The following three environment variables are set by iisexpress.exe during the process startup.
%IIS_BIN%– refers to IIS Express installation folder (%PROGRAMFILES%\IIS Express)%IIS_USER_HOME%–%USERPROFILE%\Documents\IISExpress%IIS_SITES_HOME%–%USERPROFILE%\Documents\My Web Sites
%SYSTEMDRIVE% – is a standard windows system environment variable