The study aims to develop a simplified calculation method to simulate the performance of double glazing fac¸ ade with night insulation. This paper describes the method to calculate the thermal properties (Uvalue) and comfort performance (internal surface temperature of glazing) of the double glazing facade with the night insulation. The calculation result of the internal glazing surface temperature has been validated with experimental data collected in a full-scale fac¸ ade element test facility at Aalborg University (DK). With the help of the simplified method, dynamic U-value of the facade with night insulation is calculated and compared with that of the facade without the night insulation. Based on standards EN 410 and EN 673, the method takes the thermal mass of glazing and the infiltration between the insulation layer and glazing into account. Furthermore it is capable of implementing whole year calculation at different time steps. Acceptable accuracy and simplicity inputs are also the advantages of the method, which make it a suitable tool to evaluate the performance of night insulation during the design stage of buildings. The result calculated by the method proves that the facade with the night insulation performs much better than that without the night insulation.