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A. Hunter Fanney, Chief
Building Environment Division
(301) 975-5864
hunter.fanney@nist.gov

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Indoor Air Quality and Volatile Organic Compounds

Heat Recovery Ventilator (HRV) Airflow Rates

The airflow rates of the heat recovery unit used to provide outdoor air to the house are being measured to confirm it performs per the house design specifications. This unit brings outdoor air into the house and exhausts indoor air, with heat exchange between the two airstreams to reduce the energy needed to condition the outdoor air. The unit was sized to comply with the outdoor air requirements in ASHRAE Standard 62.2 Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, which for this building is about 38 L/s (80 cfm). The outdoor airflow rate provided by the HRV has been measured on several occasions and the results are consistent with this design value.

HRV unit
HRV unit and associated ductwork

VOC and formaldehyde

The building materials for the net-zero house were specified to have low emissions of volatile organic compounds (VOC), including a prohibition on products with any added formaldehyde. Indoor air samples have been collected and analyzed to determine the levels of about two dozen individual VOCs and formaldehyde in order to determine the impact of the building material specifications. These samples are being collected approximately monthly and will be used to determine VOC emission rates for the house and to determine if there are any changes over time. Additional samples need to be taken before the reliability of the measurements can be determined, but the concentrations appear to be quite low, particularly for formaldehyde.

VOC and formaldehyde sampling apparatus
VOC and formaldehyde sampling apparatus

Radon

Charcoal test kits were deployed to measure indoor radon concentrations in the house following the EPA Protocols For Radon and Radon Decay Product Measurements in Homes. These measurements were made in the basement, first floor, and second floor from Feb 15 to 19, 2013. All samples were below the EPA action level of 4 pCi/L. Additional measurements will be made throughout the year to determine if there are any seasonal variations in radon levels.

radon charcoal test kit
Radon charcoal test kit in basement