Sub test()
Dim i As Long, y As String
For i = 1 To 26
    Debug.Print Environ(i)
Next
y = Environ(15)
MsgBox y
End Sub

Environ arguments
ALLUSERSPROFILE
APPDATA
AVENGINE
CLIENTNAME
CommonProgramFiles
COMPUTERNAME
ComSpec
FP_NO_HOST_CHECK
HOMEDRIVE
HOMEPATH
INCLUDE
INOCULAN
LIB
LOGONSERVER
NUMBER_OF_PROCESSORS
OS
Path
PATHEXT
PROCESSOR_ARCHITECTURE
PROCESSOR_IDENTIFIER
PROCESSOR_LEVEL
PROCESSOR_REVISION
ProgramFiles
SESSIONNAME
SystemDrive
SystemRoot
TEMP
TMP
USERDOMAIN
USERNAME
USERPROFILE
VS71COMNTOOLS
WecVersionForRosebud.FF0
windir

Example :
msgbox Environ(“USERNAME”)