The position of the stack on the roof must be entered by the user for this non-regulatory option. A
ratio based on the distance of the stack to the centerline of the building perpendicular to the wind
flow for each of the two orientations is calculated by Screen View. If the ratio calculated by the
interface is more than 0.5, it will be adjusted by the SCREEN3 model to 0.5. Ratios greater than
0.5 indicate that the stack is not on the roof. The diagrams on the next page show how the ratios
are calculated. The description of the Schulman-Scire Algorithm can be found in the Section
3.9.3 of the SCREEN3 Model User's Guide