Effectiveness and Energy Saving Potential of Biofiltration of Indoor Air in U.S. Offices

Ventilation accounts for about 8-10% of energy consumed by commercial buildings in the U.S. Alternative strategies are being developed which can clean indoor air while simultaneously saving energy on ventilation. This work investigates biowalls as a ventilation alternative, and conducts Monte Carlo simulations to determine its effectiveness within the U.S. office stock as a means of cleaning the indoor air of VOCs and as a measure to save energy on ventilation. Savings were determined by comparing the ventilation energy required to maintain the same VOC concentrations for two indoor atmospheric box models: one incorporating a biowall and the other without. A sensitivity analysis was also conducted to determine the most influential parameters, and for a user to predict savings based upon known building parameters. It was found that the largest criterion for energy savings is climate. Median annual ventilation savings ranged from about 1 $/m2 in temperate locations such as San Francisco, to about 4 $/m2 in more extreme climates such as those found in Miami or Alaska. The median annual amount of energy saved on cooling in Miami was about 35 kWh/m2, about three times less than the 110 kWh/m2 of heating energy saved in Alaska; this difference caused by the nature of electric cooling versus gas-fired heating. This discrepancy is equilibrated when accounting for the cost of the respective utilities. While operating a biowall resulted in a net decrease in energy consumption in the majority of cases, operating cost increased significantly due to the projected cost of plant upkeep, which, with a median of about $3800/year, accounted for over half of the total biowall operational cost. Total biowall operating cost was not impacted by climate. It was instead highly variable but can be controlled by the design of the biowall itself and it building it occupies.M.S., Architectural Engineering -- Drexel University, 201