Nanotechnology
for
Green Building
Green Technology Forum 2007
Nanotechnology for Green
Building
© 2007 Dr. George Elvin
Green Technology Forum
Table of Contents
Executive Summary
Part 1: Nanotechnology and Green Building
1. Introduction
1.1 Green Building
1.2 Nanot...
6. Solar energy
6.1 Silicon solar enhancement
6.2 Thin-film solar nanotechnologies
6.3 Emerging solar nanotechnologies
7. ...
cover: flexible solar panel from konarka
acknowledgements: an initial study of energy-efficient nanomaterials was made pos...
Nanotechnology for Green Building © 2007 Dr. George Elvin
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Executive summary
This report offers a comprehensive research ...
Nanotechnology for Green Building © 2007 Dr. George Elvin
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dramatic improvements are possible in this area, although thei...
Nanotechnology for Green Building © 2007 Dr. George Elvin
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Part 1. Nanotechnology and Green Building
1. Introduction
The ...
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estimated $60 billion in healthcare costs annually. Deforestat...
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In 2007, the green building sector of the $142 billion U.S. co...
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1.2 Nanotechnology
Nanotechnology, the understanding and contr...
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as we explore biological systems which are configured to the n...
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1.3 Convergence
“It is not as though nanotechnology will be an...
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Rank Technology
1 Electricity Storage
1 Engine Efficiency
2 Hy...
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exception. The demands of public and private building owners ...
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Part 2. Materials
2. Insulation
The market for green building...
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Improvement
CO2 Reduction (tons/yr) by
2010
Thermal
Insulatio...
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Nanoscale materials hold great promise as insulators because ...
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Currently, major companies in the aerogel arena include the C...
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Aerogels offer superior insulation
Aerogels offer 2-3 times t...
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2.2 Thin-film insulation
Insulating nanocoatings can also be ...
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Exterior reflectivity can also be controlled by nanofilms. Te...
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generation to tap into,” said CEO Stuart Burchill. The compan...
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Inside an insulating nanocoating
Nansulate Shield is an insul...
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2.4 Emerging insulation technologies
Work is underway at many...
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stock. And unlike cellulose fiber, fiberglass batts, and rigi...
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Self-cleaning facade systems utilizing the latter technology ...
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Pilkington Activ gradually breaks down and loosens dirt, allo...
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Natural Genetics (THONG) at the Eddie Bauer flagship store in...
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not diminish when exposed to the harsh elements. “LuxShield c...
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Depolluting nanocoatings show considerable promise in cleansi...
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A current drawback to self-cleaning photocatalytic coatings u...
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Diamon-Fusion International (DFI) offers a patented scratch-r...
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TEG in Stuttgart, Germany have developed a nanotechnology tha...
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End of the line for subway-riding germs
"Public transportatio...
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Plumbing aint what it used to be
Microban International offer...
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3.7 UV protection
Ultraviolet (UV) light can break down many ...
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functionality of colored coatings. NanoZ is used, among other...
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Bonderite NT is said to be suitable for surface pretreatment ...
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environments. During the lifetime of the coating, they say, m...
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Hycrete also coats reinforcing steel surface with a monomolec...
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Transfer Center at the University of Southern California’s Vi...
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Self-assembling nanoscale chains form nano-super-
glue
Resear...
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Biomimicry: learning from the lotus leaf
Through nanoscience ...
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Adhesion without adhesives
Scientists have developed material...
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heating/cooling 44%
lighting + other
appliances 33%
water hea...
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Light-emitting diodes: always low prices!
Wal–Mart expects to...
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BridgeLux InGaN (indium gallium nitride) power-LED chips repl...
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lighting include “Method for fabricating substrate with nano ...
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photons. OLEDs are highly efficient, long-lived natural light...
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top emission OLEDs. Their flexible organic light-emitting dio...
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be applied to LEDs, molded into fluorescent components and li...
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"This will completely change the way we use
lighting"
Carbon ...
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NANOTECHNOLOGY FOR GREEN BUILDING 2007
Published on: Mar 3, 2016
Published in: Government & Nonprofit      
Source: www.slideshare.net


Transcripts - Nano green building

  • 1. Nanotechnology for Green Building Green Technology Forum 2007
  • 2. Nanotechnology for Green Building © 2007 Dr. George Elvin Green Technology Forum
  • 3. Table of Contents Executive Summary Part 1: Nanotechnology and Green Building 1. Introduction 1.1 Green Building 1.2 Nanotechnology 1.3 Convergence Part 2: Materials 2. Insulation 2.1 Aerogel 2.2 Thin-film insulation 2.3 Insulating coatings 2.4 Emerging insulation technologies 2.5 Future market for nano-insulation 3. Coatings 3.1 Self-cleaning coatings 3.2 Anti-stain coatings 3.3 Depolluting surfaces 3.4 Scratch-resistant coatings 3.5 Anti-fogging and anti-icing coatings 3.6 Antimicrobial coatings 3.7 UV protection 3.8 Anti-corrosion coatings 3.9 Moisture resistance 4. Adhesives 5. Lighting 5.1 Light-emitting diodes (LEDs) 5.2 Organic light-emitting diodes (OLEDs) 5.3 Quantum dot lighting 5.4 Future market for lighting
  • 4. 6. Solar energy 6.1 Silicon solar enhancement 6.2 Thin-film solar nanotechnologies 6.3 Emerging solar nanotechnologies 7. Energy storage 8. Air purification 9. Water purification 10. Structural materials 10.1 Concrete 10.2 Steel 10.3 Wood 10.4 New structural materials 11. Non-structural materials 11.1 Glass 11.2 Plastics and polymers 11.3 Drywall 11.4 Roofing Part 3: Conclusions 12. Additional benefits 12.1 Nanosensors and smart environments 12.2 Multifunctional properties 12.3 Reduced processing energy 12.4 Adaptability to existing buildings 13. Market forces 13.1 Forces accelerating adoption 13.2 Obstacles to adoption 14. Future trends and needs 14.1 Independent testing 14.2 Life cycle analysis 14.3 Societal concerns 14.4 Environmental and human health concerns 14.5 Regulation References and links
  • 5. cover: flexible solar panel from konarka acknowledgements: an initial study of energy-efficient nanomaterials was made possible by a fellowship at the center for energy research, education and service
  • 6. Nanotechnology for Green Building © 2007 Dr. George Elvin 1 Executive summary This report offers a comprehensive research review of current and near future applications of nanotechnology for green building. Its results suggest that the potential for energy conservation and reduced waste, toxicity, non-renewable resource consumption, and carbon emissions through the architectural applications of nanotechnology is significant. These environmental performance improvements will be led by current improvements in insulation, coatings, air and water purification, followed by forthcoming advances in solar and lighting technology, and more distant (>10 years) potential in structural components and adhesives. U.S. demand for nano- enhanced building materials totaled less than $20 million in 2006, but the market is expected to reach almost $400 million by 2016. Green building, meanwhile, accounts for $12 billion of the $142 billion U.S. construction market.1 The convergence of green building and nanotechnology will result in economic opportunities for both industries and, most importantly, significant improvements in human and environmental health. Based on our research, we divide the timeline for nano-enhanced building materials into three phases. First, current architectural market applications of nanotechnology are led by nanocoatings for insulating, self-cleaning, UV protection, corrosion resistance, and waterproofing. Many of these coatings incorporate titanium dioxide nanoparticles to make surfaces not only self-cleaning but also depolluting, able to remove pollutants from the surrounding atmosphere. Insulating nanocoatings promise significant energy savings, particularly for existing buildings which can be difficult to insulate with conventional materials. Already gaining market share rapidly in industrial applications, insulating nanocoatings will soon have a major impact in architecture. Coming soon are nanotechnologies for solar energy, lighting, and water and air filtration. Nano-enhanced solar cell technologies such as organic thin-film and roll-to- roll processing are also well under development and will gain an increasing share of the solar cell market in coming years. Not far behind is nano-enhanced lighting such as organic light-emitting diodes (OLEDs) and quantum dot lighting. Market applications of these technologies have already begun with small consumer devices like cellphone screens, are beginning to enter the architectural lighting market, and will gain an increasing percentage of that market in the future due to their energy- saving capabilities. Nanotechnologies for water and air filtration, already widely available as consumer products, will gain an increasing percentage of the market for built-in filtration systems. In the future, advances in fire protection through nanotechnology suggest great opportunity as extensive research in this area moves from the universities and research centers into commercial production. Extensive research underway on nano- enhancement of structural materials including steel, concrete and wood suggests that
  • 7. Nanotechnology for Green Building © 2007 Dr. George Elvin 2 dramatic improvements are possible in this area, although their marketplace applications are, in most cases, many years off. Public and building industry reaction to nanotechnology has been largely positive so far. Nanomaterials have already been used in hundreds of buildings, including high- end projects like the Jubilee Church in Rome by Richard Meier and Partners and New York’s Bond Street Apartment Building by Herzog & de Meuron. We have even incorporated several nanocoatings into our office construction at Green Technology Forum with positive results. However, a number of factors stand in the way of widespread adoption. Current obstacles to the adoption of nanotechnology for green building include the high cost of many nanotech products and processes, risk aversion and the traditional hesitancy of the building industry to embrace new technologies, as well as uncertainty about the health and environmental effects of nanoparticles and public acceptance of nanotechnology. Lack of independent testing and the current reliance on manufacturer claims in determining the architectural and environmental performance of most nano- products could also hinder adoption. But as this report reveals, many nano-enhanced products are available today which offer substantial architectural and environmental performance improvements over conventional products. Many coatings, for example, can protect building surfaces and reduce the need for harsh chemical cleansers while producing no volatile organic compounds (VOCs) and even removing pollutants from their surroundings. If consumers embrace nanotechnology as a green technology, if building owners, architects, contractors and engineers accept uncertainty and risk and embrace innovation, and if the high cost of nano-products continues to fall, the tremendous promise of nanotechnology for green building will be realized. As prices for nano-enhanced building products continue to fall, as buyers weigh their life cycle and environmental cost advantages, and building industry leaders become more familiar with nanotechnology, its widespread adoption seems inevitable. Nanotechnology for green building will reduce waste and toxicity, as well as energy and raw material consumption in the building industry, resulting in cleaner, healthier buildings. In addition to the human health and environmental benefits nanotechnology for green building is poised to make, economic benefits for both the building industry and nanomaterials industry appear considerable. The demand for green building is at a an all-time high, and building owners, architects, contractors and engineers adopting nanotechnology for green building are likely to emerge as leaders and be rewarded accordingly for their services. For nanotechnology companies, green building represents one of the largest markets possible for new products and processes. The Green Technology Forum report on nanotechnology for green building identifies 130 startups and established companies offering or developing nanomaterials for green building, 54 projects underway at universities and research centers, 43 recent patents available for licensing, and over 250 citations and links to these resources.
