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The goal of a building
investigation is to identify and solve indoor air quality complaints
in a way that prevents them from recurring and which avoids the
creation of other problems. To achieve this goal, it is necessary
for the investigators to discover whether a complaint is actually
related to indoor air quality, identify the cause of the complaint,
and determine the most appropriate corrective actions. It is often
necessary to evaluate feedback from building occupants prior to or
during the initial investigation. An example survey form is
available here:
Minnesota IEQ Survey Form.
An indoor air quality
investigation procedure is best characterized as a cycle of
information gathering, hypothesis formation, and hypothesis testing.
It generally begins with a walkthrough inspection of the problem
area to provide information about the four basic factors that
influence indoor air quality:
Preparation for a
walkthrough should include documenting easily obtainable information
about the history of the building and of the complaints; identifying
known HVAC zones and complaint areas; notifying occupants of the
upcoming investigation; and, identifying key individuals needed for
information and access. The walkthrough itself entails visual
inspection of critical building areas and consultation with
occupants and staff.
The initial walkthrough
should allow the investigator to develop some possible explanations
for the complaint. At this point, the investigator may have
sufficient information to formulate a hypothesis, test the
hypothesis, and see if the problem is solved. If it is, steps should
be taken to ensure that it does not recur. However, if insufficient
information is obtained from the walk through to construct a
hypothesis, or if initial tests fail to reveal the problem, the
investigator should move on to collect additional information to
allow formulation of additional hypotheses. The process of
formulating hypotheses, testing them, and evaluating them continues
until the problem is solved.
Although air sampling
for contaminants might seem to be the logical response to occupant
complaints, it seldom provides information about possible causes.
While certain basic measurements, e.g., temperature, relative
humidity, CO2, and air movement, can provide a useful "snapshot" of
current building conditions, sampling for specific pollutant
concentrations is often not required to solve the problem and can
even be misleading. Contaminant concentration levels rarely exceed
existing standards and guidelines even when occupants continue to
report health complaints. Air sampling should not be undertaken
until considerable information on the factors listed above has been
collected, and any sampling strategy should be based on a
comprehensive understanding of how the building operates and the
nature of the complaints.
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