Influence of sorption area ratio and test method on formaldehyde reduction performance for sorptive building materials

• Reduction tests were conducted with changes in sorption area ratios.
• CCSM always showed higher performance values than EMM in sorption flux Fs.
• The smaller sorption area ratio brought more advantages to the Fs values.
• HBF compensation narrowed the disparities between EMM and CCSM in Fs.
• Fs values were determined depending on the ratios of sorption area.

Sorptive materials can be used to improve the air quality by adsorbing harmful chemicals and other pollutants in indoor air. This study aims to (1) investigate the differences in the reduction performance values with changes in surface area ratios of sorptive materials for the two test methods (constant concentration supplying method and emission material method, hereinafter CCSM and EMM); (2) discuss whether the sorption flux “Fs” and equivalent ventilation rate “Qeq”, which are two ways of representing the results, can accurately represent the reduction performance; and (3) suggest a method for compensating for disparities between the two test methods.Under the standard sorption area condition, CCSM yielded Fs with higher performance than EMM. The evaluation using Fs gave more advantage to a smaller sorption area condition, and CCSM was less influenced by the area than EMM. Changes in the area ratios resulted in changes in Fs, but Qeq was less affected. However, for an identical area ratio condition, Fs resulted in steady values, while Qeq fluctuated owing to subtle changes in chamber concentrations. Compensation using the HBF (Hoetjer–Berge–Fujii) equation could improve EMM performance value and thus reduce the disparity between the two methods.