An integrated model capable of predicting the emission/sorption of VOCs from/on building materials under the variable air exchange rate has been developed. The semi-analytical solution is presented by using generalized integral transform technique (GITT). The present semi-analytical solution can apply to the cases of ventilation and no ventilation without modification to the coefficients of the semi-analytical solution based on N = 0 or not. A self-adaption to N = 0 can be realized automatically. Four typical physical processes were adopted to validate the present model: VOCs emission/sorption in ventilated chamber and VOCs emission/sorption in airtight chamber. Good agreements between the computed concentration and the experimental data are obtained. The effect of variable air exchange rate on the concentration in the air is studied in detail. The present model can be used to predict the concentration under the variable air exchange rate. (C) 2013 Elsevier Ltd. All rights reserved.