Formaldehyde Concentrations in a Net-Zero Energy House: Real-time Monitoring and Simulation.

Measured real-time formaldehyde concentrations in a net-zero energy house were compared to simulated concentrations from a recently-developed, coupled building energy and airflow/indoor air quality model. Measured and simulated formaldehyde concentrations in living spaces ranged from 4 ppbv to 10 ppbv (5 μg/m3 to 12 μg/m3) while concentrations in the conditioned attic ranged from 13 ppbv to 28 ppbv (16 μg/m3 to 34 μg/m3). During the 15 minutes the heat recovery ventilator was off each hour, the measured concentration in a bedroom increased by 1 ppbv (1.2 μg/m3). In addition, year-long simulations suggest the formaldehyde concentration in the attic may reach almost 50 ppbv (62 μg/m3) during the summer. These results highlight the need for source control and effective ventilation (both outdoor air and air distribution) to reduce the concentration of indoor pollutants, particularly in tighter buildings. This research reaffirms the need to consider buildings as multizone systems and provide adequate ventilation to all building zones, particularly those with low outdoor air change rates.