DESIGN AND WIND TUNNEL PERFORMANCE TESTING OF A NEW OMNI-DIRECTIONAL ROOF VENT E. Grant, J. Jones and P. Vlachos 1 Abstract: Low-slope roofs are subjected to potentially high levels of suction pressure. Traditional methods of attaching roof membranes to substrates are prone to failure when the low pressure on the roof surface instigates a transfer of forces to the roof membrane. Existing pressure-equalized roof systems use the power of the wind to transmit low pressure to the space immediately beneath the roof membrane, pulling the membrane down to the roof surface. The object of this study is the design of a wind vent which, when coupled with a single-ply roof membrane in a complete roof assembly, will successfully equalize low pressure throughout the entire field of the roof. The proposed wind vent differs from existing equalizer valves in its use of the Bernoulli effect to create low pressure. Optimized for ease of manufacturing and installation, the vent is omni-directional and contains no moving parts. After the wind vent prototype is developed, future study will be required to determine the tributary area of each vent and other roof system parameters. Introduction The following describes the design and wind tunnel performance testing of a new omni-directional roof vent for membrane roof systems. The new vent is designed to take advantage of fluid mechanics and aerodynamics principles to eliminate the uplifting pressures that develop on membrane roofs during high wind conditions. The new vent design is based on two elements, one mounted above the other. The convex curvature of the upper and lower elements are designed to induce a Venturi effect which, by smoothly constricting the airflow as it passes between the base and upper element, creates a low pressure zone inside the vent base relative to the ambient free-stream pressure. This low pressure zone draws the membrane down onto the roof deck, thus preventing uplift and possible detachment of the membrane layer. The vent is designed to be omni-directional, functioning efficiently with any wind direction. The vent is unique and differs from other commercially available roof vents in that: 1) It takes advantage of airflow principles such 1 E. Grant is a doctoral student in the EDP program, J. Jones is an Associate Professor in the College of Architecture and Urban Studies and P. Vlachos is an Assistant Professor in the College of Engineering at Virginia Tech.