pollutants; Biological contaminants; Pollutants; Soil
contaminants; Water pollutants
2. Change of short-wave radiation (e.g. from
the Sun) to long-wave radiation when it strikes a
surface. The total amount of radiation striking a
surface equals the amount of energy absorbed
by the surface, plus the amount reflected off that
surface, plus the amount transmitted. For exam-
ple, photovoltaic cells absorb the Sun’s heat,
which can then be converted into electricity.
Water and moisture absorption in walls and
penetration through insulating materials has an
impact on building physics, and condensation
effects can result in mold.
Absorption cooling A cooling process, such as
an air conditioner, driven by a heat source such
as solar-heated water or natural gas, not by
electricity. As a solar cooling technique, absorption
cooling uses steam or an open flame to generate
cooling. It is most frequently used to air-condition
large commercial buildings. The use of solar energy
for cooling generates clean energy and sig-
nificantly reduces greenhouse gas emissions and
carbon dioxide emissions. For example, large,
high-efficiency, double-effect absorption chillers
using water as the refrigerant are common in the
Japanese commercial air-conditioning market.
There has been a growing interest in absorp-
tion cooling. In order to lower costs where peak
demand rates and overall electricity rates are
high, and natural gas prices are reasonable,
there may be increased use of absorption chil-
lers. For example, hotels are installing more
small, built-in absorption refrigerators, and recrea-
tional vehicles are using absorption refrigerators
because they do not require electricity.
Some of the negative effects of absorption
cooling include complexity of operation, increased
on-site pollutants if natural gas provides the
energy, and very high temperatures (possibly
>300 °F; >149 °C) to operate.
Because absorption chillers can make use of
waste heat, they can essentially provide free
cooling in certain facilities. Absorption cooling
systems can most easily be incorporated into new
construction, although they can also be used as
replacements for conventional electric chillers.
Absorption cooling has a coefficient of per-
formance (COP) of less than 1 (one). See also:
Coefficient of performance (COP); Solar cooling
Absorption heat pump See: Heat pump
Absorption process General term used by
designers for processes used in industrial plants to
remove gaseous contaminants and environ-
mental pollutants to minimize their emission into
the environment. See also:
Scrubbers
Accretion Build-up of sediment along the
bank or shore of a body of water such as a river
or stream. It can result in flooding of adjacent
areas if the sediment or loessial deposits impede
the natural flow of water and increase silting and
diversion of waterways. Silting can affect water
quality. Ecodesign tries to eliminate accretion as
it can significantly affect the aquatic ecology of
water bodies.
Acetone Major soil and air contaminant. It
evaporates easily, is flammable, and dissolves
in water. It is also called dimethyl ketone,
2-propanone, or beta-ketopropane. It is a com-
pound that is also found naturally in the envir-
onment. Acetone occurs naturally in plants, trees,
volcanic gases, forest fires, and as a product of
the breakdown of body fat. It is present in vehicle
exhaust, tobacco smoke, and landfill sites.
Acetone is used to make plastic, fibers, drugs,
and other chemicals. It is also used to dissolve
other substances. Industrial processes contribute
more acetone to the environment than natural
processes. Discharge onto the land and into mature
ecosystems leads to contamination and to
brownfield sites that will require decontamination
and rehabilitation. See also:
Soil contaminants;
Brownfield site
2 Absorption cooling