(163b) Biowall’s Impact on Indoor Air Quality and Energy

The average American spends more than 90% of his or her time indoors where the air is 2-5 times more polluted than outdoors. A principal cause of indoor pollution and its associated health concerns are volatile organic compounds (VOCs), which are emitted by a wide array of household products.  Taken as a whole, poor indoor air quality (IAQ) is estimated to cost the United States at least $40 billion annually due to related illness and lost productivity. The elderly and the young are especially at risk to illness due to lifestyle habits and weaker immune systems.

Energy efficient buildings typically seal the leakage paths for outside air infiltration but this can lead to poor IAQ as an unintended side effect. The Biowall is a new concept for maintaining high levels of indoor air quality and has the potential to reduce HVAC energy use by reducing outside air requirements for buildings. The device consists of a living plant filter that is integrated into the heating and cooling system of a residence or a small commercial building. This technology leverages the natural ability of plants to reduce CO2 and remove VOCs.  

To evaluate this concept, a living plant filter was designed and grown in a simulated building environment.  The plant filter was integrated with a heating and cooling system and fully instrumented so precise measurements of air temperature, air humidity, air quality, and component-level energy consumption could be made. Various growth media, plant varieties, and watering strategies were evaluated to investigate options for improving a Biowall’s performance. The experimental work involved introducing toluene, a common VOC in buildings, into a test chamber where precise measurements of the VOC decay rate could be made.  Comparisons were made with the toluene removal rate, both with and without the Biowall.