News
ISPE Faculty Spotlight
Nader Chalfoun: Shaping outdoor spaces
November 30, 2007
By Stephanie Doster
Nader Chalfoun
As an architect, Nader Chalfoun is naturally interested in buildings. But it’s the spaces around and between them that intrigue him.
Some outdoor spaces seem more like an after-thought: concrete corridors that offer little more than a passage between buildings. Others show signs of more aesthetical planning, with landscaping, seating, and perhaps even a fountain or two. Almost all of them contribute to the urban heat island effect, and that’s what really grabs Chalfoun’s attention.
While many architects have tended to concentrate on a building’s footprint, outdoor spaces often are neglected, or even “abused,” said Chalfoun, an architecture professor at The University of Arizona who specializes in energy conservation, passive solar architecture, outdoor environmental comfort, green building materials, and sustainable architecture.
“Buildings affect the health of the atmosphere of our planet. They consume energy and emit carbon dioxide in the same manner that a car does on an annual basis,” Chalfoun said. “With spaces, people build parking lots. They put down asphalt. That encourages runoff water and there are no storm water management systems. Those spaces are the major cause of the urban heat island effect. They also become a dump for exhaust heat from all the air conditioning systems.”
The urban heat island effect describes urban and suburban temperatures that are 2 to 10 degrees Fahrenheit warmer than surrounding rural areas, according to the U.S. Environmental Protection Agency. Increased temperatures can increase peak energy demand, air conditioning costs, and air pollution levels, and can cause heat-related health problems. The lack of evapotranspiration and the use of certain materials like concrete, asphalt, and glass have contributed to increasing local warming.
“The man-made environment of urban development in large cities has altered the natural biological order of heat balance,” Chalfoun said.
With scientists predicting warmer average temperatures in the coming decades, Chalfoun set out to find what could be done in the field of architecture to simultaneously make people more comfortable outdoors, decrease the energy needed for cooling indoor spaces, and help mitigate the heat island effect.
He realized that the factors that contribute to energy consumption in buildings—radiant heat, moisture, evaporation, evapotranspiration, and air movement, to name a few—are similar to those that contribute to the urban heat island effect in outdoor spaces.
Using that knowledge and his twenty-five-plus years of experience working with indoor spaces, Chalfoun developed software called “Outdoors” to investigate or predict the thermal comfort conditions of an existing or future outside space, taking into account factors like air and radiant temperature, humidity, and air movement.
He has applied the software in his work as an architect and as a professor. As a consultant, he has used “Outdoors” in projects for cities like Scottsdale and Tucson, Arizona, and for Saudi Arabia, where he worked with fellow ISPE faculty member Martin Yoklic, an associate research scientist with the UA’s Environmental Research Lab. Chalfoun also has applied the software for theme parks in the emirate of Dubai and in Disneyland to figure out ways to help people chill out while waiting in the sun for a ride.
When he slips into professor mode, Chalfoun teaches his students how to use a laser gun, weather stations, and other sophisticated tools to take a variety of measurements, including a slew of temperature readings and wind speed and direction. Using the measurements, “Outdoors” software, scale models, and fish-eye lens photography, the students can predict how much heat is emitted and radiated in an outdoor space.
“Then we can start looking at how to modify the environment. Do we need to add shading devices, for example? Should they be opaque, semi-transparent, or porous? What should they be made of?” Chalfoun said.
Using shading strategies, landscape, fountains and water walls, cool towers—downdraft evaporative cooling devices—and alternative low-emittance ground cover materials, such as the paving system Grasscrete, the students can begin to modify moisture content and the mean radiant temperature outdoors.
“They find themselves doing some wonderful things with the space that benefits users, pedestrians, the buildings around the space, and efforts to reduce the urban heat island effect,” said Chalfoun, a one-time senior research associate in the Environmental Research Laboratory, a leader in environmental research and education in arid regions.
Chalfoun also is the director of the House Energy Doctor (HED) program, an education, research, and community service program that offers students hands-on inquiry-based learning about energy conservation and passive solar design while helping home and business owners lower their utility bills.
Each semester, students learn the fundamentals of solar geometry and physics, building thermodynamics, thermal comfort, climate and microclimate, energy conservation, and passive solar design. The students, er, house doctors, then analyze selected houses or buildings using site survey methods, advanced instruments, state-of-the-art simulation techniques, and interviews with the home or business owners. From that, they determine which design elements of the house or building contribute the most to energy waste and offer energy-saving solutions.
To Chalfoun, using energy efficiently and slashing the urban heat island effect should become a way of life and not just an alternative to business as usual.
“Sustainability is not an option anymore. It’s not something we can choose or not choose,” Chalfoun said. “We cannot afford to live without implementing sustainability into our lives.”