Paramiko/Open SSH get env variable paths

When I connect to a windows machine running OpenSSH with paramiko i can't seem to get paths by using the enviroment variable. For instance:

>>stdin, stdout, stderr = _ssh.exec_command('cd %PYTHON_HOME%')
>>print(stderr.read())
>>b'The system cannot find the path specified.\r\n'

>>stdin, stdout, stderr = _ssh.exec_command('cd %SYSTEM%')
>>print(stderr.read())
>>b'The system cannot find the path specified.\r\n'

Any ideas? I know the absolute path of those folders on the server, but I'd rather use env variables as that is the whole point of env variables, to let the target machine determine the location of its own resources.