In the last decade, aluminum roofing panels have become increasingly popular as a replacement for asphalt, but it is not clear how much of this is due to improvements in the way roofs are manufactured and how much is a consequence of the introduction of more energy-dense materials.
Now, an international team of researchers has created an inexpensive, environmentally-friendly aluminum roof material that uses only a small amount of energy.
The result, reported this week in ACS’ Journal of Applied Physics, could improve efficiency of roof systems in urban areas.
The researchers developed a new way of manufacturing aluminum roof tiles, called a poly-aluminum composite, which they call a “smart” material, because it contains no chemical additives.
The process is so simple, the researchers say, that the material can be easily integrated into existing roofs without any modifications.
“This material is more environmentally friendly than asphalt, it’s also much less expensive, and it’s easy to integrate into existing structures,” said study lead author Shuzhen Zhang, a mechanical engineer at the University of California, Berkeley.
The team’s research is based on the same process that was used to produce the original poly-algae composite roof, which was shown to have superior efficiency.
“The main goal was to make a lightweight, highly efficient, low-cost, and highly recyclable aluminum roof for urban areas,” said Zhang, who was a member of the research team at UC Berkeley.
A smart roof design A key question in the research is whether the material will work well in a typical roof, with or without a window.
“We’re interested in whether this material will produce a good roofing system without any windows,” said lead author Eric D. Duan, a materials scientist at the National Renewable Energy Laboratory.
“And if so, it could help reduce energy consumption and pollution in urban environments.”
A typical roof can use up to 90 percent of the roof’s available energy, and the new roof will be able to provide up to 50 percent of its energy needs with only a few hours of work, Duan said.
“With this new approach, we can reduce the energy consumption of the entire roof without having to replace the entire system,” he said.
The first phase of the project was designed to test the material’s ability to produce high-quality roofs without windows.
“It’s the first time we’ve used a material to make roofs with a roof without windows,” Zhang said.
To produce the poly-metal composite, the team used two different types of aluminum foil: two types of a carbon nanotube layer sandwiched between two layers of silicon oxide, a material that is used in the roofing industry for roofing.
The layers were mixed and heated in a furnace to create a high quality metal oxide.
The metal oxide was then treated with a high heat and pressure process to make the composite.
To create the roof, the roof was poured into a mold and the material was heated to 600 degrees Celsius (2,200 degrees Fahrenheit).
A window was then added, which reduced the amount of time needed to create the composite material.
A final step was to coat the roof with the composite, but this took about 20 minutes, according to Zhang.
“That’s a lot of work to do in less than 15 minutes,” Zhang noted.
The composite material can produce a roof that is nearly 10 times lighter than asphalt.
The new material uses only 30 percent of aluminum’s energy and is environmentally friendly.
“A smart roof is an interesting topic because it can potentially benefit from all these new materials and also improve the efficiency of the existing roof,” said Duan.
“When we combine these materials with new technologies like photovoltaics, we’ll be able produce roof systems that are more efficient than asphalt roofs.”
Researchers say they have already found that the new material produces better results than asphalt roofing in certain situations.
“In some instances, it can improve performance by up to 20 percent compared to asphalt,” Duan explained.
The most recent study involved a three-year experiment.
The final product of this effort is expected to be available by 2021.
The research was funded by the Department of Energy’s Office of Science, the National Science Foundation, the NASA Goddard Space Flight Center, and an ERC Advanced Research Projects Agency (ARPA) grant.
A previous version of this story incorrectly described the work by Zhang as “high-tech” or “energy-efficient.”