Research on dynamic operation of active botanical biofilters for indoor air purification: Multi-objective analysis and optimization

• Evaluated active botanical biofilter via efficiency, energy, economic, environmental. • Quantified the dynamic impact of operational variables on key performance indicators. • Implemented a digital-twin, time-resolved life cycle assessment. • Optimized use-phase parameters for various environmental conditions. • Developed functional unit-based and energy metrics across operating set-points. Active botanical biofilters (ABBs) are potential solutions for low-energy indoor air purification; nevertheless, their dynamic performance and life-cycle implications under operational settings are inadequately investigated. This study develops and experimentally validates a 4E (Efficiency, Energy, Economic, Environmental) framework, coupled with a digital-twin–enabled, time-resolved life-cycle assessment (DT-LCA), to evaluate a portable ABB treating formaldehyde under dynamic indoor loads. A three-species planting and a multi-component porous substrate were tested at four airflow set-points (62–94 m³ h⁻¹) and four inlet concentrations (0.05–1.00 mg m⁻³) in 60-min dynamic trials. Key performance indicators included single-pass removal efficiency (SPRE), elimination capacity (EC), clean air delivery rate (CADR), pressure drop (ΔP), quality factor (Q F ), and energy efficiency ratio (EER), normalized to two functional units: FU-1 (1 m³ of clean air) and FU-2 (one operational year at 8 h day⁻¹, 300 days yr⁻¹). Across all scenarios, SPRE ranged from 33.4 to 94.0 %, EC between 1.60 and 50.37 mg h⁻¹, with CADR between 31.4 and 64.6 m³ h⁻¹. Q F spanned 0.36–2.38 mmH₂O⁻¹, while EER varied from 0.20 to 0.89 m³ W⁻¹ h⁻¹, peaking at the lowest fan setting and declining monotonically with increasing power. DT-LCA results show that use-phase electricity dominates life-cycle burdens and identify moderate-to-low airflow regimes as the operating region that maximizes Q F and EER. These findings support the use of ABBs as energy-aware IAQ control elements via the integrated 4E/DT-LCA framework, providing actionable guidance for the design, control, and HVAC integration of next-generation ABB systems.