This thesis examines the possibilities and limitations of connectingoffice buildings to demand response (DR) programs, with emphasis on the effect it has on indoor climate. Heating, ventilation and airconditioning (AC) systems was used as sources to scale power, and thereby contribute with power to capacity markets related to the electrical grid. By simulations performed in MatLab, as well as livetests in one of Vasakronan’s buildings, this work contributes with knowledge of DR in office buildings in the Swedish environment, which to date have been lacking in literature. All systems considered in thisreport has potential to contribute with power to DR programs. Heating and AC systems has greater power saving potential than the ventilation system. However, ventilation also holds potential as a source of power savings and is applicable to a larger portion of the building stock.Indoor air carbon dioxide level is affected to varying degrees depending on the extent of power reduction, where a reduction up to 90 % of ventilation is possible without exceeding approved limits. Reduction of ventilation caused the highest rise in carbon dioxide levels during mid- day and especially during the winter. Flexibility is key for the control system, especially when considering future climate challenges andtrends. DR strategies should include control of all systems both during the active DR time but also when returning to normal activity to reduce the risk of compensation from other systems.