How to only show entries older than 12 months I want to build an archive template where only entries older than 12 months show up.
Is there an clean and easy way to do so? I only have strange calculations in mind.
Something like this would be nice :)

{% for entry in craft.entries.section('news') if entry.postDate &gt; 12monthsago %}
{% endfor %}
You were close, you can set a postDate param on your craft.entries criteria model. And the Twig filter date_modify helps you to get the DateTime from 12 months ago.

{% set timeAgo = now|date_modify('5:00 -12 months') %}
{% set postDateParam = '&lt; ' ~ timeAgo|date('U') %}

{% set entries = craft.entries.section('news').postDate(postDateParam) %}