We evaluate the possibility to reduce congestion in the transmission grid through large-scale implementation of demand-side management (DSM) in the form of load shifting for the EU-27 countries, Norway, and Switzerland for Year 2020. A linear, cost-minimising, dispatch model that includes a DC load-flow description of the transmission system and a general representation of load shifting is used. It is assumed that the EU Member States fulfil the targets for Year 2020 in their national renewable energy action plans. In the model calculations, a reference case without load shifting is compared with cases in which the load shifting is 5%, 10%, 15% or 20% of the load. The possibility to shift load in time is added exogenously and economic incentives for DSM are not evaluated. Three types of congestion are identified: peak-load-hour congestion, low-load-hour congestion and all-hour congestion. Peak-load-hour congestion is reduced as the DSM share of the load increases, whereas low-load-hour congestion, which is typically associated with a high level of wind generation, persists at all the DSM penetration levels investigated. We show that all-hour congestion occurs between systems that have large differences in supply structure, and that the impact of DSM on all-hour congestion is low. (C) 2014 Elsevier Ltd. All rights reserved.