Model Change Bulletin

                                     MCB#4

                              BPIP (dated 95086)

     This is a formal notification of changes made to the Building Profile
Input Program (BPIP) source code.  The changes result from a reported
problem with the roof stack algorithm.  The changes are discussed first and are then
then followed by a list of changes made to the source code.  The model is
available for downloading under the Related Programs menu of the Air Quality
Models area of SCRAM BBS.

     Six pages to the user's guide were revised and discussed in the previous
Model Change Bulletin.  These pages are available in the current ZIP package,
BPIP.ZIP, for replacement of original pages in the BPIP user's guide.

DISCUSSION OF SOURCE CODE CHANGES

     A problem was found with the automated roof stack algorithm when tier
corners are entered in a counterclockwise direction.  Some of the roof stacks
under certain conditions are not detected as being on a particular roof.  An
absolute (ABS) function was added to a line of code that corrects this problem.

SOURCE CODE CHANGES

     The following is a list of changes made to BPIP:

1.   The SCRAM header and format line have been changed to reflect the
     new BPIP version date.  The header lines have been changed from:

C  *              BUILDING PROFILE INPUT PROGRAM (DATED 95039)              *
C  *                                                                        *
C  *              *** SEE BPIP MODEL CHANGE BULLETIN MCB#3 ***              *

to:

C  *              BUILDING PROFILE INPUT PROGRAM (DATED 95086)              *
C  *                                                                        *
C  *              *** SEE BPIP MODEL CHANGE BULLETIN MCB#4 ***              *


and the format line has been changed from:

461   FORMAT(30X,'BPIP (Dated: 95039)')

to:

461   FORMAT(30X,'BPIP (Dated: 95086)')

2.   The following modification comment has been added:

C                       March 27, 1995 - To fix a problem with the roof stack
C                                        algorithm when tier coordinates are
C                                        entered in a counterclock-wise
C                                        direction.  Some stacks were not
C                                        detected as being on a roof.

3.   An additional absolute (ABS) function was added to the following line of
     code so tier corners, when entered in a counterclockwise direction,
     would be properly identified as being or not being on a roof.
     The line of code was changed from:


              IF (ABS(360. - DIRTT) .LT. 0.02) THEN

to:

              IF (ABS(360. - ABS(DIRTT)) .LT. 0.02) THEN