Other developers boast building communities of solar homes, but Austin, Texas-based architect, developer, and builder David E. Martin says the homes in his Las Casas Verdes development are solar homes in the truest sense of the word.
“Without being negative sounding, solar panels on a tract, non-site-specific home does not make it a solar home,” says the president of D. Martin Homes. “A true solar home is one that is designed for both passive and active solar.”
Las Casas Verdes is a subdivision of homes located on about three acres in southwest Austin. The builder says that, unlike many other developments that simply add green features after the fact, the homes are designed and built green from the ground up with one goal in mind: to conserve energy and lower your utility bills. “Our homes are individually designed for both the specific site and the buyers design input,” Martin says. “The key feature is the inclusion of passive features. Every window, the location and number of windows on a particular wall, and its coverage by awnings, overhangs, or porches is determined during the initial design phase.
“Our homes control the sun in the summer months by not allowing any direct sunlight to strike window glass,” Martin continues. “However, we use the sun in the winter months by allowing as much sun to hit those same windows, thus heating the inside of the house.”
Homes feature a design that the architect calls Texas modern craftsman, with two-story interiors and abundant natural light. The base home measures 1,800 square feet and includes three bedrooms and two and a half bathrooms, but the homes may be larger and have different configurations—including four bedrooms or two masters.
The homes use a foamed finger jointed wood stud wall and structural-gauge metal stud roof panels in modules of 2, 4, or 6 feet. To help keep costs low, every window in the subdivision uses the same two sizes in various groupings of one, two, or three units.
Though the homes are designed for their lots, each one includes a 3-kilowatt solar photovoltaic system as a standard feature. “The roofs are sized to allow for doubling the system size,” Martin explains. “During the winter months, we are seeing electric bills as low as $4 with an average bill for the year of $35. During the summer months, we are seeing an 80% reduction in our bills as compared to homes of similar size.”
In addition to the solar PV, the homes also include solar thermal panels for water heating; passive solar design, including deep roof overhangs, awnings, and porches; a high-SEER multi-zone HVAC system including pressure-tested and sealed air ducts within the home's thermal envelope; and heat chimney with operable windows to move air and ventilate the home. Heat-recirculating ducts reuse pre-heated air in the winter, and multi-speed fans and duct controllers cool (or heat) specified portions of the home.
The homes also includes the prerequisite green highlights such as rainwater collection systems for use in toilets and irrigation, no-VOC paints, reflective metal roofs, and recycled building materials. As a result of the features, the development’s model home has been awarded a 5-Star rating from the Austin Green Building Program and a 5-Plus Star rating from the federal Energy Star program.
The homes are priced from $350,000 to $385,000 before federal tax credits for energy features.