DOE-2 Reference Manual Version 2.1 - DOE2.com

of the space coordinate system is defined relative to the origin of thebuilding coordinate system, and the surface coordinate system is locatedrelative to the origin of the space coordinate system. There is only onebuilding coordinate system, but there is one space coordinate system foreach space defined by the user, and one surface coordinate system for eachexterior wall or roof defined by the user. The user need not keep trackof the overall position of each surface and window/door relative to thebuilding as a whole. Instead, the position of walls and roofs is specifiedrelative to the space in which they occur, and the positions ofwindows and doors are specified relative to the wall on which they occur.The program then automatically transforms the walls and windows to theoverall building coordinate system.The building coordinate system is defined in the BUILDING-LOCATIONinstruction by assigning values to the keywords AZIMUTH, LATITUDE,LONGITUDE, and ALTITUDE. A space and its coordinate system are locatedwithin the building coordinate system by aSSigning values to the keywordsX, Y, Z, and AZIMUTH in tne SPACE instruction. The wall or roof islocated within the space coordinate system by giving values to the keywordsX, Y, Z, AZIMUTH, and TILT in the EXTERIOR-WALL (or ROOF) instruction.Each exterior wall or roof has a surface coordinate systemassociated with it. Windows are located relative to a surface coordinatesystem by assigned values to X, Y, and SETBACK in the WINDOW instruction.BUILDING-SHADEs form a speCial class of surfaces in that, unlike exteriorwalls or roofs, they must be located in the building coordinate system.If the user does not use the BUILDING-SHADE instruction, there is no needto keep track of the location (X, Y, and Z keywords) of spaces, walls, andwindows. All that is needed is that the orientation (AZIMUTH and TILT) ofthe walls be correctly specified. The user can allow the X, Y, and Zkeywords to default to zero.a. Building Coordinate SystemSPACEs and BUILDING-SHADEs are specified relative to the buildingcoordinate system. The coordinate system is defined in theBUILDING-LOCATION instruction. The location of the origin is fixedby values assigned to the keywords LATITUDE, LONGITUDE, and ALTITUDE.The orientation of the coordinate system is such that the z-axis isvertical and the x-y plane horizontal (right-hand Cartesian coordinatesystem). The user may rotate the coordinate system about the z-axisby using the AZIMUTH keyword. The AZIMUTH is defined as the clockwiseangle between true north and the building y-axis. Thus AZIMUTH = 0means that the y-axis points north, AZIMUTH = 90 means that the y-axispoints east, and so forth.It is recommended that, for a simple rectangular building, the userorient the building coordinate system so that the x-axis runs alongthe front of the building, and the origin is located at the lowerleft-hand corner of the front wall, as viewed from the outside (seeFig. 111.2). For more complicated building shapes, any convenientlocation of the origin and orientation of the AZIMUTH may be chosen.111.8 (Revised 5/81)