  • 8. Nanotechnology for Green Building © 2007 Dr. George Elvin 3 Part 1. Nanotechnology and Green Building 1. Introduction The design, construction and operation of buildings is a $1 trillion per year market as yet largely untouched by nanotechnology. Demand for nanomaterials in the U.S. construction industry in 2006 totaled less than $20 million.2 However, as this report shows, the migration of the entire building industry toward more sustainable “green” practices is a multi-billion dollar opportunity for the makers and suppliers of nanotech-based materials and products. For architects, engineers, developers, contractors and building owners, new nanomaterials and nano-products offer extraordinary environmental benefits to help meet the rapidly growing demand for greener, more sustainable buildings. Nanotechnology, the manipulation of matter at the molecular scale, is bringing new materials and new possibilities to industries as diverse as electronics, medicine, energy and aeronautics. Our ability to design new materials from the bottom up is impacting the building industry as well. New materials and products based on nanotechnology can be found in building insulation, coatings, and solar technologies. Work now underway in nanotech labs will soon result in new products for lighting, structures, and energy. In the building industry, nanotechnology has already brought to market self-cleaning windows, smog-eating concrete, and many other advances. But these advances and currently available products are minor compared to those incubating in the world’s nanotech labs today. There, work is underway on illuminating walls that change color with the flip of a switch, nanocomposites as thin as glass yet capable of supporting entire buildings, and photosynthetic surfaces making any building façade a source of free energy. By 2016, the market for nanomaterials in U.S. construction is expected to reach almost $400 million, twenty times its current volume.3 1.1 Green building The advent of the nano era in building could not have come at a better time, as the building industry moves aggressively toward sustainability. Green building is one of the most urgent environmental issues of our time. The energy services required by residential, commercial, and industrial buildings are responsible for approximately 43 percent of U.S. carbon dioxide emissions. Worldwide, buildings consume between 30 and 40 percent of the world’s electricity.4 Waste from building construction accounts for 40 percent of all landfill material in the U.S., and sick building syndrome costs an
  • 9. Nanotechnology for Green Building © 2007 Dr. George Elvin 4 estimated $60 billion in healthcare costs annually. Deforestation, soil erosion, environmental pollution, acidification, ozone depletion, fossil fuel depletion, global climate change, and human health risks are all attributable in some measure to building construction and operation. Clearly, buildings play a leading role in our current environmental predicament. Environmental impact of buildings Buildings figure prominently in world energy consumption, carbon emissions, and waste. (Source: Levin, “Systematic Evaluation and Assessment of Building Environmental Performance (SEABEP),” Buildings and Environment, Paris, June 9-12, 1997) But they also offer a vast opportunity to improve environmental quality and human health. Green building is a catch-all phrase encompassing efforts to reduce waste, toxicity, and energy and resource consumption in buildings. The green building movement has grown to the point that major cities like Chicago and Seattle now require new buildings to comply with strict environmental standards. More and more public and private owners are requiring that new construction meet stringent sustainability benchmarks like the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) criteria. The Council of American Building Officials' Model Energy Code (residential) and ASHRAE Standard 90.1 (commercial) propose tougher energy saving requirements, and the proposed EU Directive on the Energy Performance of Buildings also sets minimum energy performance standards for new buildings. atmospheric emissions 40% energy use 42% raw materials use 30% solid waste 25% water use 25% water effluents 20% 100%50%0% percentage of annual impact (us)
  • 10. Nanotechnology for Green Building © 2007 Dr. George Elvin 5 In 2007, the green building sector of the $142 billion U.S. construction market is expected to exceed $12 billion.5 And as owners, architects and builders worldwide become increasingly committed to green building, a true paradigm shift is emerging, from buildings as one of the primary causes of environmental damage and global climate change to the industry with the greatest potential to reduce carbon emissions, waste, and energy consumption. Analyses of global climate change and global-scale plans to alleviate it affirm the importance of building as our primary opportunity to heal the planet. “Tackling Climate Change in the U.S.,” by the American Solar Energy Society, for example, suggests that 40 percent of the energy savings required to achieve necessary carbon reductions could come from the building sector, with transportation and industry providing about 30 percent each.6 Better building envelope design, daylighting, more efficient artificial lighting, and better efficiency standards for building components and appliances are all opportunities to make the building industry the leader in fighting global climate change and advancing sustainable development and energy conservation. Green building practitioners seek to implement sustainable development, “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” in the design, construction and operation of buildings.7 They strive to minimize the use of non-renewable resources like coal, petroleum, natural gas and minerals, and minimize waste and pollutants. Energy conservation is critical to green building because it both conserves resources and reduces waste and pollutants. But a number of obstacles stand between green builders and these goals. Education and economics are certainly factors, and efforts are well underway to inform clients that initial design and construction costs for green buildings are typically less than 5 percent more than the waste- and energy-intensive buildings of the past, and that life cycle costs for green buildings are actually lower. Policies, regulations and standards also play a role, and these are changing quickly in some areas to allow for greener alternatives like recycled materials and graywater systems. But for the building industry to achieve its potential as the leader in sustainable development, new materials are urgently needed. A trip to the lumber yard just a few years ago to buy materials for a new deck, for example, would turn up the unpleasant options of arsenic-laden pressure-treated lumber, non-renewable old-growth redwood, or environmentally toxic vinyl decking. An effort to conserve energy by installing attic insulation would meet with the alternatives of fiberglass, polystyrene, or cellulose laced with fire-retardant chemicals, all considered dangerous. Current windows are extremely poor insulators, leading to increased energy consumption. And alternatives to polyvinyl chloride (PVC) pipe for plumbing are healthier than this known carcinogen but scarce and costly. Now, however, a new frontier is opening in building materials as nanotechnology introduces new products and new possibilities.
  • 11. Nanotechnology for Green Building © 2007 Dr. George Elvin 6 1.2 Nanotechnology Nanotechnology, the understanding and control of matter at dimensions of roughly one to one hundred billionths of a meter, is bringing dramatic changes to the materials and processes of science and industry worldwide. $13 billion worth of products incorporating nanotechnology were sold last year, with sales expected to top $1 trillion by 2015.8 In 2004, over $8 billion was spent in the U.S. alone on nanotech research and development. Dimensions at the nanoscale The diameter of a nanoparticle is to the diameter of a soccer ball as the soccer ball’s diameter is to the Earth’s. (Source: Green Technology Forum) By working at the molecular level, nanotechnology opens up new possibilities in material design. In the nanoscale world where quantum physics rules, objects can change color, shape, and phase much more easily than at the macroscale. Fundamental properties like strength, surface-to-mass ratio, conductivity, and elasticity can be designed in to create dramatically different materials. Nanoparticles have unique mechanical, electrical, optical and reactive properties distinct from larger particles. Their study (nanoscience) and manipulation (nanotechnology) also open up the convergence of synthetic and biological materials
  • 12. Nanotechnology for Green Building © 2007 Dr. George Elvin 7 as we explore biological systems which are configured to the nanoscale. Crossing the traditional boundaries between living and non-living systems allows for the design of new materials with the advantages of both, and it raises ethical concerns. Advances in biomaterials and biocomposites converge with advances in nanotechnology, and an increase in their application to construction seems certain to emerge in the future. Carbon nanotubes Carbon nanotubes can be up to 250 times stronger than steel and 10 times lighter, as well as electrically and thermally conductive. (Source: Nanomix) But with new materials and technologies come new concerns. Uncertainty surrounding the interaction of nanoscale particles with the environment and the human body has led to caution and concern about toxicology, worker health and safety, and regulation. Regulations specific to nanomaterials and products have been slow to emerge, partly due to the inherent difficulty in regulating materials based on particle size, as well as lack of public outcry in favor of stiffer regulation and the success so far of self- regulation by industry and the avoidance of any nano-disasters.
  • 13. Nanotechnology for Green Building © 2007 Dr. George Elvin 8 1.3 Convergence “It is not as though nanotechnology will be an option; it is going to be essential for coming up with sustainable technologies.” advises Paul Anastas, director of the American Chemical Society Green Chemistry Institute. 9 The nanotech community appears ready to meet Anatsas’ challenge, and the market for nano-based products and processes for sustainability is expected to grow from $12 billion in 2006 to $37 billion by 2015.10 New materials and processes brought about by nanotechnology, for example, offer tremendous potential for fighting global climate change. According to the report, “Nanotechnologies for Sustainable Energy,” by Research and Markets, “Current applications of nanotechnologies will result in a global annual saving of 8,000 tons of carbon dioxide in 2007, rising to over 1 million tons by 2014.”11 Globally, nanotechnologies are expected to reduce carbon emissions in three main areas: 1) transportation, 2) improved insulation in residential and commercial buildings, and 3) generation of renewable photovoltaic energy.12 It is worth noting that the last two of these three areas are centered in the building industry, suggesting that building could in fact lead the green nano revolution. Many nano-enhanced products and processes now on the market can help create more sustainable, energy-conserving buildings, providing materials that reduce waste and toxic outputs as well as dependence on non-renewable resources. Other products still in development offer even more promise for dramatically improving the environmental and energy performance of buildings. Nano-enabled advances for energy conservation in architecture include new materials like carbon nanotubes and insulating nanocoatings, as well as new processes including photocatalysis. Nanomaterials can improve the strength, durability, and versatility of structural and non-structural materials, reduce material toxicity, and improve building insulation. Nanotechnology markets 2007 Building construction is not yet a significant market for nanotechnology. (Source: Cientifica, “Nanotechnologies and energy whitepaper,” 2007) chemical 53% semiconductor 34% electronics 7% aero/defense 3% pharma/health 2% automotive 1% food <1%
  • 14. Nanotechnology for Green Building © 2007 Dr. George Elvin 9 Rank Technology 1 Electricity Storage 1 Engine Efficiency 2 Hydrogen Economy 3 Photovoltaics 3 Insulation 4 Thermovoltaics 4 Fuel Cells 4 Lighting 6 Lightweighting 6 Agriculture Pollution Reduction 7 Drinking Water Purification 8 Environmental Sensors 8 Remediation Ranking of environmentally friendly nanotechnologies Most environmentally friendly nanotechnologies are well-suited to use in buildings (Source: Oakdene Hollins, “Environmentally Beneficial Nanotechnologies,” 2007) The chart and table above reveal that building construction is not yet a significant market for nanotechnology. But that is not necessarily bad news for either the construction industry or the marketers of nano-products. The construction industry has long been slow to adopt new technologies, and the nanotech era is proving to be no
  • 15. Nanotechnology for Green Building © 2007 Dr. George Elvin 10 exception. The demands of public and private building owners for greener materials, demands increasingly being enforced as regulations in many instances, will soon force architects and engineers to specify greener materials in buildings. This demand, combined with the environmentally friendly character of most nano-products for architecture, will create a synergy that we expect will result in a boom in demand for nanotechnology for green building.
