A Heat-Sensitive Material to Lower Energy Bills

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Project Title: Installation Design of Phase Change Material in Residential Homes

Team 17066 Members:
Nofal Alkhunaizi, engineering management
Nic Balda, mechanical engineering
Tyler Farley, industrial engineering
Alex Gill, mechanical engineering
Tanya Turner, mechanical engineering
Lorelei Wong, industrial engineering

Sponsor: Salt River Project

Keeping Casas Cool

Most Tucsonans are familiar with the spike in their electricity bill that comes with the summer months. They’re also familiar with the fact that this comes mostly from running air conditioning units during the day.

Phase change material, or PCM, could change that. PCM is a material that can store and release large quantities of energy by melting and resolidifying. Its heat-absorbing properties are already used to keep some industrial buildings cool during the summer.

In a project sponsored by the Salt River Project, Team 17066 is examining a way to install PCM into existing residential homes.

Saving Money Through Off-Hours Energy Use

The team is investigating a material that changes phase at 77 degrees Fahrenheit, which means that when the outdoor temperature exceeds 77 degrees, heat energy is channeled into melting the PCM, thus slowing the transfer of heat energy into the building. On the other hand, when temperatures dip below 77 degrees in the evening, the cooler air has to resolidify the PCM before the air can cool the inside of the house. Even if this means running the air conditioner in the evenings, it has the benefit of shifting energy use out of peak demand hours, when — thanks to the law of supply and demand — electricity is more expensive for both utility companies and customers.

“If the Salt River Project could flatten the peaks out, it would be less costly to them and obviously less costly to the customer,” said Steve Larimore, the team’s college mentor.

The students said one of the trickiest parts of their project is devising a system for retrofitting existing buildings, rather than designing new buildings or even taking measures like tearing down walls. But the challenging nature of the project has led to some creative methods of getting PCM into a house. For example, installing it in an attic — similar to the way it’s used in industrial buildings — is ideal, but not every home has an attic.

Drawing the Curtains on Excess Heat

Much of the heat that enters a house comes in through the windows, so the team is experimenting with PCM-filled curtains to block the heat. They’ve also investigated incorporating PCM into large pieces of furniture, such as beds or dressers; using customizable, decorative boxes that hang 4 to 6 inches below the ceilings; and even hiding the PCM behind large pieces of canvas artwork.

The team has started off by building a model house, a 3-by-3-foot box that they’ll try retrofitting with PCM in different configurations. Then they’ll shine a heat lamp on the box to simulate summer weather conditions and hook up an AC unit. If they find a setup that works well, they’ll pursue the results further by running similar tests on a software model. Hopefully, the students say, they’ll be a part of a project that affects homeowners everywhere for the better. In the meantime, they’re learning from and enjoying the process.

“There’s a lot of excitement leading up to the senior design project, because it has such real-world application and teams get to work with a real budget, but it lives up to the hype,” said team member Nic Balda. “I can definitely see why it’s one of the top-rated design programs in the nation.”

See this project and other designs that could change the way we live at the College of Engineering’s 2018 Design Day on April 30.