Leon Glicksman: Less Is More
As the demand for energy escalates worldwide, MIT scientists are working on nuclear fusion, cheap solar panels, and more-efficient biofuel-producing microbes. But Leon Glicksman approaches the energy problem from a different perspective.
“People are always talking about how we can generate more energy,” says Glicksman, a professor of mechanical engineering and head of the architecture department’s building technology program. “But what about how we can use less?” Glicksman studies the physics of energy-efficient building design, then builds design tools to help architects incorporate energy-efficient features, such as natural air ventilation systems, into their buildings.
More-efficient ventilation could make a tremendous difference in the United States, where, Glicksman says, buildings consume 40 percent more energy than transportation (which gets so much attention as gas prices rise). He adds that residential and commercial buildings use 39 percent of the country’s total energy and about two-thirds of its electricity. “In commercial buildings, the majority of that energy is used for heating, cooling, and lighting,” says Glicksman, who notes that most windows in high-rises cannot be opened.
The idea behind natural ventilation is simple: rather than sealing up a building and controlling its internal temperature with a system of ducts, fans, and air chillers, architects and engineers could create systems that facilitate the natural flow of outside air using as little energy as possible. Glicksman says the air inside buildings is generally warmer than outside air. In an unsealed building, this temperature gradient creates a “chimney effect”: the denser, cooler air flows in, causing the warmer air to rise. “In some instances, you can add fans to assist the ventilation,” Glicksman says. “You’re using the entire building as a duct; the fan power is fairly nominal.” Design considerations, including a building’s overall shape and the placement of its windows, can also facilitate airflow. Glicksman’s studies have shown not only that naturally ventilated buildings save energy, but that people who live and work in them report a higher level of comfort.
Understanding the nuances of airflow requires “detailed numerical modeling using fluid dynamics,” says Glicksman. But “many architects don’t have a strong engineering background, and a lot of this stuff is Greek to them.” So he is working with a student to create software that will help architects design natural ventilation systems.
Glicksman has also built an online tool to encourage architects to plan sustainable buildings–buildings that use much less energy or rely more on renewable resources than on energy from polluting power plants. Architects can go to designadvisor.mit.edu and enter a future building’s location, use, and orientation and other specifications. The program, which has weather data for 30 cities around the world, then tells the designer the energy requirements for heating, cooling, and lighting the building. Using different sets of specifications, an architect can create four different scenarios for a building and use the advisor to compare their energy efficiency.
Some building owners and architects assume that energy-efficient design costs more. It doesn’t, says Glicksman, if energy efficiency is a goal from the start. He points to energy-efficient windows, which eliminate the need to install additional heat sources under windows to keep offices warm in winter. The windows cost more initially but ultimately save money because building owners don’t have to pay for the additional heating systems–or for the energy to run them.
Glicksman is intent on helping architects avoid energy-sapping design: “We want to give designers tools to make sure they don’t repeat these mistakes in new buildings.”