Project Sage Special Report: A Crowning Achievement in Green

This building waters its own desert oasis. It soon will sport a green roof of desert plants, and a wind tunnel that occupants will use to improve building energy audits.
Sept. 30, 2009
(Click to enlarge)Yellow orchid vine, native to Sinaloa and Sonora, climbs the south side of the CALA East building. The curtain of vine is designed to filter sunlight and screen the building, suppressing heat buildup.
(Click to enlarge)Yellow orchid vine, native to Sinaloa and Sonora, climbs the south side of the CALA East building. The curtain of vine is designed to filter sunlight and screen the building, suppressing heat buildup.
(Click to enlarge) Water recycled from building condensate and rain runoff from the 9,500-square-foot roof of the CALA East building is fed back into a pond and the surrounding landscape. The landscape design also controls urban flooding and slows storom-water runoff.
(Click to enlarge) Water recycled from building condensate and rain runoff from the 9,500-square-foot roof of the CALA East building is fed back into a pond and the surrounding landscape. The landscape design also controls urban flooding and slows storom-water runoff.

When the College of Architecture and Landscape Architecture dedicated a 34,000-square-foot expansion of its building, it also added a living laboratory.

The three-story building, known as CALA East, doesn’t merely have landscaping; it has a desert laboratory representing five biomes -- ecological communities -- of the Sonoran desert. The wetlands biome is represented by an 18,000-gallon pond and lush riparian vegetation.  Such a tall order for water in the desert has come with a built-in solution: a system that collects the building’s condensate and rainwater from its roof.

The harvested water is deposited in a cistern about the size of an average school bus -- 7 feet in diameter, 38 feet tall. It can hold 11,600 gallons of water. A subtext of the landscape design, said Ronald Stoltz, director of the School of Landscape Architecture and Planning, was to “live off the waste of the building.” The water-harvesting system -- bolstered by blow-off from an adjacent university well and graywater from drinking fountains -- comes close. These sources provide 83 percent of the irrigation necessary for the establishment of the two-year-old Underwood Family Sonoran Landscape Laboratory, a one-acre oasis of native plants and mesquite trees.

The crowning touch for CALA East will be a green roof of desert plants – succulents and cactus. Green roofs -- layers of grasses or plants in a thin soil over a water-tight membrane -- provide a living buffer of insulation, saving energy and cutting costs associated with heating and cooling. The roofs also provide attractive habitat for birds and inviting outdoor spaces for people.

Stoltz said they are experimenting to find the right types of plants, soil composition and irrigation regimes."We do have roof gardens in Arizona, but they water them every hours, and we can't have that," he said. Because of this, the roof will be "desert green."

When all is in place, the roof will become every bit the living laboratory as the landscape garden on the ground. They will monitor soil and subsoil temperatures. They will also track the temperature of the membrane that goes between the roof and the plant layer as well as the temperature beneath the roof to study the thermal transfer.

In addition, they will add a 10 kilowatt array of photovoltaic panels -- donated by Tucson Electric Power -- and a weather station.

On the ground floor of CALA East, one of the college’s older programs is also being transformed.

The House Energy Doctor program, headed by architecture professor Nader Chalfoun, has been conducting sophisticated, instrument-based energy audits for residents and businesses of Tucson, Phoenix and Flagstaff since 1986. Students in the program study energy efficiency and sustainability concepts and research building materials. Chalfoun is adding a wind tunnel that can simulate 40-mile-an-hour gales to the lab.

Students are trained to go into the community to do energy audits and identify the weak points in the performance of buildings. Residents request an audit and fill out a form explaining the nature of their concerns – leaky windows, no shade on the outside – and describing their heating and cooling system. “And then off we go,” said Chalfoun.

The energy “doctors” give their clients “a prescription.”

They’re about to expand the program to the point where the diagnosis leads to help with the solution. Chalfoun said the new element of House Energy Doctor, backed by a U.S. Department of Energy grant, will stimulate the economy and provide jobs by partnering with professional builders to implement the recommendations and the research.