Mark Matson For the Chronicle
Native trees and flowers surround the Austin home of Laurel Treviño and Carlos Torres-Verdín. The home received a Platinum rating from the U.S. Green Building Council and a 5-star rating from Austin Energy's Residential Green Building Program.
Tonalacalli: The House of Sun and Water
The modern Texas ranch home of Laurel Treviño and Carlos Torres-Verdín is perched on 10 acres in southwest Austin. Cosmo and Quinoa, the couple's dogs, like to patrol the courtyard out front.
Treviño and Torres-Verdín live in Austin's first LEED Platinum house, the greenest rating a home can receive from the U.S. Green Building Council.
All of the couple's water comes from rain that is collected in gutters along the metal roof and sent to tanks that can hold up to 21,000 gallons. A solar water heater heats what they use in the house.
At least 80 percent of the home's electricity comes from solar panels affixed to the metal roof. "We're hooked up to the grid," said Treviño, explaining that they do rely on air-conditioning in the hotter months. But during the day when the air-conditioning is off, the meter runs backward and the home feeds energy back into the grid. The most the couple have paid for electricity is about $80, in July. The least: $10 or $12 in the cooler months.
Houston architect LaVerne Williams designed the home to conduct the Hill Country breezes that blow in from the southeast. On the southern side — the front — the windows are low. Cool air blows in through these windows and circulates into the main living area. When the back windows are open, the couple gets a soothing cross-breeze in the heart of the home. Small windows placed high along the back of the second story pull the warm summer air up and out.
The upper part of the 3,000-square-foot home is built from Hardiplank, a weather-resistant fiber-cement siding. The bottom is made of Hebel concrete blocks, which are light and, with proper finishing, help moderate moisture in the house.
The floors are a hodgepodge of cork, Marmoleum, tile, stained concrete and bamboo. All the interior walls are painted with Bioshield clay paint, and the inside of the exterior walls are topped by natural clay plaster. Austin musician and sustainable builder Frank Meyer mixed the plaster onsite and fashioned a dramatic adobe and cob fireplace that runs up behind the wood-burning stove.
"It's an extremely healthy home," Williams said. "As far as materials go, 90 percent have no man-made chemicals."
Treviño, a medical translator, recalls a modest ecohouse that she visited in the 1970s near Mexico City, where she grew up. The homeowners collected rainwater, used geese droppings for fertilizer and produced their own bio-gas from cow dung. Since then, Treviño has always wanted to build green.
When she and her husband moved to Austin from Buenos Aires in 1999, they found themselves in a city with a green building program. A few years later they went on a Cool Homes tour and saw some green homes up close. That's when Torres-Verdín, a University of Texas professor and associate chair of the Petroleum & Geosystems Engineering Department, got interested in the engineering aspects of green homes.
Treviño is quick to praise her husband for seeing the house to completion. It took 18 months to build, but nearly four years to secure the land, loans, architect, builder and materials.
Working closely with Williams and the builder, Custom Building, Inc., of Austin, the couple was able to use mostly Texas materials in the home, including juniper, cedar and post oak from their own property. The staircase railings are made from juniper trees that Treviño and Torres-Verdín cut down themselves.
Treviño loves the medley of wood, clay, and earthy aromas in her house. "There are no harsh smells," she said.
She named the home Tonalacalli, which means House of Sun and Water in Nahuatl, an ancient language spoken in central Mexico.
"I'm very content and happy here," Treviño said. "Because of all the clay and earth tones, it's a very soothing, grounded house."
When David Ronn set out to build a new house for his family, he had a few major requests.
The corporate securities lawyer told designer Kathleen Reardon that he was looking for whimsical and fun. He explained that he and his wife, financial planner Ann Baker Ronn, were "a little bit nutty."
Ronn also wanted energy efficiency, something the family's current Memorial home did not have. And he wanted to level the existing house and rebuild on the same lot.
The Ronns hired GreenHaus Builders and — after 17 months of construction — moved into their new 4,200-square-foot home on Memorial Day 2007. Theirs is the only home in Houston to be LEED certified by the U.S. Green Building Council; the Gold rating reflects the home's materials, energy efficiency, use of solar power and more.
Informal gardens flush with native plants frame the house. A metal roof reflects heat from Houston's brutal sun. The home's skirt is made of limestone quarried in Austin, and its exterior walls are made of stucco laid overtop ICF — insulating concrete forms. Michael Strong, of GreenHaus builders, credits ICF for much of the home's resistance to heat.
"It's cool, quiet, safe and tight," Strong said.
Inside, the Ronns have created a comfortable, informal space. No plastic slipcovers here. "Part of the planning was to try and make every space in the house functional, so there wasn't a guest room you throw stuff in or a closet you don't need," Ronn said.
Reardon also tapped into the family's sense of fun. She designed an indoor slide for the kids and a music/family room outfitted with a recording studio, where Dad practices with his band, Plastic Farm Animals.
"We also use the music room as a dining room," Ronn said. "We held Passover in there. We've had dinner parties in there. Part of green is multifunctional rooms."
Underfoot, ecoflooring includes bamboo and recycled rubber. The Ronn house also boasts water-efficient appliances, dual flush toilets and environmentally friendly windows made locally by RAM Industries Inc.
On the southern side of the home, which faces the backyard, an overhang protects an expansive storefront window from summer sun, yet still allows winter sun to make its way in.
"Summer sun is high, and winter sun is low in Houston," Reardon explained.
From the backyard, the 14 solar panels on the roof are clearly visible. About 15 percent of the home's power comes from these panels. Two of the panels are connected to a solar water-heating system that is used in conjunction with tankless Rinaii water heaters, which eliminate the need to heat water when it is not in demand.
The Ronns also have a sealed attic, which is only a few degrees warmer than the rest of the house. This means they don't have to worry about hot air leaking into their conditioned living area. It also means that the machinery housed in the attic — the entire heating and cooling system — doesn't have to work so hard.
All of this adds up to an electric bill that averaged $220 a month for the first year. Another pleasant surprise is how soundproof the Ronn house has proved to be.
"We live near Silber, and we used to hear every car," David Ronn said. "Now, in my bedroom, I hear absolutely nothing. We barely heard the hurricane. I had to get up and walk to the front door to see what was going on outside."