The awareness for software as an important player regarding the energy consumption caused by ICT steadily increased in the past years. The impact of software on the energy consumption is also more and more accepted by the research community under the umbrella of sustainability in general. Nevertheless, the end user is still only slightly or not addressed in the research activities regarding the whole energy consumption of software over its complete lifecycle. Also other stakeholders, e.g. administrators, designers, developers etc., are not in the focus of creating awareness for the aforementioned topics. In this contribution, we therefore focus on ideas, approaches, and challenges in developing a general-purpose labelling process for green and sustainable software products and websites. At first we provide a literature roundup, followed by the elaboration of requirements for the creation of a sustainability label for software products in general based on already existing and new approaches. On a first attempt, we furthermore concentrate on a labelling process for sustainable as well as green websites and sum up with a discussion followed by an outlook on our future work.