Environmental Engineering Reference
In-Depth Information
The IR
λ
> 3000 nm radiation possibly improves the temperature in the
greenhouse in colder climates. The transmission rates for PAR by plastic
mulch can be modified by incorporating dyes/modifiers into the films
(Lamnatou and Chemisana, 2013).
Table 5.5
Greenhouse Glazing Materials and their
Characteristics
Source: Data from Both (2008) and Eugene A. Scales & Associates, Inc. (2003).
Transmittance (%)
Life (years) PAR
b
UV
c
IR R
a
Material
Glass
30+
90
60-70 <3 1.1
Acrylic (twin wall)
20
86
44
<3 1.67
Polycarbonate (twin wall) 10
75
18
<3 1.67
Polyethylene (one layer) 3-4
88
80
~50 0.91
a
The higher the
R
-value, the better the material is as thermal insulation.
5.4 BUILDING INDUSTRY APPLICATIONS
Buildingconstruction(thesecondlargestapplicationsectorafterpackaging)
accounts for 25-30% of plastic production worldwide, and the specific uses
of plastics in buildings are summarized in
Figure 5.4
.
The figure is based on
data compiled for 2005 in Europe, but the information is about the same for
the United States. In the United States, however, about 30% of the exteriors
of residential buildings are covered with vinyl siding. The most used plastic
in building construction is PVC with about 3/4th of the production used
in this sector. Products include pipes, fittings, cladding, flooring, ductwork
(rainwater goods), and window frames. These use the highest volume of
plastics followed closely by foam insulation. Most building products have a
long service life of several decades except for the floor/wall coverings and
fitted furniture. These latter items constitute the common building-related
waste in the municipal waste stream.
