The Energy Audit 193tion air. A high level of carbon dioxide (e.g., 1000-10,000 ppm) is not a
problem in itself, but levels above 1000 ppm indicate concentrated hu-
man or combustion activity or a lack of ventilation air. Carbon dioxide
is useful as an indicator compound because it is easy and inexpensive
to measure.
Microbiological Contaminants
Microbiological contaminants generally require particular condi-
tions of temperature and relative humidity on a suitable substrate to
grow. Mold and mildew are inhibited by relative humidity levels less
than 50%. Air distribution systems often harbor colonies of microbial
growth. Many people are allergic to microscopic dust mites. Cooling
towers without properly adjusted automated chemical feed systems are
an excellent breeding ground for all types of microbial growth.
Ventilation Rates
Recommended ventilation quantities for commercial and insti-
tutional buildings are published by the American Society of Heating,
Refrigerating, and Air-Conditioning Engineers (ASHRAE) in standard
62.1-2004, “Ventilation for Acceptable Air Quality.” These ventilation
rates are for effective systems. Many existing systems fail in entraining
the air mass efficiently. The density of the contaminants relative to air
must be considered in locating the exhaust air intakes and ventilation
supply air registers.
Liability
Liability related to indoor air problems appears to be a growing
but uncertain issue, because few cases have made it through the court
system. However, in retrospect, the asbestos and urea-formaldehyde
pollution problems discovered in the last two decades suggest proceed-
ing with caution and a proactive approach.
CONCLUSION
Energy audits are an important first step in the overall process
of reducing energy costs for any building, company, or industry. A
thorough audit identifies and analyzes the changes in equipment and
operations that will result in cost-effective energy cost reduction. The