Thermal insulation plays an important role in building energy savings. Previous researchers mainly focused on the exterior building envelope insulation. However, interior building envelope insulation can also reduce the building energy consumptions by minimizing the heat transfers between adjacent zones at different temperatures, especially for the multi-zone buildings. In this research, we studied the thermal insulation performance of the glass fiber board used for interior building envelope. Firstly, a mathematical model was developed to predict the effective thermal conductivity of the glass fiber boards. Then the mathematical model was validated by the measured thermal conductivities of four sample glass fiber boards with different thicknesses. Finally, we used eQuest to simulate the heating energy consumptions of a typical residential building using central heating system and the glass fiber boards as the interior building envelope insulation. The simulations were conducted in two different climatic zones in the northern China. The simulated results indicated that there was considerable heating energy saving potential by using the glass fiber boards as the interior building envelope insulation. Nevertheless, the glass fiber boards were not suggested to be too thick, for the energy saving percentages increased slowly when the insulation thickness was above 20 mm. (C) 2015 Elsevier B.V. All rights reserved.