  • 16. Nanotechnology for Green Building © 2007 Dr. George Elvin 11 Part 2. Materials 2. Insulation The market for green building materials and technologies will of course be determined more by market pull--the needs of architects, owners and contractors--than by the technological push of new nanomaterials discovered and developed in the laboratory. But the convergence of green building demands and green nanotechnology capabilities over the next 5-10 years appears very strong. It suggests eight categories of nanotechnology for green building that are the focus of this report. Insulation Coatings Adhesives Solar energy Lighting Air and water filtration Structural materials Non-structural materials The demand from both public and private enterprise for more energy efficient buildings will lead to significant growth in the insulation sector in the next few years. Valued at $7.2 billion value in 2005, it is expected to reach $9.5 billion by 2010.13 Current building insulation is estimated to save about 12 quadrillion Btu annually or 42 percent of the energy that would be consumed without it.14 Building insulation reduces the amount of energy required to maintain a comfortable environment. Reduced energy consumption, in turn, means reduced carbon emissions from energy production. Insulation is, in fact, the most cost-effective means of reducing carbon emissions available today. Improving on current building insulation could save even more energy and carbon emissions. EU households, for instance, are responsible for one quarter of EU carbon emissions, roughly 70 percent of which comes from meeting space heating needs. Space heating savings through better insulation in Germany, The Netherlands, Italy, UK, Spain and Ireland, would reduce EU carbon emissions by 100 million metric tons per year.15 As the table below indicates, improved thermal insulation could meet over 25 percent of EU carbon reduction goals by 2010. In the U.S., improved insulation could save 2.2 quadrillion Btu of energy (3 percent of total energy use) and reduce carbon emissions by 294 billion pounds annually.16
  • 17. Nanotechnology for Green Building © 2007 Dr. George Elvin 12 Improvement CO2 Reduction (tons/yr) by 2010 Thermal Insulation 174-196 Glazing Standards 50 Lighting Efficiency 50 Controls 26 Potential sources of EU CO2 emission reductions Buildings have the potential to become leading sources of CO2 reductions. (Source: CALEB Management Services, "Assessment of the potential savings of CO2 emissions in European building stock", May 1998) Today’s building insulation industry is in many ways a model of large-scale industrial recycling. Fiberglass insulation manufacturers are the second largest user of post- consumer recycled glass in the U.S., slag wool insulation typically contains 75 percent recycled content, and most cellulose insulation is approximately 80 percent post- consumer recycled newspaper by weight.17 Health effects of several insulating materials are a concern, however, and improved health and environmental performance could lead to greater use and therefore energy conservation. Some sources argue that the fibers released from fiberglass insulation may be carcinogenic, and fiberglass insulation now requires cancer warning labels. There are also claims that the fire retardant chemicals or respirable particles in cellulose insulation may be hazardous. And the styrene used in polystyrene insulation (often known by the brand name Styrofoam) is identified by the EPA as a possible carcinogen, mutagen, chronic toxin, and environmental toxin.18, 19 Polystyrene also poses a resource concern because it is produced from ethylene, a natural gas component, and benzene, which is derived from petroleum. Two other insulating materials, polyisocyanurate and polyurethane, are also derived from petroleum. Nanotechnology promises to make insulation more efficient, less reliant on non- renewable resources, and less toxic, and it is delivering on many of those promises today. Manufacturers estimate that insulating materials derived from nanotechnology are roughly 30 percent more efficient than conventional materials.20
  • 18. Nanotechnology for Green Building © 2007 Dr. George Elvin 13 Nanoscale materials hold great promise as insulators because of their extremely high surface-to-volume ratio. This gives them the ability to trap still air within a material layer of minimal thickness (conventional insulating materials like fiberglass and polystyrene get their high insulating value less from the conductive properties of the materials themselves than from their ability to trap still air.) Insulating nanomaterials may be sandwiched between rigid panels, applied as thin films, or painted on as coatings. Making nanofibers from cotton waste While cellulose insulation is made from 80 percent post-consumer recycled newspaper, the equivalent of 25 million 480-pound cotton bales are discarded as scrap every year in the garment industry. "Producing a high-performance material from reclaimed cellulose material will increase motivation to recycle these materials at all phases of textile production and remove them from the waste stream," said Margaret Frey, an assistant professor of textiles and apparel at Cornell. Frey and her collaborators are using electrospinning techniques to produce usable nanofibers from waste cellulose. These nanofibers could form the basis of new insulating materials from cellulose which, as the basic building block of all plant life, represents the most abundant renewable resource on the planet.21 2.1 Aerogel Aerogel is an ultra-low density solid, a gel in which the liquid component has been replaced with gas. Nicknamed “frozen smoke”, aerogel has a content of just 5 percent solid and 95 percent air, and is said to be the lightest weight solid in the world. Despite its lightness, however, aerogel can support over 2,000 times its own weight. Because nanoporous aerogels can be sensitive to moisture, they are often marketed sandwiched between wall panels that repel moisture. Aerogel panels are available with up to 75 percent translucency, and their high air content means that a 9cm (3.5”) thick aerogel panel can offer an R-value of R-28, a value previously unheard of in a translucent panel.22 Architectural applications of aerogel include windows, skylights, and translucent wall panels.
  • 19. Nanotechnology for Green Building © 2007 Dr. George Elvin 14 Currently, major companies in the aerogel arena include the Cabot Corporation (makers of Nanogel,) Aspen Aerogels, Kalwall (using Cabot’s Nanogel,) and TAASI (makers of Prstina aerogels.) Brown University currently has several aerogel technologies available for licensing, including one that can be used as a coating to permit printing on materials that normally cannot be printed on. These aerogels can bind various gases for use as detectors, and can be colored or ground into very small particles and applied like ink using a printer. They are also transparent and have a low refractive index, making them useful as light-weight optical materials.23 Aerogel: the world’s lightest solid A 9cm (3.5”) thick aerogel panel can offer an R-value of R-28. (Source: Sandia National Laboratory)
  • 20. Nanotechnology for Green Building © 2007 Dr. George Elvin 15 Aerogels offer superior insulation Aerogels offer 2-3 times the insulating value of other common insulating materials. (Source: Aspen Aerogels) Nanogel panels provide translucency and insulation High-insulating Nanogel panels are available with up to 75 percent translucency. (Source: Kalwall) aspen aerogels spaceloft polyisocyanurate foam polystyrene foam mineral wool fiberglass batts r-value per inch 0 4 8 12 16 20 24
  • 21. Nanotechnology for Green Building © 2007 Dr. George Elvin 16 2.2 Thin-film insulation Insulating nanocoatings can also be applied as thin films to glass and fabrics. Masa Shade Curtains, for example, are fiber sheets coated with a nanoscale stainless steel film. Thanks to stainless steel's ability to absorb infrared rays, these curtains are able to block out sunlight, lower room temperatures in summer by 2-3º C more than conventional products, and reduce electrical expenses for air conditioning, according to manufacturer claims.24 Heat absorbing films can be applied to windows as well. Windows manufactured by Vanceva incorporate a nanofilm “interlayer” which, according to the company, offers cost effective control of heat and energy loads in building and solar performance superior to that of previously available laminating systems. By selectively reducing the transmittance of solar energy relative to visible light, they say, these solar performance interlayers result in savings in the capital cost of energy control equipment as well as operating costs of climate control equipment. Benefits include the ability to block solar heat and up to 99 percent of UV rays while allowing visible light to pass through.25 Stainless steel nanofilm improves UV light blockage Masa Shade Curtains reduce room temperatures and air conditioning by improving blockage of ultraviolet (UV) rays. (Source: Suzutora Corporation) 3M has developed a range of nanotech-based window films that reduce heat and ultraviolet light penetration. Their films reject up to 97 percent of the sun's infrared light and up to 99.9 percent of UV rays. Unlike many reflective films, theirs are metal- free and therefore less susceptible to corrosion in coastal environments and less likely to interfere with mobile phone reception. These films also have less interior reflectivity than the glass they cover. 26 masa shade curtain 84% untreated curtain 58% uv blockage 0% 100%
  • 22. Nanotechnology for Green Building © 2007 Dr. George Elvin 17 Exterior reflectivity can also be controlled by nanofilms. Technology from Rensselaer Polytechnic Institute and Crystal IS, Inc. has led to highly anti-reflective coatings utilizing silicon dioxide and titanium dioxide nanorods for a variety of surfaces. Their coating has a refelctivity index of just 1.05, the lowest ever reported.27 Infrared (IR) rays can also be blocked using transparent IR-absorbing coatings for heat-absorbing films for windows. VP AdNano ITO IR5, used in transparent film coatings, improves solar absorption properties while maintaining optical transparency, according to its manufacturer, Degussa. The use of AdNano ITO on windows, they claim, improves heat management, greatly reducing the energy consumption of air conditioners, thereby lowering greenhouse gas emissions. Production of AdNano ITO, they add, does not pollute the environment with heavy metals, and consumes very little energy because drying and calcination take place at moderate temperatures.28 2.3 Insulating coatings Insulation can also be painted or sprayed on in the form of a coating. This is a tremendous advantage nanocoatings offer over more conventional bulk insulators like fiberglass, cellulose, and polystyrene boards, which often require the removal of building envelope components for installation. Because they trap air at the molecular level, insulating nanocoatings even a few thousands of an inch thick can have a dramatic effect. Nanoseal is one company already making insulating paints for buildings. Their insulating coating is also being used on beer tanks by Corona in Mexico, resulting in a temperature differential of 36 degrees Fahrenheit after application of a coating just seven one thousands of an inch thick.29 Industrial Nanotechnology, the makers of Nansulate HomeProtect Interior paint, advertise that the average surface temperature difference when applied correctly is approximately 30 degrees Fahrenheit for three coats. For Nansulate HomeProtect ClearCoat, they claim an average surface temperature difference of approximately 60 degrees Fahrenheit. Nansulate PT is being applied to aluminum ceiling panels in the new Suvanabhumi International Airport in Bangkok, the world’s largest airport.30 HPC HiPerCoat and HiPerCaot Extreme are currently used as thermal barrier coatings by NASA and NASCAR. Their ceramic-aluminum coating process, they report, reduces radiant heat and ambient underhood temperature in autos by more than 40 percent. It also offers a corrosion-resistant alternative to environmentally harmful chrome-plating.31 Industrial Nanotech is even developing thermal insulation that will generate electricity. The thin sheets of insulation use the temperature differential that insulation creates as a source for generating electricity. “The fact that there is almost always, day or night and anywhere in the world, a difference between the temperature inside a building and outside a building gives us an almost constant source of energy
  • 23. Nanotechnology for Green Building © 2007 Dr. George Elvin 18 generation to tap into,” said CEO Stuart Burchill. The company is now designing the first prototype material and filing patents.32 NanoPore Thermal Insulation uses silica, titania and carbon in a 3D, highly branched network of particles 2-20 nanometers in diameter to create a unique pore structure. According to its maker, NanoPore Thermal Insulation can provide thermal performance unequalled by conventional insulation materials. In the form of a vacuum insulation panel, It can have thermal resistance values as high as R-40/inch--7 to 8 times greater than conventional foam insulation materials. NanoPore’s makers claim that its conductivity can actually be lower than air at the same pressure. Its superior insulation characteristics, they say, are due to the unique shape and small size of its large number of pores. Solid phase conduction is low due to the materials low density and high surface area, and NanoPore’s proprietary blend of infra-red opacifiers greatly reduces radiant heat transfer.33 Nanoparticles with extreme insulating value can also be incorporated into conventional paints, as in the case of INSULADD paints. As its manufacturer describes it, the complex blend of microscopic hollow ceramic spheres that makes up INSULADD have a vacuum inside like mini-thermos bottles. The ceramic materials have unique energy savings properties that reflect heat while dissipating it. The hollow ceramic microspheres in INSULADD create a thermal barrier by refracting, reflecting, and dissipating heat.34 Superior insulation with reduced thickness 330 cm3 of Nanopore insulating nanocoating (right) provides the same R- value as 7000 cm3 of polystyrene (left). (Source: Nanopore Incorporated) expanded polystyrene nanopore
