Environmental evaluation of wood-based remodeling in aging buildings focusing on indoor air quality and life-cycle carbon emissions.

The application of wood-based interior finishes in building remodeling is increasing; however, empirical evidence regarding their impacts on indoor air quality (IAQ) under real-world conditions remains limited. This study evaluates IAQ changes before and after wood-based remodeling through mock-up testing and field measurements conducted in two contrasting buildings: an occupied childcare facility (SB1) and an unoccupied university classroom (SB2). Mock-up experiments characterized baseline emissions from softwood materials, identifying monoterpene hydrocarbons particularly α-pinene as the dominant biogenic volatile organic compounds (BVOCs), while oxygenated monoterpenes were detected only at trace levels. Field monitoring was performed before remodeling, 24 h after remodeling, and after four weeks, measuring formaldehyde (HCHO), anthropogenic volatile organic compounds (AVOCs), BVOCs, particulate matter (PM), and total airborne bacteria (TAB). In SB1, TAB and PM concentrations decreased or stabilized over time, and most VOCs showed significant reductions within four weeks, reflecting continuous ventilation and occupant activity. In contrast, SB2 exhibited substantial BVOC accumulation, with α-pinene increasing from 28.7 μg/m3 before remodeling to 1713.6 μg/m3 after four weeks due to limited ventilation. A life-cycle-based global warming potential (GWP) assessment further showed that although wood had comparable absolute GWP to gypsum board and paint, biogenic carbon storage significantly reduced net emissions. In SB2, net GWP decreased to 37.7 kgCO2eq, approximately 9-11 times lower than non-wood materials. These findings demonstrate that wood-based remodeling can maintain acceptable IAQ under proper ventilation while providing substantial carbon mitigation benefits toward building-level carbon neutrality.