New Efforts for Energy Efficiency in Buildings
Article originally from American Chemistry magazine
Styrofoam Structural Insulated
Sheathing (SIS) is a residential
wall system that combines
structural and water-resistant
properties with insulation.
The American Chemistry Council (ACC) comprises many pioneers making important contributions to research and development (R&D). Some of these developments focus on energy issues, including reducing costs and providing future sustainability. The following are some recent building-related projects where ACC member companies have reached new milestones in energy efficiency.
Styrofoam sheathing
Styrofoam™ extruded polystyrene (XPS) foam, patented by Dow in 1944, is a lightweight, durable material with thermal and moisture-resistant properties. More than 60 years later, it continues to be used throughout the world and is easily recognized by its trademark blue color. Installed for insulative properties from rooftops to basement walls in millions of residential and commercial buildings, Styrofoam is estimated to reduce energy costs by more than $10 billion annually.
This year, Dow introduced Styrofoam Structural Insulated Sheathing (SIS™), a residential wall system that combines structural and water-resistant properties with insulation. The sheathing is made of up to 80 percent post-consumer content (by weight) and is estimated to reduce the average homeowner’s energy bills by approximately $200 to $500 each year.
Roof assemblies
Currently, three to four percent of all waste in U.S. landfills comes from old roofs. While traditional roofs are typically replaced every seven to 10 years, installed protected membrane roof (PMR) designs can last for more than 40 years, reducing the frequency of landfill waste.
Unlike a traditional roof system, a PMR system using Styrofoam insulation shields and protects a roof’s waterproofing membrane because the insulation is placed on top of the membrane, protecting it from common causes of failure, including sunlight, severe weather, and extreme hot and cold temperatures. Insulation helps the roof membrane maintain a steady temperature, minimizing the harmful effects of freeze-thaw cycles, weathering, and physical damage during and after construction. The insulation resists water, so it can be reused if the roof is ever replaced, further minimizing landfill waste.
PMR assemblies also stay cooler than darker membrane-surfaced roofs, reducing the overall temperature of a building and helping keep the immediate surrounding area cool.
Polymer sheets
When it comes to energy-efficient buildings, a number of materials and technologies being developed are resulting in a new wave of architectural designs. One example at the 2008 Summer Olympics in China was the Beijing National Stadium, also known as the Bird’s Nest.
The Bird’s Nest resembles loosely woven twigs, but owes its architectural qualities to a synthetic material: ethylene tetrafluoroethylene (ETFE), a fluorocarbon-based polymer. ‘Pillows’ made from ETFE film fill the spaces between and above the ‘twigs’ of the Bird’s Nest.
The formula for ETFE was originally developed in the 1970s by DuPont for use as an aeronautic insulation material. Made from a waste product of lead and tin mining, the resin in its raw state bears a resemblance to sugar. After ETFE is heated and extruded into a paper-thin film, it can be welded into large sheets that can be used as building skin or can be woven together into cushions pumped with air.
ETFE sheets are transparent, like glass, but are only one percent of the weight of glass, transmit more light, and cost 24 to 70 percent less to install. The sheets are resistant to ultraviolet (UV) rays, and the film is nonstick and therefore better able to keep clean.
In addition, ETFE is recyclable. Once it has reached the end of its useful life, thought to be at least 50 but possibly up to 200 years, it can be melted down and reused.
When the sheets are fused into pillows and pumped with air, the material takes on both stability and high insulation properties, resulting in a variety of design possibilities. For example, Daly Genik Architects and Bruce Mau used patterned ETFE film on skylights for the underground Art Center College of Design in Pasadena, Calif., in 2004.
Another project in the works with ETFE is a whale-shaped aquarium on New York City’s Coney Island. Design specifications for the aquarium include red light-emitting diodes (LEDs) woven through the ETFE fabric, while the steel frame supporting it will be fashioned to look like a roller coaster.
On the other side of the Atlantic, a personal residence in the suburbs of Barcelona, Spain, is being designed to bring the benefits of ETFE home.
The Villa Nurbs will include a patented system for the roof that will filter light, monitor energy use, and open or close as needed, allowing homeowners to open the roof whenever they wish to gaze at the stars.
With files from Dow Chemical and DuPont.