ABSTRACT
Biofilter living walls (biofilters) have emerged as a sustainable solution to improve indoor air quality, reduce energy consumption, and mitigate CO2 emissions. This white paper delves into the scientific findings from a study conducted by the National Research Council of Canada, highlighting the efficiency of biofilters in volatile organic compound (VOC) removal, the underlying mechanisms, and the significance of real-world testing parameters. This specific study used the Respira biofilter developed by New Earth Solutions to collect the following findings.
INTRODUCTION
Biofilter living walls integrate and optimize the biologically active root zone of plants and have shown effectiveness in filtering indoor air pollutants. Beyond aesthetics, they offer tangible health and environmental benefits, including reduced energy consumption and enhanced indoor air quality.
THE SCIENCE BEHIND BIOFILTERS
Role of Diverse Plant Species
Diverse plant species in biofilters provide varied metabolic pathways, ensuring a broader spectrum of VOCs can be metabolized and removed. Each plant species, with its unique metabolic processes, targets specific VOCs, enhancing the system’s overall efficiency.
Microbial Adaptation and VOC Removal
Microbes in biofilters adapt to contaminants over time, leading to improved VOC removal rates. Their ability to acclimatize to VOCs ensures the system’s efficiency increases over time.
KEY FINDINGS FROM THE NRCC
The laboratory study conducted at the National Research Council of Canada employed a dynamic chamber test method, simulating real-time environmental conditions. This method provided a realistic evaluation of the Respira biofilter’s performance.
VOC Removal Efficiency: VOCs with low molecular weights and high dipole moments (high polarity) showed superior removal rates. Polar compounds, including formaldehyde, acetaldehyde, and acetone, exhibited higher removal rates (25-87%) while non-polar compounds like tetrachloroethylene and naphthalene had lower rates.
Microbial Adaptation: A significant observation was the evident adaptation of microbes. In tests where the same module was evaluated multiple times, higher VOC removal rates were observed in subsequent tests, highlighting the dynamic nature of the biofilter living wall system.
REAL-WORLD TESTING PARAMETERS
The dynamic chamber test method used in the study was designed to mimic real-world environmental conditions. This approach ensures that the findings are not just theoretically sound but also practically applicable. By simulating real-world conditions where multiple VOCs are present at once, the study offers insights into how biofilter living walls would perform in actual building environments, making the results more relevant for architects, building owners, and engineers.
Effects of Operating Parameters: The removal rates of pollutants in a biofilter are influenced by physical conditions, in addition to chemical properties. Factors such as the number of plant modules, chamber concentration, and chamber air flow rate played a role in VOC removal efficiency.
CONCLUSION
Biofilter living walls offer a comprehensive solution to modern building challenges. Their ability to improve indoor air quality, combined with the scientific principles governing their efficiency and the significance of real-world testing parameters, makes them invaluable for sustainable building designs. The findings from the National Research Council of Canada further underscore the potential of biofilter living walls in the architectural and environmental sectors.
