CSI works with Carnegie Mellon Students on Solar Home for National Contest

Problem: When Carnegie Mellon students undertook a competition to design a solar-powered house from scratch, they needed delivery and installation of appropriate heating, air conditioning and energy recovery systems. And they needed it fast. Even more important, the systems had to be highly efficient, scaled to the project and installed correctly. There were no conventional solutions for this novel residential application.

Solution: The professor overseeing the project recommended Variable Refrigeration Flow (VRF) technology. VRF technology is typically specified in commercial applications, but CSI was happy to help the students configure the system for their unique residential requirements and worked with them to ensure that it was installed correctly and on time to meet their tight deadline.

CSI worked with an interdisciplinary team of Carnegie Mellon students as they designed and constructed a solar-powered house that competed in the first Solar Decathlon, Sept. 27 - Oct. 4, 2007 on the National Mall in Washington, D.C.

Carnegie Mellon's team was one of 14 from universities around the country competing in the event. Solar Decathlon participants attempt to depend completely on the renewable energy collected from the sun to power their structures. During daytime hours, the solar-powered houses will store energy from the sun in batteries for use at night.
CSI assisted the students in selecting, customizing and installing green, energy efficient heating and cooling units based on Variable Refrigeration Flow (VRF) technology from City Multi. CSI also provided a New Air energy recovery unit.

It was the second such project for CSI, according to David Heckler, vice president. “VRF technology is right on the edge of broad acceptance,” he said. “Doing projects like this opens up a whole new realm of residential potential. The systems are highly efficient and fit very well into the concept of sustainable building.

“Unlike most conventional heating and cooling units, VRF systems cool or heat exactly as much as you need,” he continues. “And they provide extremely close temperature control. They can hold temperature within one degree.”

Architecture Professor Steve Lee of Carnegie Mellon concurs.  “From a sustainability point of view we wanted to demonstrate environmentally friendly heating and cooling,” explains. “City Multi uses VRF technology with a variable speed compressor. That means you can buy a unit sized for the largest the house could be and then plug in individual room units as you add to the house. It also relies on environmentally friendly refrigerants rather than Freon®.

“The Decathalon house features a separate kitchen, bedroom, etc., so we installed four evaporator units that are individually controllable. If you’re having dinner in the living/dining room you can have other rooms turned off to save energy. The variable component means that when you call something to come on, you only expend the energy for that one room. You’re not turning on a big air conditioner to cool one room,” Lee notes.

The Solar Decathlon is sponsored by the United States Department of Energy (DOE) to educate consumers about solar energy and energy-efficient products that are or will be available in the future. By involving student teams, the DOE also hopes to "provide stimulus to the next generation of researchers, architects, engineers and builders as they prepare to begin their careers.

Each house must also collect enough solar power to operate an electrically powered Ford Th!nk which the students used to get around town. The golf cart type transportation device is now being by the university's Facilities Management Services as an environmentally friendly maintenance vehicle.
"The dedication and commitment of the students to this project, has made this a rewarding experience for all of the faculty involved," Professor Lee notes.

Dave Heckler concludes, “As a company, we are always looking toward the future and the Solar Decathalon has given us an opportunity to participate in developing sustainable building technology that will become increasingly important to tomorrow’s homeowners. We also enjoy working with the students because they always have fresh new ideas and are open to new technologies.”