As the important components of buildings, windows not only provide ventilation and daylight but also lead to significant energy loss and gain through temperature differentials and solar radiation. Therefore energy efficient building requires energy efficient window design. A novel vacuum window system can significantly improve thermal resistance as well as reduce the condensation problem and energy losses. The windows comprised by evacuated panels which can achieve a high performance window technology with a U-value less than 0.7 W/m2.K. The development of energy efficient window technology would be compatible with the higher levels of the Code for Sustainable Homes and contribute to the future requirements of commercial buildings. This paper represents prototype description of novel window system as well as mathematical analyses of the energy transfer process through a setup of computer programme, compared computational modelling results to the monitoring data of prototype window, consequently to assess the performance of the proposed window system.