This paper presents the application of passive ventilation system with crawl space heating to the practical house. Ventilation rates, in door thermal conditions and heat loss with ventilation were measured and discussed. The results are as follows; 1) Proper ventilation rate realized during whole year except mid summer, just by operating the number of exhaust stacks, such as one for the heating period and two for the other season. 2) Estimated heat loss with ventilation was 10 % larger in the measured ventilation rate than that in the constant 0.5 ach. The difference was corresponds to the difference of ventilation rate. As a result, airflow fluctuation did not increase the heat loss. 3) Floor surface temperature in the living space was 1-2℃ higher than in door air temperature by crawl space heating. Therefor, in door thermal comfort of this system was similar to low-temperature radiant heating system like a floor heating.