**1. Introduction**

The political target to cut energy use and greenhouse gas (GHG) emissions has various expressions. For example, the European Union some years ago set the target that energy efficiency must be improved by 20% by 2020. In good policy making, regional strategies must be parallel with national strategies. When the approaches in the national strategies are top-down, the regional approaches ought to be bottom-up. Therefore, the issue is to have policies that work in practice or "in the real world" (Johansson, 2006).

The policies whether they are carried out in a company, or at a regional, a national or even continent-wide level need tools. Industry is diversifying all the time. Does this development path mean that industrial energy use is diversifying as well? At first glance when going very deeply into energy use this seems to be true. The energy use may be diversified when looking at the details, but to conduct an energy-efficiency policy or GHG emission reduction policy with a wide scope requires generalisations. This is certainly the case when we withdraw from the detailed level. The energy use must be categorised. This article will mainly discuss these tools and how to generalise and categorize industrial energy use.
