A 31,600-square-foot mixed-use structure, Step Up on 5th includes 46 studio apartments of affordable housing and support services for the homeless and mentally disabled. Each unit is less than 250 square feet. The structure also includes ground-level commercial space and an art gallery and studio for a nonprofit arts program.

The building was sited to control solar cooling loads and shaped with prevailing winds and buoyancy required for natural ventilation in mind. Windows are placed to maximize daylight, and south-facing windows are shaded to control heat gain. The building has no air conditioning outside of the ground-floor commercial space, two offices, and two manager’s offices. To condition the space and address temperature swings between day and night, concrete floors and walls were strategically placed to be used as thermal heat sinks. During the day, perforated metal screens form canopies that shade the building, and operable windows allow for cross-ventilation. According to the architects, ultrahigh efficient hydronic heating, and sustainable building materials contribute to building performance 50 percent better than conventional buildings of its type. The building is designed to accommodate solar panels in the future and project analyses project that a 30kW system, part of the original design, would create a net-zero-energy building.

The structure’s stormwater retention system retains 100 percent of the stormwater on site. It is collected in a subsurface infiltration system and then is returned to the groundwater after being cleaned. Inside each unit, an emphasis was placed on indoor air quality. Formaldehyde-free MDF cabinetry, low-VOC paints, natural linoleum, and fluorescent lighting with low mercury content were specified.

By the numbers:

Building gross floor area: 31,600 square feet
Number of occupants: 46 (plus 65 visitors)
Percent of the building that is daylight: 99
Percent of the building that can be ventilated or cooled with operable windows: 96
Total water used, indoors and outdoors: 650,150 gallons per year
Calculated annual potable water use: 20.6 gallons per square foot per year
Total energy (MBtu per yr): 846.7 (simulation case)
EPA performance rating: 75
Percent total energy savings: 48
LEED rating: Not submitted

For more information on each project, including extended slideshows, click on the individual projects in the sidebar at left. To access a database of past Top Ten projects, visit aiatopten.org. ECO-STRUCTURE will be covering the 2011 COTE Top Ten projects in depth in its July/August issue.