Nanotechnology and Construction

Report on Nanotechnology and Construction
nanofibrils would lead to a new paradigm in sustainable construction as both the production
and use would be part of a renewable cycle. Some developers have speculated that building
functionality onto lignocellulosic surfaces at the nanoscale could open new opportunities for
such things as self-sterilizing surfaces, internal self-repair, and electronic lignocellulosic
devices. These non-obtrusive active or passive nanoscale sensors would provide feedback on
product performance and environmental conditions during service by monitoring structural
loads, temperatures, moisture content, decay fungi, heat losses or gains, and loss of
conditioned air. Currently, however, research in these areas appears limited.
Due to its natural origins, wood is leading the way in cross-disciplinary research and
modelling techniques which have already borne fruit in at least two areas. Firstly, BASF have
developed a highly water repellent coating based on the actions of the lotus leaf as a result of
the incorporation of silica and alumina nanoparticles and hydrophobic polymers. And,
secondly, mechanical studies of bones have been adapted to model wood, for instance in the
drying process.
In the broader sense, nanotechnology represents a major opportunity for the wood industry to
develop new products, substantially reduce processing costs, and open new markets for biobased
materials.
Nanotechnology and Glass
The European glazing market, which represents 45% of the worldwide market, reached a
volume of 80,000 units in 2001, at a sales volume of €18bn. The current state of the art in
cladding is an active system which tracks sun, wind and rain in order to control the building
environment and contribute to sustainability, but this is unreliable and difficult to calibrate
and maintain. Consequently, there is a lot of research being carried out on the application of
nanotechnology to glass and some of the most promising areas are outlined below as well as
some products that are already available.
Titanium dioxide (TiO 2 ) (box 2, p7) is used in nanoparticle form to coat glazing since it has
sterilizing and anti-fouling properties. The particles catalyze powerful reactions which
breakdown organic pollutants, volatile organic compounds and bacterial membranes. In
addition, TiO 2 is hydrophilic (box 4, p9) and this attraction to water forms sheets out of rain
drops which then wash off the dirt particles broken down in the previous process. Glass
incorporating this self cleaning technology is available on the market today.
Fire-protective glass is another application of nanotechnology. This is achieved by using a
clear intumescent layer sandwiched between glass panels (an interlayer) formed of fumed
silica (SiO 2 ) nanoparticles which turns into a rigid and opaque fire shield when heated.
Most of glass in construction is, of course, on the exterior surface of buildings and the control
of light and heat entering through building glazing is a major sustainability issue. Research
into nanotechnological solutions to this centres around four different strategies to block light
and heat coming in through windows. Firstly, thin film coatings are being developed which
are spectrally sensitive surface applications for window glass. These have the potential to
filter out unwanted infrared frequencies of light (which heat up a room) and reduce the heat
gain in buildings, however, these are effectively a passive solution. As an active solution,
thermochromic technologies are being studied which react to temperature and provide
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