Agriculture Reference
In-Depth Information
COMPOSITE MATERIALS . The use of moulded plas-
tics has seen some important developments in
the construction industry, whether that be in
the manufacture of doors, windows and shut-
ters or in the creation of terraces and swim-
ming pools.
17.6
Building Today, Tomorrow
and in the Future
This account of the possible uses of hemp in
the construction industry illustrates the enor-
mous potential of this material. This poten-
tial will only be realized if it does not fall foul
of the unavoidable hurdles presented by
today's economic, environmental and social
demands, as well as those of tomorrow and
the longer term.
Decking. Both low cost and ease of use have
seen hardwearing plastics used increasingly as
an alternative to wood as decking material. It is
used as a covering for verandas, terraces, gar-
den furniture and anything else that is exposed
to the elements. This market is well supplied
by a thermoplastic composite product that is
made using an extrusion process from 70%
sawdust, 25% polyethylene or polypropylene
and 5% additives. The European market turns
over some 30,000 t, while the US market turns
over 700,000 t per annum. A similar process
has been developed working with powdered
hemp as a raw ingredient.
17.6.1 Economic criteria
In economic terms, we need to take into
account the long-term competitiveness of ma-
terials, and therefore the overall cost of buildings -
their construction, upkeep and running costs.
We know, for example, that 80% of the energy
consumption of buildings is contributed by the
running costs, the remaining 20% being con-
tributed by the construction process. We do not
currently have enough information to say that
hemp-based materials will allow us to obtain a
construction/upkeep/running cost that is more
useful than that obtained using conventional
materials. It will also be necessary to analyse
the contributions made by hemp wool products
and hemp cement products separately. That
said, the trials under way and the testimony of
owners of homes made from hemp cement, or
of old homes whose walls have been rendered
with hemp-based plasters, are consistent and
tend to prove that these homes benefit from
superior thermal comfort over conventional
homes. This superior thermal comfort and the
lower ambient temperatures suggest that they
will result in substantial energy savings.
The cost of construction must not be over-
looked as, if it proves to be excessive, this will
hold back development. Here again, it is impor-
tant that hemp wool and hemp cement be con-
sidered separately. We have seen already that
the development of wools is linked very much to
their technical and economic competitiveness.
For hemp cement, the competitive objectives
are currently being met. While the volumes pro-
duced do not allow for substantial economies of
scale in the production of binding agents and in
bringing these products to market, and while
Hemp-based joinery. The global market for
windows produces some 6 million windows
a year and PVC frames have become very
popular in Europe. In most cases, these frames
will, of necessity, be reinforced with steel. This
market consumes 9000 km/year of extruded
product just for France. Today, we know how
to produce extruded products loaded with 30%
hemp with a rigidity comparable to the equiva-
lent steel and PVC products.
These doors and windows are lighter in
weight and have better insulating character-
istics, as they contain no thermal bridges.
They are also recyclable and competitively
priced.
Manufacturers in this sector are starting to
take a serious interest in this area and in these
products.
UNDERLAY . Hemp fibre that has been carded
and needled to form non-woven materials
has a number of uses. It can be used as under-
lay below floating floors or fitted carpets, as
well as under floating solid floors, and as
acoustic insulating material under floorboards
and cement.
TEXTILE . Furnishing materials such as mats
and carpets.
 
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