  • 24. Nanotechnology for Green Building © 2007 Dr. George Elvin 19 Inside an insulating nanocoating Nansulate Shield is an insulation material designed specifically for the construction industry. It is an ultra-thin insulation that, according to its manufacturer, has an R-Value many times higher than the current best building insulation available. It is a nanocomposite insulation composed of 70 percent “Hydro-NM- Oxide” and 30 percent acrylic resin and performance additive. A liquid applied coating, the material dries to a thin layer and provides insulation as well as corrosion and rust protection. The manufacturers describe their product’s performance this way: “Thermal conduction through the solid portion is hindered by the tiny size of the connections between the particles making up the conduction path, and the solids that are present consist of very small particles linked in a three-dimensional network (with many "dead-ends"). Therefore, thermal transfer through the solid portion occurs through a very complicated maze and is not very effective. Air and gas in the material can inherently also transport thermal energy, but the gas molecules within the matrix experience what is known as the Knudsen effect and the exchange of energy is virtually eliminated. Conduction is limited because the "tunnels" are only the size of the mean-free path for molecular collisions, smaller than a wave of light, and molecules collide with the solid network as frequently as they collide with each other. The unique structure... nanometer-sized cells, pores, and particles, means poor thermal conduction. Radiative conduction is low due to small mass fractions and large surface areas.”35 Hydro-NM-Oxide ----------- 10 to 13 Polyurethane Foam -------- 6.64 Fiberglass (batts) ----------- 3.2 Cellulose ---------------------- 3.2 to 3.7 R-value comparison of insulation Similar to aerogel, insulating nanocoatings like the active ingredient in Nansulate Shield provide 2-3 times the R-value of ordinary insulators (Source: Industrial Nanotech)
  • 25. Nanotechnology for Green Building © 2007 Dr. George Elvin 20 2.4 Emerging insulation technologies Work is underway at many universities and research centers to develop new insulating materials based on nanotechnology. University of California scientists working at Los Alamos National Laboratory, for instance, have developed a process for modifying silica aerogels to create a silicon multilayer that enhances the current physical properties of aerogels. With the addition of a silicon monolayer, they say, an aerogel's strength can be increased four-fold. This could expand the range of applications for aerogels, which must currently be protected by surrounding panels.36 At EMPA Research Institute in Switzerland, work is underway to create vacuum insulated products using plastic films such as PET, polyethylene and polyurethane treated with an ultra-thin coating of aluminum. Only about 30 nanometers thick, the aluminum layer significantly reduces the gas permeability of the film while at the same time barely raising its thermal conductivity. The resulting cladding layer is thin, homogeneous and gas-tight. The higher cost (still about double that of conventional materials) is offset by the space-saving potential the new materials offer.37 Many products of current research on nano-insulation are available for licensing. For example, eight licensable patents for aerospace insulation materials are available through the Engineering Technology Transfer Center at the USC Viterbi School of Engineering, including “Composite Flexible Blanket Insulation,” “Durable Advanced Flexible Reusable Surface Insulation,” and “Flexible Ceramic-Metal Insulation Composite.” 38 Also available for licensing are NASA’s Ames Research Center’s novel nanoengineered heat sink materials enabling multi-zone, reconfigurable thermal control systems in spacesuits, habitats, and mobile systems. This platform technology can be adapted to a wide range of form factors thanks to a flexible metallic substrate. 2.5 Future market for nano-insulation If the field performance of nano-insulation products lives up to manufacturer claims, these products could foster dramatic improvements in energy savings and carbon reduction. However, independent testing of insulating nanomaterials and products in use will be necessary to verify manufacturer claims and convince potential buyers of their effectiveness. Some manufacturers are already making the results of such testing public, with encouraging results. One of the greatest potential energy-saving characteristics of nanocoatings and thin films is their applicability to existing surfaces for improved insulation. They can be applied directly to the surfaces of existing buildings, whereas the post-construction addition of conventional insulating materials like cellulose fiber, fiberglass batts, and rigid polystyrene boards typically require expensive and invasive access to wall cavities and remodeling. Nanocoatings could also make it much easier to insulate solid-walled buildings, which make up approximately one third of the UK’s housing
  • 26. Nanotechnology for Green Building © 2007 Dr. George Elvin 21 stock. And unlike cellulose fiber, fiberglass batts, and rigid polystyrene boards, nanocoatings can be made transparent. Their application to existing structures could lead to tremendous energy savings, and they do not appear to raise the environmental and health concerns attributed to fiberglass and polystyrene. 3. Coatings Insulating nanoparticles can be applied to substrates using chemical vapor deposition, dip, meniscus, spray, and plasma coating to create a layer bound to the base material. Other types of nanoparticle coatings can also be applied by these methods to achieve a wide variety of other performance characteristics, including: Self-cleaning Depolluting Scratch-resistant Anti-icing and anti-fogging Antimicrobial UV protection Corrosion-resistant Waterproofing Thanks to the versatility of many nanoparticles, surfaces treated with them often exhibit more than one of these properties. On this versatility and the environmental improvements possible through the use of nanocoatings, the European Parliament's Scientific Technology Options Assessment concluded: "At present, nanotechnologies and nanotechnological concepts deliver a variety of mostly incremental improvements of existing bulk materials, coatings or products. These improvements point in several directions and often are aimed at improving several properties at the same time. With respect to substitution this means that nanotechnological approaches often cannot lead to direct substitution of a hazardous substance, but may lead in general to a more environmentally friendly product or process."39 3.1 Self-cleaning coatings Self-cleaning surfaces have become a reality thanks to photocatalytic coatings containing titanium dioxide (TiO2) nanoparticles. These nanoparticles initiate photocatalysis, a process by which dirt is broken down by exposure to the sun’s ultraviolet rays and washed away by rain. Volatile organic compounds are oxidized into carbon dioxide and water. Today’s self-cleaning surfaces are made by applying a thin nanocoating film, painting a nanocoating on, or integrating nanoparticles into the surface layer of a substrate material.
  • 27. Nanotechnology for Green Building © 2007 Dr. George Elvin 22 Self-cleaning facade systems utilizing the latter technology can be found in the Jubilee Church in Rome by Richard Meier and Partners, the Marunouchi Building in downtown Tokyo, the General Hospital in Carmarthen, UK, and Herzog & de Meuron’s Bond Street Apartment Building in New York. Self-cleaning windows are now available from most major window manufacturers including Pilkington, PPG, Saint-Gobain, and Andersen. While the Marunouchi Building and General Hospital have self-cleaning windows, in the Jubilee Church titanium dioxide nanoparticles are actually integrated into the precast concrete facade panels. The panel system’s manufacturer, Italcementi Group, has even tested TiO2 on road surfaces and found it reduced nitrogen oxide levels by up to 60 percent. At present, their self-cleaning facade system costs 30 to 40 percent more than regular concrete, but they believe that self-cleaning materials will save money in the long run.40 The fiber cement company, Nichiha, employs nanotechnology in three precast panel lines for exterior cladding; Canyon Brick, Field Stone and Quarry Stone. Working together with paint manufacturers, Nichiha created a self-cleaning finish on its fiber cement panels that allows a microscopic layer of water to protect the finish from dirt or soot. A simple rain, they say, will wash away stains leaving the exterior looking new.41 Ai-Nano is, according to its manufacturer, a non-toxic, environmentally friendly, hygienic photocatalytic coating. It creates a semi-permanent invisible coating on most surfaces to provide anti-bacteria, anti-mold, anti-fungus, UV protection, deodorizing, air purification, self-cleaning and self sanitizing functionality.42 Self-cleaning nanocoatings can also be applied as paint, and a variety of commercially available paints take advantage of TiO2’s properties. Herbol by Akzo Nobel, based on BASF’s nanobinder COL.9, displays much lower dirt pick-up and excellent color retention, according to its manufacturer. They say that during the production of COL.9 binders, inorganic nanoparticles are incorporated homogeneously into organic polymer particles of water-based dispersions. These then form a three-dimensional network in the facade coating which ensures an extremely hard and hydrophilic surface(causing water to sheet) and a good balance between moisture protection and water vapor transmission. With Herbol-Symbiotec, falling water droplets wet the substrate evenly, meaning the facade dries faster and picks up less dirt. Similar paints containing TiO2 are manufactured by Behr, Valspar, and a number of others. Nanotec offers a range of nanocoatings with varying functionalities. Their Nanoprotect product creates a self-cleaning effect on glass and ceramic surfaces. They report that nanoparticles in Nanoprotect adhere directly to the material molecule and allow the surface to deflect dirt and water. Self-cleaning windows were one of the first architectural applications of nanotechnology. The special hydrophilic coating on Pilkington Activ self-cleaning glass, for example, causes water to sheet off the surface, leaving a clean exterior with minimal spotting or streaking. Using daylight UV energy, the photocatalytic surface of
  • 28. Nanotechnology for Green Building © 2007 Dr. George Elvin 23 Pilkington Activ gradually breaks down and loosens dirt, allowing it to be washed away by rain or hosing.43 Nanocomposite polymer makes paint last longer Facades coated with Herbol-Symbiotec paint based on BASF’s nanobinder COL.9 display reduced dirt pick-up and improved color retention. (Source: BASF) According to one report, nanotech surface treatments for stainless steel can reduce cleaning time by 80 to 90 percent and protect against pitting corrosion and metal oxide staining. Permanent coatings with corrosion protective properties are available but are not offered as an aftermarket product, the report says, and the average lifetime of such treatments is between 1 and 3 years. Certain application and curing processes require special devices and machinery which can only be offered during manufacturing. It is certain, the report concludes, that the products under development will replace the powder coating processes now widely used for corrosion protection.44 3.2 Anti-stain coatings In 2002, Eddie Bauer apparel became the first brand to employ Nano-Tex stain resistance technology in its designs. Protests by Topless Humans Organized for
