From an energy efficiency perspective, roof technology has not progressed substantially in hundreds of years, but that is changing with the use of active thermal mass components, reflective pigments and coatings, subventing, radiant barriers and other novel techniques being tested by a team led by Bill Miller and Jan Kosny of ORNL's Building Envelopes group. Their prototype roof and attic system works by reducing attic temperatures by about 22 degrees Fahrenheit during a typical summer afternoon and decreasing the amount of heat that gets transferred through the attic floor to the living space.
At the heart of new roof system is a proprietary inorganic phase change material sandwiched between two reflective surfaces made of aluminum foil. This material is installed as a dynamic thermal barrier between the roof and attic area, creating separate air channels between roof rafters. The configuration is compatible with traditional wood and steel framing technologies. Moreover, the new phase change material overcomes problems that have plagued phase change materials for the past 40 years.
"In the 1970s and 1980s the housing industry made several moderately successful attempts to use phase change materials," Kosny said. "While these materials enhanced building energy performance, they were in many cases chemically unstable, were subject to corrosion or other durability problems and suffered from loss of phase change capability."
Another shortcoming of some previous phase change materials was their susceptibility to fire. Fire is not a problem with the ORNL material, according to Kosny, who noted that ORNL researchers are working with leading manufacturers of phase change material on the development of non-flammable organic material.
In tests at ORNL, phase change materials perform like conventional materials by absorbing heat as the temperature increases. However, as the material melts it continues to absorb large amounts of heat without a significant increase in temperature. Then, as night falls and the ambient temperature around the liquid phase change material decreases, it solidifies again and releases the stored heat to the night sky, Miller said.
With an outside temperature of 92 degrees Fahrenheit, tests at ORNL's Buildings Technology Center show temperatures of conventional attics at 127 degrees Fahrenheit vs. attic temperatures of 105 degrees with the Dynamic Attic Heat Exhaust System. Kosny and Miller filed a patent last year for this technology.
"The next generation roof will consist of infrared reflective materials that are dark in color yet reflect light as if they were white," Miller said. "In addition, radiant barriers and phase change materials will be integrated into a dynamic attic system that reduces utility bills for homeowners. The conservation strategies contribute on a much grander scale by lowering peak demand on utilities, reducing carbon emissions and, ultimately, they could lead to cleaner air."
If just half of the homeowners in the U.S. made sure they had R30 attic floor insulation and used this roof and attic system, the nation could reduce its Btu (British Thermal Unit) demand by about 100 trillion Btu.
This research is funded by the DOE Office of Energy Efficiency and Renewable Energy's Building Technologies program. UT-Battelle manages Oak Ridge National Laboratory for the Department of Energy.
Ron Walli | EurekAlert!
New, forward-looking report outlines research path to sustainable cities
24.01.2018 | National Science Foundation
Magnetic liquids improve energy efficiency of buildings
16.01.2018 | Friedrich-Schiller-Universität Jena
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
22.02.2018 | Life Sciences
22.02.2018 | Physics and Astronomy
22.02.2018 | Earth Sciences