Appendix C 443
operating conditions, such as conditions that leads to worst case IEQ.
In this instance, short-term measurements can be performed only under
these conditions.
8.5.4 Approach 4: Long-term Continuous
Measurements of Selected IEQ Parameters
Long-term continuous measurements are often affordable and
useful for tracking selected IEQ parameters including indoor tempera-
tures and humidities, carbon dioxide concentrations, carbon monoxide
concentrations, and rates of outside air intake into air handlers. For
most other IEQ parameters, long-term continuous measurements are
prohibitively costly or unavailable. The costs of sensors, and sensor
maintenance and calibration may be lower in continuous monitoring
systems that use single sensors to analyze samples drawn sequentially
from multiple locations, However, drawing some pollutants, e.g., par-
ticles and many VOCs, through long sampling tubes will lead to sub-
stantial measurement errors.
8.5.5 Approach 5: Surveys to Assess Occupant
Perceptions and Ratings of IEQ
In many instances, occupant perceptions determined in a survey
are as relevant an outcome as measured IEQ conditions. Survey costs
can be lower or higher than costs of physical measurements.
There are two basic uses of surveys in the context of IEQ M&V
First, administration of a survey before and after implementation of an
energy conservation measure can provide information on the perceived
change in IEQ and occupant reports of health symptoms^1. The second
method of using surveys in the context of IAQ M&V is to perform a
one-time survey and to compare the results to baseline data obtained
previously in other buildings with the same survey instrument.
Survey data are subjective; hence, these data may be influenced by
psychosocial factors such as job satisfaction. A portion of the occupants
may express dissatisfaction even when IEQ is above average. Addition-
- There is evidence that responses to surveys of non-specific health symptoms
tend to vary even with no apparent change in building conditions or IEQ.
Often, occupants report fewer building-related health symptoms on a second
of two surveys administered a week or two apart in time. Thus, it may be
necessary to correct the change in survey results obtained from the space
with the energy conservation retrofit by subtracting the change in survey
results from a control population.