Tulsa duplex goes ultra green with four units on one lot
Architect Shelby Navarro’s home in Tulsa, Okla., has lots of eco-friendly features such as a grass roof, but the greenest one may be its siting. He lives in a duplex, each side with two units, on a small lot in a walkable neighborhood.
What makes this so special is that his duplex has quadrupled the 7,000 square-foot lot’s housing capacity. Previously, the land held only one small house, which Navarro had moved — in its entirety — to a different area.
This concept of density and walkability is crucial, and too often overlooked, in green development. I’ve added a rentable in-law suite to the efficient home I’m building in a Washington, D.C., suburb that’s filled with restaurants and shops.
Navarro and his wife, Rachel, live in one side of the duplex, which he designed, and sold the other. Each side has a comfortable 1,860 square feet with two bedrooms and two-and-a-half bathrooms, plus a 450 square-foot studio apartment over the detached garage.
“We continue to downsize as we learn and grow,” says Navarro, 40, who runs the Tulsa-based One Architecture firm. “We also realize the value in not having to mow the lawn.” His living roof and front yard have drought-tolerant buffalo grass, which doesn’t need to be cut.
Navarro’s duplex project — chosen as “This Week’s Green House” — won the top or platinum rating from the private U.S. Green Building Council’s LEED (Leadership in Energy and Environmental Design) program when it was completed in June 2008.
Since then, he says his monthly utility bills have never exceeded $100, due to the duplex’ ultra-efficient exterior and its geothermal heating and cooling system. The exterior walls are made of prefabricated SIPS or structural insulated panels, which are sheets of plywood around high-density foam. They create an airtight envelope. (I’m using them on my home, too.)
Also mitigating the home’s energy use are its grass roof, high-performance windows, Energy Star appliances and efficient lighting.
Navarro used green interior finishes as well: reclaimed Wisconsin barn wood; formaldehyde-free bamboo flooring; Sherwin-Williams no-VOC Harmony paint, recycled glass tiles, recycled-content bedroom carpet and Squak Mountain Stone kitchen countertops (made of recycled paper and recycled glass.) He estimates the project cost about $210 a square foot.
He’s no stranger to green living. He was raised by his grandparents on an organic farm in Verdigris, Okla., in a house with solar panels.
“I had a pet goat,” he recalls.
What he loves about his city home is its proximity to restaurants, coffee shops, art galleries and other amenities. He also enjoys its natural light.
“You don’t have to turn on the lights during the day,” he said. In a story about their duplex in Natural Home magazine, his wife Rachel also said how much she likes its windows.
“We have two long windows in the master bedroom, and they are my absolute favorite thing about the house,” she said in the story. “It was so unexpected how I would really enjoy them. I lay and watch the clouds go by. We have some bats that live in the neighborhood, and at dusk they kind of flutter around the window. It’s better than TV.”