Reducing energy consumption for space conditioning of buildings is pivotal to pursue a sustainable growth and to flight climate change. Using efficient and renewable energy systems is therefore necessary. As concerns space heating, such systems operate with lower temperatures (in the range 40 - 55 °C) compared to traditional ones (e.g., gas boilers). Thus, coupling them with typical radiators − i.e., the most popular heating terminals of residential buildings – is not the best choice, given that radiators have to operate at higher temperatures (> 55 °C) to ensure thermal comfort limiting the heat exchange surfaces. On the other hand, fan coils can be used as hydronic terminals. They can operate at lower temperature, but they are usually not selected for residential buildings because of aesthetic reasons and noise issues due to fan operation. Therefore, radiators or fan coils? Both terminals have pros and cons. This study aims at solving such a dilemma by proposing a novel hydronic terminal, the fan radiator, which couples the mentioned systems. Like radiators, it consists in uncovered (without a case) coils, but these are finned. Like fan coils, it has a fan, but this works at lower speed (below the coils), thereby implying lower noise. A computational fluid dynamic (CFD) optimization is performed through the coupling between COMSOL Multiphysics^® − CFD modeling and simulation − and MATLAB^® − optimization engine − to design the fan radiator. A multi-objective genetic algorithm is implemented to optimize different morphological, geometrical and fluid-dynamic variables related to the system design. The model consists of a single convector channel. The considered objective functions are the system's thermal power output to be maximized and pumping power to be minimized. Fan operation/speed is limited in a range that avoids noise issues. A Pareto approach is implemented to find optimal tradeoff solutions, which are able to combine the pros of radiators and fan coils by solving the related cons. Indeed, the found optimal design solutions unveil that fan radiators can provide the same thermal power of radiators with the same encumbrance but working at lower temperatures. Therefore, they can be coupled with efficient or renewable energy systems promoting building energy efficiency and urban sustainable development. In addition, fan radiators can be used for space cooling too, ensuring thermal comfort throughout the year.