Experimental Investigation of Natural Ventilation Rates in a Domestic House in Laboratory Conditions

Stack-driven ventilation is one of the key forms of natural ventilation. Yet, it has rarely been tested at full scale, even though such studies offer critical evidence for validating simplified theoretical models. To investigate stack-driven ventilation experimentally, a full-scale Future Home house was tested under controlled laboratory conditions in an environmental chamber at Energy House 2.0, in the absence of wind and with a stable indoor–outdoor temperature difference. The indoor air was heated to 35 °C, while the surrounding chamber was maintained at 15 °C. Subsequently, six windows were opened simultaneously for 24 h, three on the ground floor and three on the first floor. Air velocities were measured at each opening with hot-wire probes and converted into volumetric flow rates. The total inflow averaged 1.19 m3/s compared with a theoretical prediction of 1.93 m3/s, indicating systematic overestimation by the stack effect equation. A back-calculation suggested a discharge coefficient of 0.37 instead of 0.60. The cooling energy from natural ventilation was quantified and evaluated for its capability to reduce internal air temperature in overheating conditions. The findings increase the understanding of buoyancy-driven ventilation, while underlining the need to calibrate simplified equations against experimental data.