Energy demand reduction is critical to comply to the Paris Agreement climate policy ambition, downsizing not only direct emissions but also the upstream supply emissions. Such a transition will depend on changed consumer behaviour. Integrated assessment models, widely used to analyse long-term mitigation pathways, tend to focus on supply side solutions. The rules affecting behavioral change are less defined, than the “rational” cost-optimization that are typically used in the supply sectors. We argue that in fact the models do include behavioural mechanisms, but that they are often implicit and not communicated in a transparent way. To understand the role of behavioral change in these long-term pathways, the first step is to unpack these embedded behavioral assumptions, which could morevover provide insights in to the large, across model, demand sector emission ranges. While numerous efforts have been performed to improve transparency on the supply side, this has to date not happened for behavior affecting demand. This perspective takes a first step by discussing key behavioral model assumptions along four dimensions: mechnisms, durability, actor and scope. We emphasize that the evaluation of those behaviors that are impactful, have a society wide effect and can be affected by policy levers, should be prioritzed.