  • 29. Nanotechnology for Green Building © 2007 Dr. George Elvin 24 Natural Genetics (THONG) at the Eddie Bauer flagship store in Chicago soon followed, but today the clothier continues to expand its nano-enhaced line, and Nano- Tex has expanded to bring stain resistance to fabrics and other interior finishes. HON Company, KnollTextiles, Mayer Fabrics, Arc-Com, Architex, Carnegie, Designtex, and Kravet all employ Nano-tex in their textiles. Unlike conventional methods that coat the fabric, claims Nano-Tex, they use a process that bonds to each fiber, making textiles last longer, retain their natural hand, and breathe normally. This means that solid colors, lighter fabrics and delicate weaves can be used in places where spills and stains are likely. Nanoprotex by Nanotec is a water-based impregnator with very high penetration depth for textile. The product is repellent to water, and the adherence of foreign matter to the surface is decreased. The nanoparticles adhere directly to the substrate molecules, deflecting any foreign matter.45 P2i produces Ion Mask enhancement for many applications, including aircraft cabin trim, seats, carpets and uniforms. Originally developed as a military technology to protect soldiers from chemical attack, Ion Mask applies a protective layer, just nanometers thick, over the surface of a material by means of an ionized gas or plasma. Without changing the look, feel or breathability of the fabric, the treated material becomes hydrophobic (water-resistant), making coffee and red wine spills roll off the surface like beads of mercury.46 Anti-stain technology is also available from CG2 . They incorporate ceramic nanoparticles that bond with the underlying material to create strong chemical forces which they say are around one million times more powerful than the purely physical interaction that is present in coatings made using standard mixing or deposition techniques. The particles can be designed for different capabilities such as anti- adherence, scratch resistance, reduced friction, and corrosion resistance. The addition of only 3 percent silica nanoparticles, they report, can increase abrasion resistance by approximately 400 percent, while using 10 percent silica resulted in an increase of approximately 945 percent.47 G3i has introduced GreenShield, a soil- and stain-repellent textile finish produced using the principles of green nanotechnology. According to the company, the manufacturing process eliminates waste and uses ambient temperature and pressure as well as water-based solvents, minimizing the use of environmentally detrimental chemistries and reducing the amount of product needed to deliver desired properties. The company reports the new finish reduces the use of liquid- and stain-repelling fluorochemicals by a factor of 10 by using what it calls the principle of micro- and nano-roughness, which creates a pocket of air between the liquid or stain and the fabric, thereby preventing penetration into the fabric. GreenShield, they say, also safely provides antimicrobial properties and antistatic properties.48 LuxShield coating for Luxrae Decking protects by controlling moisture, heat and water content, UV radiation, and stains. LuxShield coating, says it manufacturer, will
  • 30. Nanotechnology for Green Building © 2007 Dr. George Elvin 25 not diminish when exposed to the harsh elements. “LuxShield coating is not a sealer,” they say. Instead, its nanoparticles adhere directly to the substrate’s molecules and assemble into an invisible, ultra-thin nanoscopic mesh that provides an extremely long lasting hydrophobic surface. The hydrophobic effect creates an easy to clean protected surface with self-cleaning properties. All foreign particles are washed off by rain or when rinsed with water. LuxShield coating is non-toxic, environmentally-friendly, and UV-stable. It is, they say, resistant to friction and cannot be removed by water, normal cleaning agents, or high pressure equipment.49 Zirconia nanoparticles are graffiti’s demise Graffiti is an expensive social phenomenon, costing about $1.50 to $2.50 per square foot to clean. Last year alone the London tube spent over $15 million and the City of Los Angeles $150 million for graffiti cleanup. Those costs could go way down, along with the harmful effects of solvents used in the cleanup, thanks to new nanocoatings developed by Professor Victor Castaño, Senior Research Consultant at CG2. Dr. Castaño and his associates developed a novel approach using nanotechnology to chemically attach zirconia, a hard ceramic, to a typical polymer (PolyMethylMethAcrylate). In their process, ceramic nanoparticles are chemically “grown” on top of the polymeric surface, creating a “ceramic” surface to the exterior, with a much higher wear resistance. A coating of just 130 nm, which is 99.9 percent transparent, passed through an ASTM 500 series wear test, demonstrated an improvement of over 55 percent compared to uncoated surfaces.50 Nanoprotect AntiG is a water-based anti-graffiti nano-treatment suitable for concrete, brickwork, sandstone, travertine, granite, natural cast stones, and mineral plaster. The treatment consists of a permanent impregnating undercoat and a semi-permanent topcoat. Graffiti, says the manufacturer, can be easily removed by low-pressure hot water, without the need for harsh detergents and chemicals.51 3.3 Depolluting surfaces Self-cleaning surfaces enabled by nanotechnology offer energy savings by reducing the energy consumed in cleaning building facades. They also reduce the runoff of environmentally hazardous cleansers. As surfaces self-clean, they are “depolluting”, removing organic and inorganic air pollutants like nitrogen oxide from the air and breaking them down into relatively benign elements.
  • 31. Nanotechnology for Green Building © 2007 Dr. George Elvin 26 Depolluting nanocoatings show considerable promise in cleansing indoor air and reducing instances of sick building syndrome (SBS). The World Health Organization estimates that up to 30 percent of new or renovated energy-efficient buildings may suffer from SBS.52 The EPA estimates that SBS costs the U.S. economy $60 billion per year in medical expenses, absenteeism, lost revenue, reduced productivity and property damage.53 Self-cleaning nanocoatings shed dirt through photocatalysis Nanocoatings containing titanium dioxide (left) can be self-cleaning as compared to untreated surfaces (right). (Source: AVM Industries, Inc.) MCH Nano Solutions, for example, recently introduced Gens Nano, which the company describes as a new easy to apply, green, environmentally friendly, transparent coating for exterior applications. Gens Nano uses titanium dioxide nanoparticles to keep the building exterior clean and at the same time purify the air near and on the surface by breaking down nitrous oxides, formaldehyde, benzene, and VOCs.54
  • 32. Nanotechnology for Green Building © 2007 Dr. George Elvin 27 A current drawback to self-cleaning photocatalytic coatings utilizing titanium dioxide, however, is that they require sunlight for activation, reducing their effectiveness indoors. As an alternative for indoor applications, coatings using layered double metal hydroxides (LDH), air-cleaning nanocrystals, can be applied to indoor surfaces to improve the indoor climate and reduce ventilation requirements, thereby improving the building’s energy efficiency.55 To help overcome the current outdoor-only limitation of titanium oxide, researchers at the Institute for Nanoscale Technology in Sydney, Australia, are developing a variation that is activated by a standard lightbulb.56 Outdoors, photocatalytic coatings like the ones used in the Jubilee Church in Rome suggest the possibility of smog-eating roads and bridges for reducing outdoor air pollution. The Swedish construction giant Skanska is now involved in a $1.7 million Swedish-Finnish project to develop catalytic cement and concrete products coated with depolluting titanium dioxide.57 3.4 Scratch-resistant coatings Buildings are subjected to a great deal of wear and tear. Surface scratches can reduce the lifespan of many materials and add to the cost and energy required for maintenance and replacement. The susceptibility of many metals, wood, plastics, polymers and glazings to scratching can limit their potential applications in many areas. Nanocoatings can significantly reduce wear and surface scratches. Scratch-resistant nanocoatings are already common in the automotive industry. The 2007 Mercedes-Benz SL series, for example, sports a protective coating of nanoparticles that provides a three-fold improvement in the scratch resistance of the paintwork. DuPont is also working on nanoparticle paint for autos. The paint, licensed from Ecology Coatings, is cured using UV light at room temperature, rather than in the 204º C (400 º F) ovens required for conventional auto paint. "After the UV hits it, it becomes a thin sheet of plastic," explained Ecology Coatings co-founder and chief chemist Sally Ramsey in a recent interview. "Abrasion-resistance and scratch-resistance is very much enhanced." "We are in the early stages of a profound industry change," added Bob Matheson, technical manager for strategic technology production at DuPont. He estimates the technology will reduce the amount of energy used in the coating-application process by 25 percent and reduce materials costs by 75 percent. 58 Ecology Coatings makes coatings for metals, polycarbonates, and composites, and has also devised a method for waterproofing paper with nanoparticles. In 2005, the company granted a license to Red Spot Paint & Varnish to manufacture and sell its product in North America.59
  • 33. Nanotechnology for Green Building © 2007 Dr. George Elvin 28 Diamon-Fusion International (DFI) offers a patented scratch-resistant nanocoating tested and approved by a U.S. Army prime contractor, PAS Armored, Inc., for glass and other silica-based surfaces in military vehicles. The coating, they say, will improve vehicle safety under a wide range of adverse weather conditions. DFI’s nanocoating also integrates an antimicrobial property by inhibiting the growth of mold and bacteria on the treated surface. Like many of the nanocaotings described here, the DFI coating is multi-functional, incorporating water and oil repellency, impact and scratch resistance, protection against graffiti, dirt and stains, finger print protection, UV stability, additional electrical insulation, protection against calcium and sodium deposits, and increased brilliance and lubricity. DFI’s hydrophobic nanotechnology can also be found in Moen’s Vivid Collection, a new line of luxury faucets and accessories for kitchens and baths, where it will help guard against watermarks and deposits. 60 Triton Systems manufactures NanoTuf coating, a clear protective coating for polycarbonate surfaces. NanoTuf coatings are created from a solution of nanometer- sized particles suspended in an epoxy-containing matrix. They are specifically designed to coat and protect polycarbonate surfaces such as eyewear, making them up to four times stronger than existing polycarbonate coatings.61 Move over diamond: carbon nanorods are world’s hardest substance Diamond is no longer the world’s hardest material. Researchers at the University of Bayreuth in Germany have created an even harder material they call aggregated carbon nanorods. They made the new material by compressing super-strong carbon molecules called buckyballs to 200 times normal atmospheric pressure while simultaneously heating them to 2226° C (4719° F). The new material is so tough it even scratches normal diamonds.62 3.5 Anti-fogging and anti-icing coatings Titanium dioxide becomes hydrophilic (attractive to water) when exposed to UV light, making it useful for anti-fogging coatings on windows and mirrors. G-40 Nano 2000 by AVM Industries is an example of a product using this technology. Polymer coatings made of silica nanoparticles can also create surfaces that never fog, without the need for UV light. This coating also reduces reflectivity in glazed surfaces. The fogging of glazed surfaces is due to condensation. Condensation occurs when warm, humid air contacts a cold surface; the moisture in the air condenses and forms a layer on the colder surface. Condensation can be prevented by heating the cold surface. A team of researchers at the Fraunhofer Technology Development Group
  • 34. Nanotechnology for Green Building © 2007 Dr. George Elvin 29 TEG in Stuttgart, Germany have developed a nanotechnology that warms the surface with a transparent coat of carbon nanotubes. When electrically charged, the coating acts as a continuous heater uniformly covering the cold surface without wires of other visible heating elements.63 Nanocoatings can also help reduce the buildup of ice. CG2 makes an anti-icing coating that could offer improved environmental performance compared to heating, salts or chemicals often used to remove ice. According to the company, their product is an economical anti-ice coating that in independent tests demonstrated a reduction in ice adhesion by a factor of approximately four in comparison to bare aluminum. Potential uses include any application where even a relatively small reduction in ice adhesion is valuable and where a large surface area has to be coated.64 3.6 Antimicrobial coatings Many of the multifunctional coatings already mentioned incorporate antimicrobial properties. Others are marketed specifically for their antimicrobial properties. Antimicrobial products are marketed in sprays, liquids, concentrated powders, and gases. The U.S. Environmental Protection Agency says that approximately $1 billion each year is spent on antimicrobial products. Conventional antimicrobial products can contain any of about 275 different active ingredients, including biocides, which may release into the environment. Some biocidal ingredients in antimicrobial products pose both environmental hazards and indoor air quality concerns. Antimicrobial nanocoatings reportedly offer the benefits of conventional antimicrobial products without these environmental and health concerns. Bioni, for example, offers nanocoatings with a combination of antimicrobial and heat deflective properties. Their low thermal conductivity and the ability to reflect up to 90 percent of the sun’s rays reduce heat absorption in coated walls, thereby reducing air conditioning and energy consumption.65 Researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM in Bremen and at Bioni CS have developed a process for binding antibacterial silver nanoparticles permanently to paint. According to Bioni, the coating is certified as emission-free, and can destroy antibiotic-resistant bacteria. They report that their coating has been used in more than 20 hospital projects in Europe and the Gulf region, including the 40,000 square meter Discovery Gardens project in Dubai. As with nanocoatings from other manufacturers, Bioni can “cross-link” a variety of nanoparticles to add additional functionality such as UV protection and improved wear resistance to their antimicrobial coating. Mirage Hardwood Floors of Canada currently uses these cross-linked nanocoatings.
