A computer rendering of the planned UniSource Energy headquarters in downtown Tucson shows the frontage along Broadway, with Scott Avenue on the right. Excavation will begin this summer, with completion set for the end of 2011. COURTESY OF UNISOURCE ENERGY CORP.

The notion of using solar panels on the walls and installing electrical vehicle charging stations in the garage of its new headquarters downtown wasn't really optional for UniSource Energy Corp., said Paul Bonavia, the utility company's president and CEO.

UniSource, the parent company of Tucson Electric Power, urges its customers to go green, Bonavia said. "We cajole them and persuade them every way we can. This is a chance for us to lead by example."

Bonavia unveiled plans for his company's new headquarters at a news conference Thursday in the corporation's current offices in the UniSource Tower at 1 S. Church Ave.

Its new home, two blocks southeast on Broadway, will be a nine-story building with parking for 600 vehicles and 170,000 square feet of office space for at least 425 of TEP's 1,100 Tucson employees. Cost is estimated at $60 million.

Plans include meeting space and 8,700 square feet of retail space on the ground floor of the building's Broadway front.

The building will occupy two-thirds of the two-acre lot between Scott and Sixth avenues that formerly held the Santa Rita Hotel, which was razed last year.

The remainder of the lot, on the south side, will be reserved for "future development," Bonavia said. Ideas discussed include more retail space, condos or even a boutique hotel.

Any future project would be built by someone else, Bonavia said. "We're not a residential developer," he said, "but there is space there."

Retail uses would be geared to the needs of the people working in the building, as well as the neighborhood, Bonavia said. He mentioned a coffee shop, a dry cleaner and a credit union as possibilities.

The building itself will be energy-efficient and will include renewable-energy sources in its design. UniSource will seek LEED (Leadership in Energy and Environmental Design) certification from the U.S. Green Building Council.

The building's orientation minimizes exposure to the rising and setting sun on the east and west sides, said Michael Edwards of DAVIS, the Phoenix Design company that is teaming with Tucson architects Swaim Associates on the building's design.

Not all of the building materials have been selected, Edwards said, but the building will make use of thermally efficient glass and horizontal louvers for shade.

Solar panels are planned for the south side and a portion of the west side of the building, but the type and extent of those photovoltaic installations are still being decided.

Chuck Carefoot of the Ryan Companies said excavation will begin this summer and the building will be completed by the end of 2011. Construction will stay "within the fence line" of the site, Carefoot said, and not impede traffic on surrounding streets.

On StarNet: Go to this article at azstarnet.com to see a video with animated 3D views of the building design.

Contact reporter Tom Beal at 573-4158 or tbeal@azstarnet.com