Connaitre le fuseau horaire

function GetTimeZone:String;
var
TimeZone:TTimeZoneInformation;

begin
GetTimeZoneInformation(TimeZone);
Result:='GMT '+inttostr(TimeZone.Bias div -60);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
Label1.Caption:=GetTimeZone;
end;