IN THE DESERT SOUTHWEST—a region beginning to feel the effects of climate change more acutely than many others—weather extremes may include less frequent but more intense rainfall, as well as flash floods, hard freezes, extreme heat, high winds, and long droughts. ENR2, a new five-story, 150,954-square-foot research, administration, and instruction building on the University of Arizona campus in Tucson, responds to these risks, thus creating an ecofriendly environment that saves energy and water and evokes the canyons and mesas of the Sonoran Desert. Resilience efforts are already paying off.
Designed by GLHN Architects and Engineers in Tucson and Richärd+Bauer architects in Phoenix and built by Hensel Phelps Construction Company, the $75 million building integrates innovative solutions to architecture for a desert environment, with many sustainable components that minimize the use of energy and water while protecting the structure from the effects of extreme weather. Slated for LEED Platinum certification, the building’s key resiliency features are its passive energy systems, building orientation, and courtyard design. Completed in July 2015, ENR2 was designed to further interdisciplinary research in earth and environmental sciences, natural resources, and math and related sciences. The building includes faculty offices, conference space, research and work space, and instructional dry laboratories. A 600-seat auditorium and a coffee café meet the needs of a growing student population.
The building serves as a living model of evolving ideas about environmental sustainability and resilience—especially appropriate considering that the lead tenant is the Institute of the Environment, which conducts research on effective adaptation and mitigation factors related to climate change. “We also house the university’s environmental groups, so this building had to be the most environmentally responsible building on campus,” says May Carr, senior architect in the university’s planning, design, and construction department and project manager for the building.
Resilience measures for the building included fortifying the exterior to address high winds, sun and monsoon rain exposure, and summer temperatures that can reach more than 110 degrees Fahrenheit. Many of the important features of the building are passive systems and design strategies that require little if any assistance from renewable energy sources. These passive strategies include configuring the building around a central courtyard that integrates exterior circulation and interaction space and reduces the interior’s need for air conditioning by about 30 percent.
The building minimizes the impacts of summer heat with the building mass, which is constructed of poured-in-place concrete, and has shading and strategically reduced openings. Vertical metal fins and overhangs shade the building on the south facade. In the courtyard, garden terraces and balconies form overhangs that create comfortable shaded microclimates for year-round outdoor meetings and socializing. These building features also evoke a desert slot canyon atmosphere with curvilinear lines, light, and shadows. “The way we are protecting the building is through shading,” says Carr. “Our harshest exposures are on the east and west sides, and those have limited openings with a lot of building mass.”
The building was designed to perform well and consistently at a comfortable temperature of 74 degrees Fahrenheit to save on energy costs and provide resilience, given the likelihood of increasing hot spells. The dedicated outdoor air system combined with overhead induction coils known as “active” chilled beams provide the primary heating, ventilation, and air conditioning for perimeter office spaces on floors two through five. The interior open-office spaces rely on an underfloor low-velocity air displacement system, which costs less to install and operate. On the courtyard balconies and terraces, large fans help circulate cooler air, and plants temper the building through evapotranspiration. Heat gain and energy costs on the building have been greatly reduced, compared to other campus buildings.
“We are looking to see how the building responds to higher heat and longer heat events, and how increasing drought conditions are going to affect how the building works,” says Carr. “If the grid goes down and it’s 110 degrees outside, opening all the doors will not help cool the interior significantly.” Although so far, she says, even when it is very hot, “the courtyard space has been doing what we wanted it to do.”
Drought-prone areas like Tucson also face the risk of flooding, as less frequent but more intense rainfall runs off sun-hardened ground. Although the university does not build in the floodplain, the risks of storm-related flooding and power outages still exist. ENR2 resilience strategies included elevating the mechanical equipment above the 100-year-flood plain and providing backup power and on-site generators to allow the building to continue to be used even during a power outage.
The building also addresses drought risks with water harvesting and green infrastructure featuring native and drought-tolerant plants. When it rains, the water free-falls to the courtyard, drips through balcony and terrace planters, and flows into catch basins before being collected in the 52,000-gallon holding and filtration tank installed underground. Landscaped beds are irrigated with the stored stormwater runoff, captured building condensate, and reclaimed water. “There is always recognition of the presence of water, but it is being done in a way that acknowledges our desert environment,” notes Carr.
“We are looking to maximize the longevity and efficiency of our buildings,” says Pete Dourlein, associate vice president for the university’s planning, design, and construction department. “As an institution, our goal is to build 50- to 100-year-life buildings.”
Even with the latest energy-systems technology and high-quality materials, the cost of building ENR2 was comparable to other university buildings, he says. Separating the building with a central courtyard cost more than constructing a solid block building because of more exterior surface area, but the advantages included reducing heat, solar gain, and the amount of interior space that needed to be cooled. Greater exposure to natural light and views also has been proven to boost people’s productivity.
“ The way we are protecting the building is through shading.” —May Carr
Energy-efficient features such as chilled beams and underfloor electrical distribution systems cost an estimated 2 percent more than conventional construction features to install. Projections show the building’s energy-saving features alone will save 30 percent on energy costs compared to conventional buildings.
Early responses indicate the building is boosting the university’s and departments’ images, a benefit in recruiting staff members and students. “Some of the faculty and researchers are already talking it up with their colleagues across the country and creating a buzz about this phenomenal new environment they are going to work and collaborate in,” says Dourlein. “Our assets are our people. That is what the space is for, even if we may not be able to put a price to that.”