Covers design wind loads for buildings and the role of boundary layer wind tunnel (BLWT) testing in the determination of such loads. It explains how design wind loads on curtain walls should be determined and provides information sufficient for an understanding of the boundary layer wind tunnel and its unique features, how it is used to develop wind load data essential to safe and efficient wall design, when its use should be considered, and why good climatological data is critical to the effective use of the tunnel.