Although an insulation performance of a house is improving with rise of an environmental awareness, thermal performance of window frames is still low. The poor performance occur problems such as heat bridge or condensation. Then we propose to apply a dynamic insulation system to window frames. In previous study, we have done some feasibility studies using computer simulations. The results show that the system can decrease the heat loss to almost zero. In this study, we checked its performance using its prototype installed into an experimental house. The experimental house is located in Sapporo, Hokkaido. Through a measurement in winter, we prove that the system works even in cold climate. With a usual ventilation amount for a person, the outdoor surface temperature of the window frame becomes almost same as outdoor environmental temperature. It means the heat loss from window frame surface to outdoor is almost zero.