A Sustainable Energy Action Plan (SEAP) is a document that outlines a municipality's strategy for achieving its energy efficiency and renewable energy goals. The SEAP is a key component of the Covenant of Mayors, an EU initiative that aims to promote sustainable energy in municipalities. SEAPs have evolved to Sustainable Energy and Climate Action Plans (SECAPs) which includes a wider scope, covering not only energy efficiency and renewable energy goals but also climate change mitigation and adaptation actions.

SEAPs/SECAPs typically include a baseline emissions inventory, energy consumption and production forecasts, and a set of actions and measures aimed at achieving the municipality's energy and climate goals. The measures are often divided into different sectors, such as buildings, transportation, and industry, and can include a combination of energy efficiency measures, renewable energy projects, and awareness-raising activities.

It's important to note that the development and submission of a SECAP is often a precondition to access some particular European grant funding, like under the European Regional Development Fund or the European Structural and Investment Funds, for the implementation of the plans' actions and measures.

The history of SEAPs dates back to the Covenant of Mayors initiative, which was launched in 2008 by the European Commission and the Committee of the Regions. The initiative aimed to promote sustainable energy in municipalities and to encourage cities to voluntarily commit to reducing their greenhouse gas emissions by at least 20% by 2020. As part of the Covenant, municipalities were required to develop a SEAP that outlined their strategy for achieving their energy and climate goals.