Ines,
I would be surprised if you need to change CONTAM files
mid-simulation. If you are using the Type98 coupling then you should be
able to control the opening factor for the various airflow paths through
additional inputs to the Type98 model. You can do the same with the
Type97 coupling (i.e. define controllable openings). Instructions for
doing so can be found in the Type97 section of the
04-MathematicalReference manual.

It is possible to select different building files for a parametric
run but in order to do so, you need to edit the *.dck manually and add
some lines. The basic steps are as follows:
1. make sure that all of your building files have exactly the same
inputs and outputs.
2. open the *.dck in TRNEdit and find the line that assigns the *.b17
file an integer value. It should look something like: ASSIGN
"MyBuilding_v1.b17" 31
3. copy that line and paste it as many times as you have different
versions of the *.b17. Change the name of the *.b17 file each time and
choose a unique integer each time. You might end up with:

ASSIGN "MyBuilding_v1.b17" 31
ASSIGN "MyBuilding_v2.b17" 32
ASSIGN "MyBuilding_v.3b17" 33
ASSIGN "MyBuilding_v.4b17" 34

NOTE: it is very important that you search through the *.dck and make
sure that there are no other ASSIGN statements that refer to the same
integers that you've chosen. You can choose any integer between 11 and
999. Make certain they're unique or else you'll get a fatal error when
you run the simulation.

4. Find the definition of Type56, specifically the definition of
Type56's first parameter. It might look like:

...
PARAMETERS 3
31 ! 1 Logical unit for building description file (.bui)
...

change it to look like:

...
PARAMETERS 3
BLDG_LU ! 1 Logical unit for building description file (.bui)
...

5. add the following lines to the *.dck

CONSTANTS 1
BLDG_LU = 31

6. Choose "new table" from the "Parametrics" menu and select the BLDG_LU
variable. Enter the values of the integers you chose in step 3 in each
row of the parametric table.

kind regards,
David