DOE-2 Reference Manual Version 2.1 - DOE2.com

system. Often, it is difficult to enV1Slon this angle,especially when the shading surface is horizontal, as shownin Figure 1I1.13. This confusion can normally be avoided bythe following procedure:1. Choose the ori gin of the shading surface.2. Mentally rotate the surface to a vertical position(keeping the origin in the same position and thatpos ition must be the lower left-hand corner as viewed ina direction oppos ite to the surface outward normal).3. Specify the angle between the building Y-axis and thesurface outward normal.4. Mentally rotate the surface back to horizontal andspecify TIL T=O.TIL Tis the angle between the positive Z axis of the buildingcoordinate system (vertical) and the surface outward normal.It is an angle between 0 degrees (horizontal) and 180 degrees(horizontal) with a default value of 90 degrees (vertical).Example:Note:This example places a shading surface near the building located by theexample in Sec. B of this chapter. The data entry below describes ahorizontal shading surface (l ike a carport) located parallel to and 10feet south of the building with its west edge aligned with the buildingwest side. The shading surface is 30 by 15 (long dimension is parallelto the building) and 10 feet above the ground (see Fig. II1.13).CARPORT = BUILDING-SHADEHEIGHT = 15.0WroTH = 30.0TRANSMITTANCE = 0.0X = 0.0Y = -25.0Z = 10.0AZIMUTH = 180.0TILT = 0.0Because X, Y, Z, AZIMUTH, and TILT of the shading surface are defined inthe building coordinate system, a rotation of the building (accomplishingby changing AZIMUTH in the BUILDING-LOCATION command) will carryallbuilding shading surfaces along with the building, even those which aredetached, such as adjacent buil dings and trees. Care must therefore betaken to adjust the X, Y, Z, AZIMUTH, and TILT of such detached shadingsurfaces each time the building is rotated, so that these surfaces stayfixed with respect to the global (earth) coordinate system.Also, allowing X, Y, Z, AZIMUTH, or TILT to default will almost alwaysproduce a surface with a incorrect orientation and thus incorrect shading.I I 1. 36 (Revised 5/81)