Lopes, Rui AmaralSilva, FranciscoMenezes-Barros, RafaelAmaro, NunoCarvalho, Ana Gonçalves deMartins, João2025-07-162025-07-162025-02-010360-5442PURE: 106860686PURE UUID: 34772824-5818-4d8f-b1ff-7b5fce36f543ORCID: /0000-0002-6953-1403/work/175015300WOS: 001399705700001Scopus: 85214803474ORCID: /0000-0001-5781-7482/work/188080139http://hdl.handle.net/10362/185229Funding Information: This research was partly funded by European Union's H2020 programme as part of the IANOS (Integrated Solutions for Decarbonization and Intelligence of Islands) project, Grant Agreement ID 957810), and by the Portuguese “Fundação para a Ciência e a Tecnologia” (FCT) in the context of the Center of Technology and Systems CTS/UNINOVA/FCT/NOVA, reference UIDB/00066/2020. Authors also would like to acknowledge IEA EBC Annex 82 (Energy Flexible Buildings Towards Resilient Low Carbon Energy Systems).The integration of renewable energy sources, which often have limited dispatchability, along with the rising electrification of energy demand, is increasing the complexity of managing power systems. To address this challenge, smart solutions that leverage energy flexibility in buildings can support power system operations by adapting energy consumption according to existing needs. This study presents a forecasting and IoT-based solution for electric water heaters designed to improve energy flexibility, lower electricity costs, and enhance self-consumption of locally generated energy. Deployed in a real-world setting on Terceira Island, Portugal, the solution successfully replaced a gas boiler, achieving a 56 % decrease in electricity costs and a 34 % reduction in CO2 emissions (compared to a scenario with a 75 % efficiency gas boiler). These benefits were realized while maintaining acceptable levels of comfort and user engagement.1712819978engSmart electric water heaterInternet-of-ThingsForecastingEnergy flexibilityElectrificationCivil and Structural EngineeringModelling and SimulationRenewable Energy, Sustainability and the EnvironmentBuilding and ConstructionFuel TechnologyEnergy Engineering and Power TechnologyPollutionMechanical EngineeringGeneral EnergyManagement, Monitoring, Policy and LawIndustrial and Manufacturing EngineeringElectrical and Electronic EngineeringSDG 7 - Affordable and Clean Energyjournal article10.1016/j.energy.2025.134381https://www.scopus.com/pages/publications/85214803474https://www.webofscience.com/wos/woscc/full-record/WOS:001399705700001