This article analyses the tensions between democracy and expertise in the context of contemporary climate and energy policies, and focuses on the role of scientific models in the production and management of those tensions. In doing so, the article develops a markedly interdisciplinary approach by combining concepts and tools coming from political philosophy, philosophy of science and science and technology studies. The first section introduces some of the main interconnections between democratic regimes, expert knowledge and energy systems. The second section explores the role of scientific modelling in current climate science and energy policy debates, also highlighting the epistemic and political challenges raised by both climate models and Integrated Assessment Models-the most widely-used models in the energy field. The third section proposes an interdisciplinary critique of the recourse to IAMs as policy-making tools, bringing together studies of model performativity and epistemic ideology critique.