  • 35. Nanotechnology for Green Building © 2007 Dr. George Elvin 30 End of the line for subway-riding germs "Public transportation is a very common way, we know, of how diseases ... spread," said Ben Mascall, spokesman with MTR Corp., which operates the railway in Hong Kong and has bid for two new rail franchises in the U.K. In response, his company has coated its cars' interiors with titanium and silver dioxide nanocoatings that kill most of the airborne bacteria and viruses that come into contact with them. The London tube will soon do the same. Many surfaces that people touch every day in a subway carry thousands of bacteria and germs. With news of powerful flu strains like avian flu and hand-transmissible diseases like colds, public transportation operators like these pioneers are considering using new nano-enhanced disinfectants in their subways. Hong Kong is among the first cities to apply silver-titianium dioxide nanocoating to subway car interiors. Preliminary tests show the disinfectant reduced the presence of bacteria by 60 percent.66 BioQuest Technologies is marketing its BioShield 75, a nanotech- and water-based antimicrobial with no poisons, as a preventative product for use in homes and businesses in hurricane paths. Proactive application, they suggest, will reduce bacteria and provide an effective solution to microbial problems that continue to exist in homes and businesses after hurricane damage.67 Antimicrobial nanocoatings can also be incorporated into ceramic surfaces. The German plumbing-fixture manufacturer, Duravit, for example, has teamed with Nanogate Technologies to develop a product called Wondergliss. Wondergliss coating is fired over traditional ceramic glazing to create a surface so smooth that dirt, germs, and fungus cannot stick to it. In addition, water beads up and runs off the hydrophobic surface without lime and soaps being able to build up.68 Many paints contain nanoparticles (commonly titanium dioxide) to prevent mildew, including Zinsser’s Perma-White Interior Paint, Behr Premium Plus Kitchen & Bath Paint, and Lowe’s Valspar.
  • 36. Nanotechnology for Green Building © 2007 Dr. George Elvin 31 Plumbing aint what it used to be Microban International offers Microban, which they call the first antimicrobial polymeric, a plastic resistant to germs, molds, yeast, and mildew. Microban is used in more than 450 products ranging from cleaning supplies, paints and caulking to medical products, plumbing fixtures, and other kitchen and bath products. Their product, they say, does not wash or wear off of its material substrate. As one reviewer of the technology put it: “It is easy to imagine this technology producing piping so smooth that it would have little or no friction loss, which would lead to smaller piping able to carry many more gallons of water at the same working pressure as today’s piping. Or drain pipe so smooth and slippery that it cannot plug up. Or pipes that never wear out. Someday, entire plumbing systems may follow nature’s design of a living system. Imagine a water piping system that could change its dimensions based on the flow demand and available pressure like our own circulatory systems. Septic tanks could generate electricity as they digest waste. Plumbers in the future will no doubt look back and wonder how we got by with such primitive materials and tools. Truly, plumbing aint what it used to be and it never will be again.”69 Nansulate LDX from Industrial Nanotech is designed to encapsulate lead-painted surfaces, making them inaccessible by providing an overcoat barrier. At the same time, it provides mold resistance, thermal insulation, and protection against corrosion. Three out of four homes built prior to 1978 contain lead-based paint, and according to the EPA, residential lead abatement has cost $570 billion and commercial $500 billion. In the past fifteen years, encapsulation as an abatement technique has become a cost-effective alternative solution, typically costing 50 to 80 percent less than lead paint removal and replacement.70 Researchers at Yale University have found that carbon nanotubes can kill E. coli bacteria. In their experiments, roughly 80 percent of these bacteria were killed after one hour of exposure. The researchers said nanotubes could be incorporated during the manufacturing process or applied to existing surfaces to keep them microbe-free. The researchers also recognized that since nanotubes can kill bacteria, they could have a major impact on ecosystems. "Microbial function is critical in ecosystem sustainability and we rely on microbes to detoxify wastes in environmental systems," said Joseph Hughes of Georgia Tech. "If they are impaired by nanotubes, or other materials,” he concluded, “it is the cause for significant concern."71 The EPA now regulates nano- products sold as germ-killing, believing they may pose unanticipated environmental risks.
  • 37. Nanotechnology for Green Building © 2007 Dr. George Elvin 32 3.7 UV protection Ultraviolet (UV) light can break down many building materials. Wood, for example, is a desirable, renewable building material; it can be recycled and regenerated, and as a structural material, it can reduce heating and cooling loads because it is 400 times less conductive than steel, and up to 20 times less than concrete. It is also the only building material that takes in carbon dioxide and releases oxygen as it grows, working to counter the effects of carbon emissions. And it contributes far fewer of these emissions than its non-renewable counterparts, steel and concrete. But wood must be protected from environmental forces including water, pests, mold and UV radiation. When the use of wood-preserving chromium copper arsenate was discontinued for residential uses (in “pressure-treated” lumber) in 2003 due to environmental concerns, the wood industry began searching for cost-effective, long-lasting, antimicrobial products that would allow wood to perform well in outdoor applications. Today, nanocoatings are proving to fill that gap. Nanoscale UV absorbers added to protective coatings can help keep substrates from being degraded by UV radiation. The result is wood that lasts longer with less graying than unprotected wood. And the small size of the particles makes it possible to offer high protection without affecting the transparency of the coating. Nanovations Teak Guard Marine is one example of UV protection for wood. Nanovations provides sustainable wood protection solutions for Teak and other hardwoods.72 Many other materials can be protected by nanoparticles as well. SportCoatings makes a colorless, odorless Sports Antimicrobial System (SAS) based on AEGIS Microbe Shield, recently tested on synthetic turf fields, sports medicine training rooms, locker rooms, whirlpools, and wrestling rooms at Virginia Tech. “You could tell it worked quickly,” said Denie Marie, Facilities Manager of Virginia Tech’s Rector Field House. “Within 24 hours of the application it erased the typical locker room scent. It brought a noticeable freshness to our facilities.” SAS provides an invisible layer of antimicrobial protection they say will not leach any chemicals or heavy metals into the environment and will not rub off onto a player’s skin.73 Suncoat makes multifunctional adhesive films and “nano-adhesive transparent varnish” for UV protection of awnings and window glass. They say their product allows protected surfaces to maintain color quality over a longer period of time, shed dirt, resist scratches, and self-clean.74 Centrosolar Glas makes Solarglas Clear and Solarglas PRISM glasses that can be supplied with nano-coated anti-reflective properties.75 Advanced Nanotechnology Limited's NanoZ product is a zinc oxide nanopowder coating that the company claims provides superior UV protection and anti-fungal properties to wood and plastic surfaces. At the nanoscale, zinc-oxide particles are invisible, enabling the creation of transparent varnishes with the same enhanced
  • 38. Nanotechnology for Green Building © 2007 Dr. George Elvin 33 functionality of colored coatings. NanoZ is used, among other things, to provide UV protection in Bondall Paints.76 Tekon makes chemical-free treatments for keeping kitchens, baths, stone, glass, and countertops clean. Their sealing products protect surfaces from viruses, germs, bacteria, mold, and other harmful toxins. Tekon’s Bath, Stone, Countertop, and Stainless Steel Kits clean, protect and maintain surfaces in kitchens and bathrooms.77 Seal America sells a variety of nano-based sealants for wood, stone, tile, fabric, masonry, metal and concrete which they say are non-toxic and have no negative effects on human health or the environment.78 Finally, AVM Industries offers nine multifunctional nanocoatings for metal, wood, concrete and glass.79 Research currently underway in universities will add even more functionality to the range of UV-protectant products already available. Researchers at the School of Forest Resources and Environmental Science at Michigan Technological University, for example, have discovered a way to embed organic insecticides and fungicides in plastic beads only about 100 nanometers across. Suspended in water, the beads are small enough to travel through wood when it is placed under pressure. Their technology has been licensed to the New Jersey-based company Phibro-Tech.80 Recent patents for protective nanocoatings include “Interior protectant/cleaner composition,” by Hida Hasinovic and Tara Weinmann.81 3.8 Anti-corrosion coatings The cost of corrosion in the U.S. is estimated at $276 billion per year. In the Federal Republic of Germany, 4 percent of the gross national product is lost every year as a result of corrosion damage. Corrosion takes a toll not only on steel structures, but on concrete ones, which require steel reinforcing. In fact, 15 percent of all concrete bridges are structurally deficient because of corroded steel reinforcement.82 For protecting metal surfaces from corrosion, chrome plating is becoming an increasing concern because of the negative health and environmental effects of chromium.83 But corrosion can be reduced by coating materials with chemically resistant nanofilms of oxides. CG2 is one of several manufacturers marketing corrosion-resistant nanocoatings. Their technology consists of homogeneous thin films using alkoxides with chemically attached ceramic nanoparticles.84 Another system, Corrpassiv Primer epoxy by Ormecon, displayed “the best filiform corrosion results in the history of the institute,” in a study by the FPL Research Institute for Pigments and Paints in Stuttgart. Corrosion protection with Ormecon also offers environmental benefits by incorporating organic metals that are free from heavy metals. This makes it possible to replace not only lead compounds, chromate treatments and chromate, but also the zinc-rich coatings that will in the future be classified as containing heavy metals.85
  • 39. Nanotechnology for Green Building © 2007 Dr. George Elvin 34 Bonderite NT is said to be suitable for surface pretreatment for all conventional powder and wet paint coatings. It can be applied by dipping or spraying and creates a cohesive, inorganic, high-density layer incorporating nanoparticles. Measurements have shown that the nanoceramic coating delivers markedly better corrosion protection and paint adhesion than iron phosphating. Bonderite NT coatings do not require bath heating, and can be applied at room temperature, thus saving energy. They also offer significant environmental benefits. In addition to its low energy needs, Bonderite NT is distinguished by its lack of organic ingredients. Neither phosphates nor toxic heavy metals have to be disposed of, which means that far less sludge is generated in production. Outlay on wastewater treatment, waste disposal and plant cleaning and maintenance is significantly reduced.86 Ormecon has also released Organic Metal Nanofinish, a solderable surface finish for printed circuit boards, a technology that could be applied to architectural metals in the future. This new process consumes less than 10 percent of the energy compared to other metallic finishes, and promises to save more than 90 percent of raw materials.87 Integran makes nanoPLATE Coatings, nanostructured metal coatings with properties that meet or exceed those of hard chrome, including wear resistance, corrosion resistance, coefficient of friction, and also allow for the complete elimination of chromium.88 Nanocoatings offer superior corrosion resistance NanoPlate coatings (yellow) provide significantly greater corrosion resistance than HVOF (green) and hard chrome (blue) finishes, at half the thickness. (Source: Integran) NH 2015, available from Nanovations, is an oil-free, nanotechnology-enhanced surface treatment. Its makers report that it easily removes all staining and soiling and leaves behind a clean surface that is water and dirt repellent. It protects stainless steel against contamination for up to two years, even if fully exposed to weathering or harsh 0 500 1000 1500 2000 exposure time (hrs) astm b537 ranking 10 0
