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 ppb_v to 10 ppb_v (5 microg/m³ to 12 microg/m³) while concentrations in the conditioned attic ranged from 13 ppb_v to 28 ppb_v (16 microg/m³ to 34 microg/m³). During the 15 minutes the heat recovery ventilator was off each hour, the measured concentration in a bedroom increased by 1 ppb_v (1.2 microg/m³). In addition, year-long simulations suggest the formaldehyde concentration in the attic may reach almost 50 ppb_v (62 microg/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.