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Posted: Nov 09, 2006

Risks in architectural applications of nanotechnology

(Nanowerk Spotlight) Building construction and operation is estimated to be a trillion dollar per year industry worldwide. And it is one that is ripe for the innovations offered by nanotechnology and nanomaterials. Already, dozens of building materials incorporate nanotechnology, from self-cleaning windows to flexible solar panels to wi-fi blocking paint. Many more are in development, including self-healing concrete, materials to block ultraviolet and infrared radiation, smog-eating coatings and light-emitting walls and ceilings. Nanotech is also starting to make the “smart home” a reality. Nanotech-enabled sensors are available today to monitor temperature, humidity, and airborne toxins. The nanosensor market is expected to reach $17.2 billion by 2012. Soon, inexpensive sensors will be available to monitor vibration, decay and other performance concerns in building components from structural members to appliances. Nanotechnology is also rapidly improving the batteries and wireless components used in these sensors. In the not-too-distant future, sensors will be ubiquitous in buildings, gathering data about the environment and building users. Building components will be intelligent and interactive. Nanosensors and nano building materials raise questions for building designers, builders, owners and users. What will the consequences be as buildings become increasingly intelligent and nanomaterials become an everyday part of the buildings that surround us?
Health and environmental risks
Buildings will undoubtedly be one of our prime areas of contact with nanoparticles both inhaled and absorbed through the skin. Already, building air filtration systems using nanoscale metallic catalysts and other nanotechnologies to remove airborne contaminants are available on the market. Nanoparticles from these filters could become airborne within the building. Research on the health effects of inhaled nanoparticles should be watched closely. Nanoparticles may also be released by building cleaning products and coatings.
Manufacturers of nanofilters, cleaning products and coatings suggest that nanotechnology makes these products more environ-mentally benign than other products. Ecology Coatings, for example, makes coatings that release non-volatile compounds like hydrogen as they cure – a clear improvement over coatings that release toxic volatile organic compounds into building air during curing. Other coatings, such as Nanoprotect for wood, metal and glass, and the nano-enhanced Behr paint available at Home Depot, claim to reduce mold and mildew.
Buildings will also be a prime source for absorption of nanoparticles through the skin. We already absorb nanoparticles through a wide range of products from sunscreen to cosmetics without apparent harmful effects. However, Canada’s ETC group and other NGOs have called for the recall of nano-enhanced sunscreens. Should their fears prove justified, and absorption of nanoparticles become a concern, surfaces such as countertops, handrails, door pulls and cabinets could be likely sources of absorption. Nanoparticles may also enter the body if building water supplies are filtered through commercially available nanofilters.
The release of nanoparticles into the environment may also be a concern. Airborne and waterborne particles from all of the sources described above may be introduced into the outdoors via building ventilation and wastewater systems. Cleansers may also enter the environment through building wastewater. While nanofilters offer the promise of cleansing the outgoing air and water from buildings, the environmental effects of nanoparticles should be monitored by the architectural community.
Societal risks
A completely different type of risk may emerge as sensors become more commonplace: A loss of privacy may result from users interacting with increasingly intelligent building components. Already wireless “push” technologies broadcast to users’ cell phones in proximity to products. And in Spain, Mexico and the U.S., building users implanted with subcutaneous ID chips are monitored within buildings. As monitoring and push technologies increase, how will users respond? What will be an acceptable level of participation in a “smart environment” – a network of intelligent, interacting sensors?
Related to privacy is the question of who controls the building environment and how they exercise that control. This could become an issue as building components become more attuned to user preferences and environmental conditions. For example, it will not be long before nanotech-enabled windows will be able to adjust their level of transparency automatically according to user prefer-ences, much like the individualized driver-side and passenger-side temperature settings available in some cars. If users can agree on settings this variability is a benefit, making the environment more comfortable according to each individual’s preference. But consider the likely future scenario in which interior partitions have variable transparency. Who controls the level of transparency? Are you guaranteed control over the degree of transparency in the walls of the rooms you occupy? How secure will you feel in your privacy know-ing that transparency, lighting or air quality can be controlled by others?
Dilemma facing early adopters
A final risk to consider as buildings begin to incorporate nanomaterials is faced by all adopters of this emerging technology. Will the “nano” label become a stigma if something goes wrong? Remember, developers at one time advertised the advantages of that miraculous new building material, asbestos. The flipside of this fear, however, and the one that seems more justified considering the overall performance of nanomaterials to date, is that valuable opportunities to improve building performance, user health and environmental quality may be missed if fears are exaggerated or information is lacking.
Regulatory agencies such as the International Conference of Building Officials and the American Society for Testing and Materials will have to confront the same quandaries facing the U.S. Food and Drug Administration and the Environmental Protection Agency to ensure proper testing and code definition for nanomaterials. Social issues such as privacy will require discussion and experimentation. As nanomaterials and sensors are woven into our buildings, accurate, up-to-date information will be essential in evaluating their risks.
By George Elvin, Copyright Nanowerk LLC
Dr. Elvin is an Associate Professor in the College of Architecture and Planning at Ball State University, a fellow of the Center for Energy Research, Education and Service, and a Senior Research Associate at the Building Futures Institute.

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