Air Cleaning Performance of a Biowall for Residential Applications

An active botanical air filtration system, called the Biowall, is used to improve indoor air quality (IAQ) and provide the potential for energy savings in residential buildings by reducing the need for air conditioning. The Biowall is an integral part of the HVAC system to actively filter the return air from Volatile Organic Compounds (VOCs). The Biowall was recently evaluated in an environmental chamber with controlled conditions to measure its air cleaning characteristics. A ‘pull-down’ test method, in which a known amount of contaminant was introduced to the chamber so that its decay could be monitored over time, was used for the evaluation. The decay rate of the contaminants with the Biowall present was then compared to the decay rate of an empty chamber and the growth media alone (without plants). The experiments also evaluated the filter at different airflow rates across the filter and different moisture content inside the growth media. Based on the experimental data, the clean air delivery rates (CADR) of the Biowall were quantified. The preliminary results showed that the Biowall removed up to 90% of the introduced contaminants within two to three hours inside a sealed environmental chamber. This could potentially translate into energy savings on the ventilation systems of up to 25%. In addition to savings on ventilation, the Biowall could contribute in saving heating and cooling energy by reducing the air temperature during summer months, and reducing the air dryness during the winter months. Beyond these quantifiable benefits, a Biowall provides an intangible benefit by adding a pleasant natural aesthetic to a home.