In recent years, there has been a risen interest in retrofit in heritage buildings, especially energy and comfort retrofitting. Global governments pay much more attention on the preservation and reuse of heritage buildings. However, the retrofit might alter appearance of heritage building. In this paper, the investigation on a novel thermoelectric ventilator retrofit in heritage buildings has been undertaken. Firstly, an AHP methods-based survey has been conducted to identify appropriate component to apply the ventilator with minimum impact on the heritage features. Secondly, an overview of the prototype design, heat transfer model and experimental parameters would be presented. Finally, the MATLAB model along with Revit has been used to simulate the prototype’s performance when installed in a sustainable house in the UK. According to the result, the prototype would supply 655 kWh heating energy for year-round operation and enhance the air change rate of the heritage buildings. This research would provide a new solution to reduce energy consumption during daily ventilation in heritage buildings.