Thermodynamic Analysis of the Effect of Temperature on VOCs Emission from Building Materials

This study attempts to interpret the physical mechanism of temperature affecting the emission of VOCs from building materials from the viewpoint of thermodynamics. VOCs adsorbed onto building materials are assumed to form a condensed thermodynamic system. The kinetic energy of VOCs molecules takes values from zero to infinite. It is assumed that only VOCs molecules with a kinetic energy greater than the critical value can escape from building materials. Based on the Maxwell velocity distribution function, the correlation between the initial concentration of VOCs within building materials and temperature is derived. By use of the Laplace transform technique and the theorem of the initial value, the correlation between the initial emission factor and temperature is further presented on the basis of the diffusion mechanism. The present thermodynamic model was validated through experimental data in the literature. A good agreement between the present thermodynamic model and experimental data is obtained. The present thermodynamic model can also explain the effect of temperature on the emission of other gases from materials.