Time zone (select and offset)

How to use ‘time_zone_select’ and get the returned value as offset, not
a string. 0 instead of ‘London’, 1 instead of Brussels, and -1 instead
of azores.

I have tried using my own hash with ‘select’. But hashes are not sorted
so the output is a mess.

If it’s not possible to get offset for ‘time_zone_select’, is there any
way to sort hashes?