SOCIETAL BENEFITS OF PLASTICS - Plastics and Environmental Sustainability - page 198

less in labor costs compared to the use of metal pipes (cast iron and copper)
plumbing system (JB Engineering, 2006). The EE and GWP for the lighter
plastic pipes will be much lower than that for cast iron or copper pipes
in any event. Especially in developing countries, plastic pipe systems have
contributed to the availability of potable water to rural populations. For
potable water and hot water, CPVC, cross-linked polyethylene (XPE), or
PB pipes are used. These can withstand continuous operating temperatures
of approximately 80°C. Their susceptibility at high temperatures and
flammability isadisadvantage comparedtometalpipes.Conduitsthatcarry
electrical wiring as well as cable covering are also made out of rigid PVC.
5.4.2 Extruded PVC Cladding and Window Frames
A particularly popular low-cost choice (more than 50% of the market) of
cladding for exterior façade of residential units in the United States is rigid
PVCsiding.Accessoriessuchassoffitandfasciaaswellasrainwatersystems
are also usually made of the plastic and are gaining market share mainly
because of low cost and good performance relative to metal. Not only are
they lightweight, noncorroding, and easy to install, but they can also be
fabricated in a wide range of colors. An opacifier additive, usually rutile
TiO 2 filler, is used in PVC siding intended for use outdoors to control
light-induced yellowing discoloration or surface chalking damage on
extended exposure. Despite the stabilization afforded by pigment, the
lifetime of cladding is still limited by uneven yellowing discoloration and
surface degradation leading to “chalking.” Recent innovations include
lighter microfoam cladding and insulated PVC cladding with polystyrene
foam (EPS) backing. Including recycled content in cladding improves its
environmental characteristics. According to a leading manufacturer , 9
10-13% of the foam backing, 79-96% of the PVC, and <1% of the glue
in a foam-backed cladding are based on recycled material (including
postindustrial as well as postconsumer contributions).
The use of extruded rigid PVC windows and doorframes is common in
residential building practice in the United States. An estimated 3 MMT of
PVC (or about 8% of the production) is used in window- and door-frame
applications (Stichnothe and Azapagic, 2013). Comparisons of the
performance of PVC windows to aluminum or wood widows taking (Asif
et al., 2005; Citherlet et al., 2000) recycling into account (Stichnothe and
Azapagic, 2013), are published. Generally, wood and aluminum-clad wood