  • 40. Nanotechnology for Green Building © 2007 Dr. George Elvin 35 environments. During the lifetime of the coating, they say, maintenance is reduced to wiping the surface with a wet cloth. It is also VOC- and acid-free.89 On the research front, scientists in India have devised a method to protect copper from corrosion by coating it with conducting polymers. Their poly(o-anisidine) coatings reduce copper corrosion by a factor of 100.90 3.9 Moisture resistance Resistance to moisture penetration is critical to the durability of construction materials. Moisture causes rot in susceptible materials and feeds harmful mold and bacteria. Unfortunately, many conventional waterproofing materials, such as polyurethane, give off harmful volatile organic compounds (VOCs) as they cure. Nanocoatings, in contrast, provide moisture resistance without these harmful side effects. IAQM's Nano-Encap is a breathable antimicrobial sealant that protects wood, sheet rock and other porous materials from moisture. According to its manufacturer, Nano- Encap encapsulates any mold spores that might have settled on building materials and prevents future mold growth. Made up of cross-linking polymers, Nano-Encap bonds itself to the cellulose in wood and paper, eliminating mold's nutrient sources. This clear semi-gloss waterproofing protectant also keeps the treated surface cleaner than its original state and dissipates any moisture present in the material at the time of application.91 Water is a principal source of damage to concrete as well, and even dense, high- quality concrete does not eliminate absorption of water and soluble contaminates through capillary action and surface permeability. This can cause efflorescence and corrosion of the reinforcement. Nanovations offers a water-based micro emulsion, called 3001, for reducing water absorption in concrete. It can be applied to the surface or blended into the concrete mix. The result, says the manufacturer, is a low water absorptive concrete that is salt and frost resistant and cannot be affected by efflorescence, moss or algae. Its penetration properties, they add, are similar to or better than solvent-based solutions. 3001 is VOC- and odor-free, and can be applied in any situation without dangerous fumes. Users can avoid the impact of solvent-based formulas on the environment, including contributing to photochemical smog and occupational health and safety concerns.92 Hycrete is an integral waterproofing system that eliminates the need for external membranes, coatings and sheeting treatments for concrete construction. With the Hycrete Waterproofing System, concrete is batched with Hycrete liquid admixture to achieve hydrophobic performance. Concrete treated with Hycrete shows less than 1 percent absorption. Hycrete CEO David Rosenberg said in a Green Technology Forum interview that Hycrete transforms concrete from an open network of capillaries and cracks into an ultra-low absorptivity, waterproof, protective building material.
  • 41. Nanotechnology for Green Building © 2007 Dr. George Elvin 36 Hycrete also coats reinforcing steel surface with a monomolecular film while providing waterproofing properties to the concrete. It reacts with metals in the water, concrete, and reinforcement to form a precipitate that fills the capillaries of the concrete, repelling water and shutting down capillary absorption. The product is so environmentally safe it is the first material certified by Cradle-to-Cradle, a new program that evaluates and certifies the quality of products by measuring their positive effects on the environment, human health, and social equity. Reduced moisture absorption in concrete Hycrete, a Cradle-to-Cradle certified green nanomaterial for integral waterproofing, greatly reduces moisture absorption in concrete. (Source: Hycrete) Nanoprotect CS is a water-based solution with a very high penetration depth for concrete materials. The hydrophobic treatment, says its maker, is long lasting and can only be removed by damaging the surface.93 Another exterior coating, Lotusan, possesses a highly water-repellent surface similar to that of the lotus leaf. Its microstructure has been modeled on the lotus plant to minimize the contact area for water and dirt.94 Self-cleaning awning fabrics from Markilux are made of Swela Sunsilk Nano Clean, which its manufacturer says is extremely dirt, grease, oil and water repellent. The highly dirt repellent finish of the fabric, they add, offers UV protection and ensures long lasting radiant colors.95 Because of their vast market applications, water-repellent nanocoatings are a popular subject of university research as well, and many of these projects are available for license. Ohio State University engineers, for example, are designing super-slick, water-repellent surfaces that mimic the texture of lotus leaves for application in self- cleaning glass.96 Hong Kong University of Science and Technology has available, “Novel TiO2 Material and the Coating Methods Thereof.”97 Other licensable patents for waterproofing nanomaterials are available through the Engineering Technology control hycrete percent absorption 0 1 2
  • 42. Nanotechnology for Green Building © 2007 Dr. George Elvin 37 Transfer Center at the University of Southern California’s Viterbi School of Engineering.98 “Interior Protectant/Cleaner Composition” is an example of a recent patent in this area, combining natural camauba wax nanoparticles and zinc oxide nanoparticles with a quaternary siloxane compound. Its protectant composition cleans, protects, preserves and enhances the appearances of leather or vinyl surfaces used for covering items in the home or in vehicles. It dries quickly and leaves no oily residue behind.99 4. Adhesives While not the most glamorous technology, adhesives have revolutionized the construction industry. Construction adhesives were, in fact, voted the most significant technological advance of the last half of the 20th century in one survey of industry professionals. But many contain environmentally harmful substances like formaldehyde. Just as we saw with moisture-resistant coatings, however, nanotechnology promises a more environmentally friendly alternative. But consumers eager to adopt these eco-friendly super-adhesives will have to wait for their commercialization in construction. The Nano Adhesive Co. of Taiwan, for example, makes nanoadhesives, but only for the cosmetics and medical industries.100 Much of the inspiration for nano-enabled adhesives comes from nature. Adopting nature’s tricks is sometimes referred to as biomimicry. Examples of how nanoscientists mimic nature can be found in the water-repellent properties of nanocoatings, which take their lessons from the hydrophobic lotus leaf, and in a new generation of nano-adhesives now under investigation, which are based on the remarkable feet of the gecko, which enable it to climb walls and even ceilings. Several years ago researchers created nanotube surfaces that matched the gecko’s tenacious toes for stickiness, but how to unstick, and thereby create a useful product, has eluded scientists—until now. Researchers at Rensselaer Polytechnic Institute and the University of Akron have created synthetic gecko nanotube tape with four times the gecko’s sticking power that can stick and unstick repeatedly. The material could have applications in feet for wall-climbing robots, reversible adhesives for electronic devices, and even aerospace, where most adhesives don’t work because of the vacuum.101 The Center for Information Technology Research in the Interest of Society has also devised gecko-inspired adhesive nanostructures that will increase the capability of small robots to scamper up rocks, walls, and smooth surfaces.102 Researchers at Rensselaer Polytechnic Institute have devised a new adhesive for bonding materials that don’t normally stick to each other. Their adhesive, based on self-assembling nanoscale chains, could impact everything from next-generation computer chip manufacturing to energy production. “The molecular glue is inexpensive--100 grams cost about $35--and already commercially available,” said project leader Ganapathiraman Ramanath.103
  • 43. Nanotechnology for Green Building © 2007 Dr. George Elvin 38 Self-assembling nanoscale chains form nano-super- glue Researchers at Rensselaer Polytechnic Institute have developed a new method using self-assembling nanomaterials to bond materials that don’t normally stick together. (Source: Rensselaer/G. Ramanath) Researchers at the University of California, Berkeley, meanwhile, have developed biomimetically inspired nanostructures that can stick to wet, dry, rough or smooth surfaces, and can be peeled off and reused. These materials are also self-cleaning, leave no residue, and are bio-compatible. Their technology is available for licensing.104
  • 44. Nanotechnology for Green Building © 2007 Dr. George Elvin 39 Biomimicry: learning from the lotus leaf Through nanoscience and molecular biology we are learning more about how natural systems, organisms, and materials behave, and nanotechnology and biotechnology give us the tools not only to intervene in those systems, but to create new ones based on their capabilities. The lotus leaf is a good example. By studying its molecular makeup, scientists have unlocked its hydrophobic (water-repellent) properties and incorporated them into a new breed of materials capable of shedding water completely. The NanoNuno umbrella, for instance, dries itself completely after a downpour with just one shake. Developers are applying the hydrophobic properties of the lotus leaf in a wide range of products and materials from self- cleaning windows to car wax. Nature offers endless lessons that could be applied to future products, processes and materials. By examining the nanoscale structure of gecko feet, for instance, scientists have created gloves so adhesive a person wearing them can hang from the ceiling. All of these lessons will enable us to learn from nature to create systems, materials and devices that are less wasteful and more efficient than those available today. Nature does not waste, and through biomimicry we will learn to model our own systems with the efficiency, beauty and economy of natural systems. Scientists are even developing materials that adhere without the use of adhesives. Scientists at the Max Planck Institute for Metals Research in Stuttgart, Germany, have developed materials whose surface structure allows them to stick to smooth walls without any adhesives. The extremely strong adhesive force of these materials is the result of very small, specially shaped hairs based on the soles of beetles' feet. Their artificial adhesive system lasts for hundreds of applications, does not leave any visible marks, and can be thoroughly cleaned with soap and water. Potential applications include protective foil for delicate glasses and reusable adhesive fixtures. The new material will soon be used in the manufacture of glass components.105
  • 45. Nanotechnology for Green Building © 2007 Dr. George Elvin 40 Adhesion without adhesives Scientists have developed materials whose surface structure allows them to stick to smooth walls without any adhesives. (Source: Max Planck Institute for Metals Research) 5. Lighting Lighting and appliances consume approximately one third of the energy used in building operation. Not only do lighting fixtures consume electricity, but most produce heat that can add to building cooling costs. Incandescent lights, for example, waste as much as 95 percent of their energy as heat. Fluorescent lights use less energy and produces less heat, but contain trace amounts of mercury. Because of the heat generated by lighting, most office buildings run air conditioning when the outside air temperature is above 12°C (55°F). In fact, the cores of most buildings over 20,000 square feet require cooling even during the winter heating season.106 Because of this effect, every three watts of lighting energy conserved saves about one additional watt of air cooling energy.107 The energy-saving potential in more efficient lighting is therefore tremendous.
