This paper aims to describe and exemplify the developed concept of ‘designerly’ ways of simulation. Despite the relevance of architectural decisions on thermal and energy performance, the design support frequently relies on qualitative information, which sometimes can be inadequate to specific design situations. Simulation can enhance the quality of the design support, but its influence on architectural practice is still limited. Designerly ways of simulation should combine the power of analysis (from the tools) with the power of synthesis (from designers) to allow the solution of design dilemmas that can arise during the design process.