Demand-side management (DSM) seeks to reduce overall energy consumption or change when energy is used to reduce peak demands and smooth the load curve. DSM is increasingly moving to the forefront of the energy policy agenda in many countries due to objectives for energy security, affordability and carbon emissions reduction. However, the policy side of DSM has been little explored in the literature, and the paper proposes how the method of systematic reviews can be applied to the energy policy field. Systematic reviews are commonly used in the medical sciences and are beginning to be applied to social science disciplines. The realist synthesis approach is utilised to determine not only impacts, but to analyse how and why policies are successful, and how contextual factors, such as market structure and regulatory environment, influence their success. A study quality assessment scale is proposed to appraise the quality of studies in determining what documents are included in the review. Systematic reviews are an effective method for collating the results of all the previous studies that have been done on a given programme, and it has an important and useful role for improving the evidence base for informing energy policy. The paper focuses on evaluating the method, discusses the case for realist synthesis to overcome issues of establishing how and why DSM policies work or fail and gives an example from ongoing research into how it can be applied to analyse DSM policy.