The effects of an elongated building structure and skylight windows on wind-driven building ventilation

Natural building ventilation is an approach that does not rely on the application of mechanical devices. It is energy-efficient and environmentally friendly, thus very much preferred to other commonly used ventilation methods. The present experimental work focuses on the effects of the building elongation and skylight windows on the building air change rate (ACH), a topic not assessed before. In this framework, freestream flow velocity, flow incidence angle, and the opening angle of windows were studied as well. Experiments were performed in a boundary layer wind tunnel (BLWT) on a small-scale generic building model subjected to a scaled atmospheric boundary layer (ABL). Hot-wire anemometry was used for the flow velocity measurements, while a tracer gas technique was used for the ACH experiments. The results indicate that the cross-ventilation yields substantially higher ACH compared to the single-sided ventilation, where the ACH increases linearly with an increase in the skylight window opening. The shortest building model ( L = H, L is the building model length and H is the building model height) exhibited higher ACH than in the case of a cubic building model of the same dimensions, likely due to the window design and position. The ACH does not increase monotonically with the building elongation. The L = 2 H model exhibited slightly higher ACH than for the most elongated ( L = 3 H ) building model.