Environmental Engineering Reference
In-Depth Information
toilets, showers/tubs, laundries, and external faucets for lawn and garden
use. They also carry away cooking and bathing waters, toilet wastes, con-
densate from air conditioners and high-efficiency furnaces, and, in some
cases, food wastes. In most cases, plumbing systems perform their functions
well. Good maintenance, however, is required to prevent damage from leaks
(which are relatively common) and entry of sewer gases through drains that
develop dry traps. Plumbing-related problems that result from improper
installation or maintenance are common in many residences.
13. Other utilities
Other utilities that are integral parts of housing structures include electrical
wiring and, in many homes, pipe systems for natural gas or propane. Except
for the potential to cause structural fires, electrical wiring poses no environ-
mental concerns. Gas utility systems are subject to leakage and may cause
an odor problem; the odor is designed to warn homeowners that leaking
fuel gas may pose an explosion hazard.
E.
Age and condition
Buildings vary in age and condition, so they vary in the types and magnitude
of IAQ/IE problems associated with them. Because lead-based paint was
used to cover exterior surfaces prior to 1978, and both interior and exterior
surfaces prior to the 1950s, older houses are more likely to be contaminated
with lead-containing dusts. This problem is exacerbated by the fact that
many older houses are not well maintained; many are dilapidated.
Older houses are more likely to have had problems such as water intru-
sion, flooding, and condensation on windows and walls during their history
than new houses. As a consequence, they are at much higher risk of being
infested with mold.
Older houses are more likely to be less insulated, and therefore better
ventilated, than newer houses. As such, they have higher air exchange rates.
They are also more likely to have hardwood floors and less likely to have
wall-to-wall carpeting.
F.
Site characteristics
Inadequate site drainage bedevils many homeowners. Many building sites
were historically poorly drained and remain so after building construction.
Dwellings constructed on such sites are subject to a variety of water-related
problems, including: basement seepage or flooding; episodically wet crawl-
spaces; water in heating/cooling ducts in slab-on-grade houses; and infes-
tation of slab-on-grade ducts with moisture-loving crustaceans (sow bugs),
spiders, insects, and mold. The periodic incursion of moisture into base-
ments, crawlspaces, and slabs poses major IE problems. It may cause wetting
of materials and subsequent mold infestation; high indoor humidity which
increases the risk of condensation on cold window surfaces and a variety of