  • 46. Nanotechnology for Green Building © 2007 Dr. George Elvin 41 heating/cooling 44% lighting + other appliances 33% water heating 14% refrigerator 9% Residential energy consumption Lighting and other appliances (purple) consume one third of all energy in buildings (Source: US Department of Energy) 5.1 Light-emitting diodes (LEDs) One of the most promising technologies for energy conservation in lighting is light- emitting diodes (LEDs). In a global lighting market of $21 billion, the current market for high brightness LEDs exceeds $4 billion. Current uses of LEDs include civil works like traffic lights and signs, as well as some building applications like the facade of the Galleria Shopping Mall in Seoul by UN studio. Some LEDs are projected to have a service life of about 100,000 hours and offer the lowest long term cost of operation available. Potential energy savings from LEDs are estimated at 82 to 93 percent over conventional incandescent and fluorescent lighting. LEDs could save 3.5 quadrillion BTUs of electricity and reduce global carbon emissions by 300 million tons per year, potentially cutting global lighting energy demand in half by 2025. The principal obstacle to greater adoption of LEDs, however, is cost; they currently cost at least 10 times more than fluorescent ceiling lights. 108 Heat dissipation can be a problem with bright long-lasting LEDs, and the nanotech company, Celsia, is working with leading LED companies to develop LED cooling solutions. These include laminating their NanoSpreader technology with PCB film, so that LED circuitry can be attached to form an integrated cooler.109
  • 47. Nanotechnology for Green Building © 2007 Dr. George Elvin 42 Light-emitting diodes: always low prices! Wal–Mart expects to save $2.6 million in energy costs and reduce carbon emissions by 35 million pounds per year by using light- emitting diode (LED) refrigerated display lighting by GE. The retailer is outfitting refrigerated display cases in over 500 U.S. stores with the technology, and expects to net up to 66 percent energy savings, compared with fluorescent technology. Occupancy sensors and LED dimming capabilities will reduce the time the LED refrigerated display cases are at 100 percent light levels from 24 to approximately 15 hours per day.110 LED lighting uses one-third the energy Wal–Mart expects to save $2.6 million in energy costs and reduce carbon emissions by 35 million pounds per year with LED refrigerated display lighting. (Source: GE)
  • 48. Nanotechnology for Green Building © 2007 Dr. George Elvin 43 BridgeLux InGaN (indium gallium nitride) power-LED chips replace traditional bulb technologies with solid state products that provide a powerful and energy-efficient source of blue, green, or white light. BridgeLux chips are currently found in mobile appliances, signage, automotive, and various general lighting applications.111 Let there be light, but hold the heat PlexiLight, a startup out of Wake Forest University, plans to develop a new lighting source that is lightweight, ultra-thin, and energy efficient because it uses nanotechnology to produce visible light directly rather than as a byproduct of heating a filament or gas. Its unique properties suggest a wide range of residential and commercial applications. Light without heat “It looks like a sheet of plexiglass that lights up,” professor David Carroll says of PlexiLight, a new lighting source that may lead to heat-free lighting. (Source: Wake Forest University) Many other companies occupy the LED field, and opportunities for licensing abound. Two available nanotech-specific LED technologies are “Nanowires-Based Large-Area Light Emitters and Collectors,” from Harvard University, and “Luminescent Gold (III) Compounds, Their Preparation and Light-Emitting Devices,” from the Hong Kong University of Science and Technology.112,113 Recent patents in nano-enhanced LED
  • 49. Nanotechnology for Green Building © 2007 Dr. George Elvin 44 lighting include “Method for fabricating substrate with nano structures, light emitting device and manufacturing method thereof,” by Jong Wook Kim and Hyun Kyong Cho.114 PlexiLight has received startup funding from Wake Forest University and Connecticut-based NanoHoldings, which specializes in building early-stage nanotechnology companies around exclusive licenses from leading research universities. PlexiLight could target development of a substitute for the fluorescent ceiling light fixtures used in nearly all commercial buildings. The new technology may lead to higher-efficiency panels that would have no bulbs or ballasts to wear out and would not give off heat that requires additional energy to cool buildings.115 LEDs lead in lighting efficiency LEDs provide extremely efficient lighting—more than ten times that of today’s incandescent bulbs. (Source: Dowd, “Low Cost Hybrid Substrates for Solid State Lighting Applications,” Cleantech 2007, May 24, 2007, Santa Clara, CA) 5.2 Organic light-emitting diodes (OLEDs) Among the most promising nanotechnologies for energy conservation in lighting are organic light-emitting diodes (OLEDs). When electricity is run through the strata of organic materials that make up an OLED, atoms within them become excited and emit white led 150 hp sodium 132 metal halide 90 fluorescent 90 halogen 20 efficacy (lm/w) 0 50 100 150 200 incandescent 13
  • 50. Nanotechnology for Green Building © 2007 Dr. George Elvin 45 photons. OLEDs are highly efficient, long-lived natural light sources that can be integrated into extremely thin, flexible panels. Their introduction in the marketplace has so far been limited to small electronic components like cellphone displays, but their applications continue to grow in scale. OLEDs offer unique features like extreme flexibility, transparency when turned off, and tunability to produce variable colored light. OLED structure Organic light-emitting diodes (OLEDs) are highly efficient, long-lived natural light sources that can be integrated into extremely thin, flexible panels. (Source: HowStuffWorks.com) OLEDs could be used to create windows and skylights that mimic the look and feel of natural light after dark and could be applied to any surface, flat or curved, to make it a source of light. With this technology, walls, floors, ceilings, curtains, cabinets and tables could become light sources. Carbon nanotube-organic composites could even lead to structural panels capable of integrating lighting. This multifunctional ability of surfaces integrating OLEDs could lead to energy savings not only because OLEDs are more efficient than today’s lighting technologies, but by more efficiently integrating lighting into other building components. Scientists in Germany, for example, recently developed OLEDs that are transparent. Transparent OLEDs could be embedded into laminated glass, enabling windows to switch between transparent glazing and informational display panels, or act as both simultaneously. Universal Display Corporation is an OLED technology developer providing OLED manufacturers and product developers with phosphorescent, flexible, transparent and
  • 51. Nanotechnology for Green Building © 2007 Dr. George Elvin 46 top emission OLEDs. Their flexible organic light-emitting diode (FOLED) technologies apply to thin, lightweight displays that use little power and provide easy- to-read, vibrant color, transparency, and flexibility.116 FOLEDs make lighting flexible and efficient Flexible light-emitting diodes (FOLEDs) could free lighting and displays to bend with architectural surfaces. (Source: Universal Display Corporation) 5.3 Quantum dot lighting Quantum dots are nanoscale semiconductor particles that can be tuned to brightly fluoresce at virtually any wavelength in the visible and infrared portions of the spectrum. They can be used to convert the wavelength, and therefore the color, of light emitted by LEDs. Evident Technologies has developed technologies for dispersing quantum dots into a number of polymeric materials including standard LED thermal curing encapsulant materials (silicones and epoxies), injection moldable polymers, printable matrix materials, and semiconductor conjugated polymers. Their quantum dot composites can
  • 52. Nanotechnology for Green Building © 2007 Dr. George Elvin 47 be applied to LEDs, molded into fluorescent components and light guides, or printed onto any substrate.117 Quantum dot LEDs Quantum dot composites can be applied to LEDs, molded into fluorescent components and light guides, or printed onto any substrate. (Source: Evident Technologies) Displays from E Ink and LG Phillips are less than 300 microns thick, as thin and flexible as construction paper. Their prototype 10" screen achieves SVGA (600x800) resolution at 100 pixels per inch and has a 10:1 contrast ratio with four levels of grayscale. E Ink Imaging Film is a novel display material that looks like printed ink on paper and has been designed for use in paper-like electronic displays. Like paper, the material can be flexed and rolled. As an additional benefit, the E Ink Imaging Film uses 100 times less energy than a liquid crystal display because it can hold an image without power and without a backlight. They are 80 percent thinner and lighter than glass displays, and they do not break like glass displays.118
  • 53. Nanotechnology for Green Building © 2007 Dr. George Elvin 48 "This will completely change the way we use lighting" Carbon nanotube-organic composites may significantly reduce energy running costs, thus reducing carbon dioxide emissions at power generating stations. The Advanced Technology Institute (ATI) at the University of Surrey, for example, was recently awarded a £200,000 grant by the Carbon Trust to produce prototype solid state lighting devices using nano-composite materials. Their Ultra Low Energy High Brightness (ULEHB) technology may offer a cost- efficient and clean replacement for mercury based fluorescent lamps and many other low efficiency, heat producing light sources. Carbon nanotube lighting The Advanced Technology Institute is producing prototype solid state lighting devices like this Ultra Low Energy High Brightness (ULEHB) device using nano- composite materials. (Source: Advanced Technology Institute, University of Surrey)

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