Whirlpool Energy Star-labeled water heater with inline hot water recirculation pump
--WaterSense-certified Kohler faucets and showers
--WaterSense-certified 1.28-gpf toilets
--2x6 wall framing spaced 24 inches on center and prefabricated trusses
--Low-E, argon gas-filled Milgard windows and sliding glass doors
--Greyfield site less than 0.25 mile from public transportation
-- Low-water trees located in front of western and southern windows for shade