Civil Engineering Reference
In-Depth Information
Warm air goes up and the temperature in the upper air layers of heated rooms is
always higher, which may cause a loss of heat through the roof. Insulating the
basement is also a very effective way to add energy efficiency. Insulating exposed
ductwork that runs through unheated areas, such as crawl spaces and attic, is
equally important (Extension
2001
).
Youngquist et al. (
1994
) has made an extensive review of vegetable fibres for
building materials and panels. The review covered a wide range of issues including
the methods for efficiently producing building materials and panels from vegetable
fibres, mechanical and physical properties of products made from them, use of
vegetable fibres as stiffening agents in cementitious materials and as refractory
fillers and cost-effectiveness of using materials. Many different kinds of vegetable
fibrous materials have been surveyed and grouped, by type of raw material, into
five major sections: panel boards including acoustical and thermal materials,
cement/clay/gypsum/plaster
materials,
moulded
masses,
miscellaneous,
and
material used in natural state.
In addition to general thermal properties described above, the appropriate
degree of insulation depends on local climate, building construction type, and
many other factors. Soubdhan et al. (
2005
) studied the influence of radiant barriers
on conductive and radiative heat transfers when they are integrated to a building
envelope and compared their efficiency to traditional insulation material (mineral
wools and polystyrene) under tropical climate. Different tests were performed to
evaluate the influence of parameters such as roof absorptivity and roof air layer
ventilation on the heat flux reduction through the roof. Pervaiz and Sain (
2003
)
reported the environmental performance of hemp-based natural fibre mat ther-
moplastics (NMT) by quantifying carbon storage potential and CO
2
emissions and
comparing the results with commercially available glass fibre composites. Non-
woven mats of hemp fibre and polypropylene matrix were used to make NMT
samples by film-stacking method without using any binder aid. They showed that
hemp-based NMT have compatible or even better strength properties as compared
to conventional flax-based thermoplastics and their impact energy values are also
promising. Hens and Janssens (
1998
) examined the performance of self-drying
roof in cool and cold climates.
With regard to structural behaviour, Bojic et al. (
2002
) studied the insulation
effects of including a thermal insulation layer in the fabric components that sep-
arate cooled spaces from the outdoors and from nonair conditioned spaces in high
rise residential buildings. The simulation results showed that the highest reduction
in the yearly cooling load and in the maximum cooling demand would be achieved
when a 50-mm-thick thermal insulation layer was placed at the indoor side of the
walls that enclose the cooled spaces. Fibre-based composite insulators have been
very popular for decades due to their good mechanical and thermal properties.
Abdou et al. (
1996
) investigated the thermal insulation characteristics of the
prefabricated, interlocking fibreglass composite panel system in the construction of
building envelope systems. The experiments showed that such envelope system
could be a potential candidate for wider use in energy-conscious commercial
buildings.
