Product:
IBM Cognos Planning 10.1.1
Microsoft Windows 2008 R2 Server

Problem:
How change the TEMP variable for a service account, without logging in as the user on the Windows Server?

Solution:
Create the service account in the Domain.
Ensure the service account is part of the local administration group on the planning server.
Go to the Administration tools – services.
(you can start it by type services.msc in Run dialog)
Double Click on your IBM Cognos 10 Planning service and select Log On tab.
Select this account and browse to your service account, in our example named cogplan.
Enter Password and click OK to save the change.
Click OK on message that the account have been added to “log on as a service” function.
Right Click on the service IBM Cognos 10 Planning and select RESTART.
Ensure that Cognos planning service have started.

The planningerrorlog.csv file is created in folder \users\cogplan\appdata\local\temp

Start REGEDIT
Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
Check the last number in list – it is possible your service account.
You should see it on the ProfileImagePath value who would be : C:\Users\cogplan
Note the number if the user down
Go to HKEY_USERS\S-1-5-21-2298123480-4089459362-31738xxxxx-1001\Environment
(the number should be the number of the user you found under ProfileList.)
Double click on TEMP to change the value from
%USERPROFILE%\APPDATA\LOCAL\TEMP
to
D:\TEMP
Click OK
Repeat the change for TMP
Close REGEDIT

Restart the Cognos Planning service.

Now the log file is in the D:\TEMP folder.