LBNL scientists, along with the DOE and other organizations, are working toward a method for scoring indoor air quality (IAQ). This score would be similar to energy scores like the HERS Index (HERS = Home Energy Rating Systems). The HERS Index rates homes from 150 down to zero — zero being the best rating and denoting that the home is a net zero energy home. Homes with higher IAQ scores would have more indoor air pollutants than homes with lower scores. With the IAQ index, 150 would represent a home with very poor indoor air quality and a zero would represent exemplary IAQ.
The Value of an IAQ Index
IAQ has great value to homeowners, builders, and energy auditors, and code and standard bodies. The SVACH project will develop new IAQ metrics that focus on managing IAQ to reduce the health risk of poor IAQ. The metrics will identify characteristics of the home that both increase and decrease IAQ risks.
To promote IAQ, the metrics will include health-based assessments using the contaminants of concern (COCs) as well as moisture and odor to address occupant perception and acceptability. The outcome from these metrics will be a score or index, rather than a standard for performance or a minimum level of performance. This allows flexibility for building codes and performance standards to set minimum performance targets.
IAQ Index Example
A standard IAQ scoring system or index could encourage better choices about IAQ and provide a way to reward building the industry for providing healthy, durable homes. IAQ index will also increase the value of pollutant measurements and could lead to real-time IAQ controls that effectively respond to indoor air pollutant levels.
IAQ Index – Determining Points
The magnitude of the points are based on the following three factors.
- The hazard type and level
- How much that an observable feature mitigates the hazard
- The usability, effectiveness, durability, and limitations of the mitigation strategy
Then you combine three separate sub scores as described above, those being health, odor, and moisture. The IAQ index with base health score on disability-adjusted life years (DALYS). Scores for odor and moisture would be less precise and more subjective.
- Use DALYs based on contaminants of concern and their likely concentrations
- Based on existing literature, plus current and soon to be started field studies
- Various indexes: mean RH, hours above RH limit, number of times above RH limit for more than 24 hours… etc.
- Adapt ASHRAE 160 Mold Index (currently LBNL using this in Attic study for CEC)
- Most sources are from occupants
- Could use CO2 or RH as a surrogate for bioeffluents?
Preventing Duplicate Scoring
Two mitigation strategies that mitigate the same hazard won’t each reduce the IAQ score. If the first strategy mitigates the hazard sufficiently, the second strategy is somewhat of a waste. Therefore the score doesn’t recognize the second strategy.
Current Status of the IAQ Index
- Combines hazard level with home mitigation features and mitigation feature effectiveness
- Effectiveness: for example measured air flows get a better score than non-measured systems
- Review by experts underway
- Volunteers needed to beta test the index