Transmaterial

Extremely noisy environments near airports, roads, or loud entertainment centers pose acoustic challenges for building occupants, and typical windows cannot provide adequate protection against certain types of noise pollution. A double or triple layer of glass will absorb the high frequencies, but can do nothing against low-frequency noise such as that produced by aircraft or the bass tones of loud music.

Researchers at the Fraunhofer Institute for Structural Durability and System Reliability LBF and Darmstadt University of Technology have recently developed a new type of soundproof window. "Tests have shown that our windows are capable of lowering noise levels by an average of six decibels at frequencies between 50 and 1000 hertz. The perceived noise indoors is only half as loud," says Dr. Thilo Bein, who manages the institute’s department of energy, environment and health. "We have even been able to reduce the volume of certain test signals by up to 15 decibels." The experts have predicted a reduction of up to 10 dB for the engine noise of passenger aircraft in the frequency range below 1000 Hz.

When noise waves meet the walls of a building, they can be propagated to the interior by various routes. One is by causing the windows to vibrate, thus carrying the noise into the building. The other is by transmitting sound waves to the interior via the bridges in the structure where the curtain-wall elements are attached to the frame of the building. In both cases, the researchers have found a way to prevent the propagation of sound energy. Acceleration sensors attached to the window panes measure the vibrations generated by the noise. A thin chip of piezoelectric material also attached to the window counteracts the vibration by generating an oscillation at the same pitch but in the opposite sense to that measured by the sensor – causing the pane to move in the opposing direction. "We have devised a similar solution for the points where the outer cladding is attached to the frame of the building. In this case, a stack of piezoelectric chips, rather than a single piezoelectric strip, counteracts the impinging force," says Bein.

The researchers presented a prototype of the new soundproof window at the Hannover Fair in April. According to Bein’s estimations, the new active noise-reducing windows could be on the market in about four years’ time. [via the Fraunhofer Institute; suggested by James Thornburg, Columbus.]

Now that energy consciousness is becoming increasingly widespread, one cannot fail to notice common practices that call for more energy-efficient solutions. One of these practices involves refrigeration within cold climates: a process that involves cooling goods within a heated space, which is highly impractical considering the amount of time that 'free cooling' exists outside.

The Freeaire Refrigeration System is designed to provide such free cooling for walk-in coolers, freezers and cold storage warehouses. The system utilizes an electronic controller to finely tune the operation of standard refrigeration equipment, and this controller simply monitors the outdoor temperature and desired temperature settings and stops refrigerator evaporator fans when not needed, which also reduces the compressor's refrigeration load. Proper airflow is maintained when the evaporator fans switch off by operating one or more energy-efficient circulating fans.

Roughly half the electricity consumed by a typical convenience store is used for refrigeration. The Freeaire System is designed to save energy year-round by allowing refrigeration equipment for a walk-in cooler or freezer to run only as much as it has to. Once the system is installed, evaporator fans typically operate 50 to 75% less often, and reach-in door heaters operate 90% less frequently. Condensing units also usually experience a 10 to 20% reduction in operations. Moreover, a Freeaire System saving 20,000 kilowatt-hours annually can prevent 40,000 pounds of CO2 from being emitted to the atmosphere. [via R. H. Travers; suggested by James Thornburg, Columbus, OH.]

In the United States there are 46,837 miles of highways with miles of sound barrier walls being erected daily to mitigate the negative impacts of highway systems on urban neighborhoods. At the same time, these transportation systems alone produce 1.4 billion tons of airborne pollution annually. With the increasing prominence of this additional component to our highway infrastructure, the public is beginning to demand a more appealing design solution to highway-generated air, sound, and light pollution.

In addition to mitigating sound and light pollution as present highway barrier systems do, the Superabsorber system also absorbs airborne pollutants. Designed by Douglas Hecker and Martha Skinner of Clemson-based FieldOffice, this innovative system has the potential to significantly reduce airborne pollution in urban areas with the application of photocatalytic cement products that have been demonstrated to reduce air pollution in urban areas by 50% when covering just 15% of urban surfaces. The inclusion of this surface application on future concrete barrier systems represents a significant amount of surface area for absorption of air pollution in urban areas. [via Field Office.]