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U-M Researchers Look To Smart Building Exteriors To Reduce Energy Costs

Within the “envelopes” of commercial and residential buildings rests the promise of major, new energy efficiencies in the built-environment, according to University of Michigan researchers.

With $535,000 in seed funding provided by the Office of the Vice President for Research, the College of Engineering (CoE), the A. Alfred Taubman College of Architecture and Urban Planning, and the Rackham Graduate School, a team of U-M architects, civil engineers, as well as materials and environmental scientists will embark this fall on a two-year collaborative project they call, Integrated Responsive Building Envelopes (IRBE). Together they will explore the potential of intelligent building exteriors, or envelopes, that are capable of monitoring weather, daylight and occupant use to manage heating, cooling and lighting in dynamic ways that protect the environment and promote energy efficiency.

“We’re exploring the interface between a building’s external environment and the shelter it provides, and exploring the adaptation of that interface to better control the flow of energy,” said Jerome Lynch, a principal investigator (PI) on the project and a CoE associate professor of civil and environmental engineering and electrical engineering. “We are working to mitigate the total energy consumption of buildings and their environmental impact, while enhancing their comfort and aesthetic appeal.”

Building energy and environmental footprints are huge, said Lynch, noting that in urban centers like New York City, they account for 75 percent of greenhouse gas emissions. Nationwide, buildings account for an estimated 72 percent of the electricity consumed each year.

While greener, more efficient buildings have typically been associated with roof-top photovoltaic panels or wind turbines, the IRBE vision focuses on advanced building materials with embedded sensing and control devices that respond to shifting exterior conditions and occupants’ preferences. These include windows that automatically balance the availability of natural light with artificial light to meet occupant needs and walls that can store, heat/cool and transmit a comfortable supply of air as temperatures fluctuate throughout the day.

“We’re looking to provide hybrid building systems that are intelligent and responsive, by taking advantage of multi-functional materials that change their performance characteristics in response to various climatic conditions,” said Geoffrey Thün, also a PI on the project and an associate professor of architecture at the Taubman College. “The goal here is to make building envelopes with the dexterity to be more energy efficient and provide more user satisfaction while responding to seasonal and diurnal variations.”

To illustrate, Thün offers the following day-in-the-life of a commercial building equipped with a responsive envelope: It’s 5 a.m. in January and the building is empty, dark and relying on its advanced envelope to maximize its insulation capacity. Between 8 and 9 a.m., its occupants arrive. Sensors within the envelope measure external lighting and temperatures to respond to individual occupants’ comfort preferences, delivering heating through distributed systems while efficiently managing the load placed on the electrical grid. By midday, the sun has warmed the building’s exterior. Fresh air has been stored and pre-heated in the envelope cavity and is being distributed as needed. As the sun begins to set, artificial lighting is minimized to match occupancy and insulation values in the envelope rise as the evening chill sets in.

The IRBE team will examine a range of materials and assemblies that can be utilized for the envelope. These could include transparent and opaque materials, glazing and pressurized film systems as well as new types of green, ductile concrete. The team will also explore the creation, placement and use of sensing and actuation devices within these envelope systems to enable them to instantly respond to shifting conditions inside and out.

The researchers plan to create discreet responsive components, including sensors that will be tested in their labs to examine their inter-relationships as an aggregate system.

“A significant goal of the project is to conduct physical prototyping to not only validate our work, but to assess the plethora of operational logistics that would arise when developing such dynamic structures.” Thün said.

The IRBE team sees the OVPR grant as an opportunity to develop their concepts to the point where the can pursue additional external funding to refine their concepts. The timing, said Lynch, couldn’t be better.

“This project’s scope is very bold and has the potential to break a lot of old paradigms,” he said. “People have talked about these ideas as if they are 20 years away from becoming reality. We think the time is now and that’s what this project aims to prove.”