The programs and actions to rationalize energy consumption and increase energy efficiency, such as demand-side management (DSM) and demand response (DR), are receiving increasing attention. DSM involves the selection, planning, and implementation of measures intended to have an influence on the demand or customer-side of the electric meter. DR includes programs designed to encourage end-users to make short-term reductions in energy demand in response to price signals from the market or triggers initiated by electricity grid operators. This paper aims at studying DSM actions and DR programs to improve electricity efficiency in a public library (large building), taking into account a time of use (TOU) tariff. It presents a model of the library developed with the software DesignBuilder and using real data. It also proposes DSM actions to improve efficiency and reduce energy costs. Specifically, the analysis of the building equipment and their usage constraints lead to the development of load shifting and peak clipping mechanisms. Regarding DR programs, the library manager adopts a load direct control program proposed by a retailer and involving a reduction in consumption in the peak period of the day. The agents negotiate the terms and conditions of a bilateral contract, notably energy prices and contract duration. The DSM actions, the DR program and the negotiated rate allow the library manager to reduce consumption by 4% and lead to savings of about 7% in total annual costs.