The Sustainable Energy Authority of Ireland (SEAI) (Irish: Údarás Fuinnimh Inmharthana na hÉireann) is an Irish governmental body established to promote and aid in the development of sustainable energy in Ireland.

It also funds and supports research into new technologies and their deployment in sectors including bioenergy, electric vehicles, the combination of heat and power systems, and ocean energy.

[3] The SEAI is the body overseeing Ireland's national retrofitting of domestic and business buildings to increase energy efficiency and the move away from fossil fuels as heat sources.

[4] The SEAI is engaged in supporting the offshore renewable energy sector in Ireland.

It does so by advising on government policy development, investing in grant schemes and the creation of test sites, and actively implementing the Irish Offshore Renewable Energy Development Plan (OREDP).