The purpose of this study was to explore conditioning effects on wood panels (used as interior decorative materials). We examined hourly the temperature and relative humidity (RH) in a living environment based on the data of average values from 1974 to 1990 in the Taipei area. Thirty-six interior finish materials attached to one inside surface of a 353 cu cm simulation aluminum container were used in this study. An A/V ratio (surface area/volume) of 2.86 (m−1) or various other values and the panel thickness had no significant effect on the room temperature changing ratio. The hygroscopic conditioning performances of these decorative materials were classified into four types in accordance with b values: type I (b > 0.0200) included four solid woods (unfinished), seven wood-based materials, three composite materials, and one inorganic material. Type II (0.0170