Measurements of the performance of a wind-driven ventilation terminal

This paper presents the results of the measured ventilation flow rates through a roof-mounted inflow/outflow natural ventilator and of the wind pressures measured on the terminal under real conditions. The experiments were conducted at full scale at the former Silsoe Research Institute wind engineering test site using a 6 m cubic test building, referred to as the Silsoe cube, and using a test house. Ventilation rates and free-stream wind speed were measured using ultrasonic anemometers. The nominally 800 mm 3 800 mm ventilation terminal on the Silsoe cube achieved a peak ventilation rate of 0.06 m(3)/s per m/s wind speed although the data also indicated periods when the ventilation rate dropped to approximately zero for a specific wind direction due to the vent then being in the position of flow re-attachment following separation at the windward leading edge of the roof. This has led to better knowledge in relation to the siting of such terminals. A similar terminal monitored on the test house achieved a peak ventilation rate of nearly 0.1 m(3)/s per m/s wind speed. The ventilation unit proved to be an effective means of providing natural ventilation and is likely to broaden the application of natural ventilation. The results of pressure measurements on the terminal louvres and the internal pressure in the cube, coupled with the measurements of the corresponding ventilating flow rate mechanisms, provide unique data with which to establish procedures for the rational design of such terminals, which is also outlined in the paper.