This paper presents the results of full-scale experiments in a realistic building to evaluate natural convective heat and mass transfer through doorway-like apertures under small temperature differentials. The zone-to-zone temperature differences were nominally between re and 2.5°C. Heat transfer correlations, coefficient of discharge, and thermal stratification are reported for air (Pr = 0. 71), an enclosure aspect ratio of 0.26, aperture height relative to the enclosure height in the range of 0. 75 to l, and aperture width relative to the enclosure width in the range 0.29 to 0. 79. In general, the results extends the validity of previous theoretical and experimental work in the literature to large doorway-like apertures and small temperature differentials across the aperture typical of residential building conditions.