With Old Main at his back, Mark Novak gestures westward, toward the University of Arizona’s historic district. He’s talking about the many microclimates on campus — some large, some small, some hidden, others exposed.
Novak, a landscape architect in the UA’s Department of Planning, Design and Construction, knows all about microclimates, areas that differ climatically from their larger, surrounding climate. And he knows how important microclimates can be to flora, fauna and humans, especially on a desert campus such as the UA’s.
"Good urban design creates positive microclimates through a combination of building placement and building design and a combination of open space in between those buildings, which is the community space on campus or in a city," Novak says. "We want to create comfortable places that people can be outside doing healthy activities and interacting socially.
"If we just had a lot of buildings with a lot of mass that create heat, we would get an 'urban heat island' effect. If we can mitigate that with the proper amount of landscape, which helps cool things down, then we have a healthy, sustainable microclimate environment."
Developing a healthy, sustainable microclimate also means considering water use.
"We want trees and landscape that can thrive in xeric conditions, and that’s why we have more water-conserving and xeric landscape in the newer areas of campus than the types of plantings that we have in the historic district, which are higher water users," Novak says.
Currently, the UA’s historic district is the largest microclimate on campus, thanks to plentiful grass and a higher density of trees found there than on other areas on campus, Novak says.
"They help to transpire moisture, and that has a cooling effect," he says. "If you come by here on a summer evening when the air is very hot and dry, you can feel a difference of a couple of degrees while walking through this landscape."
Although big microclimates are apparent, microclimates also can be relatively compact. For example, Tucson is a microclimate in the Sonoran Desert, but microclimates can span one side of a building or even a courtyard, such as the one contained in the new ENR2 building.
ENR2’s large, shaded courtyard has lots of plants that transpire, and the building's exhaust air, which is the cooled air from its interior, is exhausted into the courtyard, which further cools it.
"It’s a combination of a natural and mechanical influenced microclimate," Novak says.
According to Novak, the campus has two major types of microclimates: "There’s the landscape microclimate, where the landscape cools the surrounding air, and the other involves large brick and concrete buildings that produce a warmer microclimate and allows trees to grow here that might not grow in other areas of Tucson or the surrounding desert."
In fact, a variety of subtropical trees has been planted on the south side of the main library.
"They’ve been placed close to the building to get the benefit of the heating effect of the building mass," Novak says. "We have a lot of unique trees from Mexico and Central America that you won’t find anywhere else."
To learn more about the campus and its flora, visit the UA’s campus arboretum.