Finding peak energy efficiency in small buildings is relatively easy. But to achieve zero net energy in bigger structures, a bit of creativity and ingenuity is in order.

That’s what the Architecture at Zero competition sought to bring out last year when it introduced its third annual challenge, asking designers to envision new mixed-use projects of up to 14 stories high situated in San Francisco's Tenderloin neighborhood. The competition—for designs of buildings that produce at least as much energy as it uses over a year—was sponsored by Pacific Gas and Electric Company and the American Institute of Architects, in collaboration with the Tenderloin Neighborhood Development Corporation.

The team behind Tetris Block, which received a special recognition award, took a down-to-earth approach, using cost-effective strategies employing current technologies. They avoided façade-integrated photovoltaics and in-slab radiant heating and cooling—which can be cost prohibitive— at the risk of not reaching an exact net zero design, for instance.

Set on an L-shaped block, the building includes five multi-function solar towers which prompts the flow of fresh air throughout the units and common areas thanks to its stacking effect, the team says. The glass towers not only serve as "solar chimneys," and break up the mass of the building, but also encourage circulation, and feature an open staircase for residents.

Education was a key part of this design, though, centering around occupant responsibility. The building is fit to instruct residents on the optimal times to close roller shades, insulated panels, and windows with the use of light signals.

The Chicago-based team behind the design included Duane B. Carter, Mike Stopka, Simon Mance, Scott Farbman, and Courtney Brower