## 4 Discussion and Perspectives
In 2014, France had the lowest peak demand on record since 2004 [71]. Other EU countries' consumption profiles and peak demand characteristics remain to be validated for the smart grids from ongoing EU pilot projects [1]. At the regional level, zone policies and network characteristics vary. For instance, for the Netherlands, the barriers to fast deployment of smart grids are mostly uncertainty of the benefits, with only about 11.1% of the network contains renewable energy generation in 2015 [72], while a target of 14% renewables by 2020 in the Netherlands has been stated [73]. Meanwhile, Austria has a target of 34% renewable energy by 2020, and 100% self-sufficiency in energy by 2050 [74]. The main reason for this is the use of hydroelectricity as a huge energy reservoir to flatten the demand curve, which improves the renewable energy cost effectiveness by erasing the need for residential batteries. Austria is actually marketing itself as the 'battery of Europe'. Transnational collaborations and knowledge sharing initiatives between these types of countries are in progress, in order to learn from favorable conditions and to consider weak points, so as provide more solid initiatives [1]. For instance, in the Netherlands, there are some investment plans in operation until 2025, as the green hydrogen economy in north, which might be a solution for the electricity grid capacity and flexibility problems in a cost effective way, through combining with other renewable/sustainable energy sources [75]. The renewable energy seasonal surplus could be converted and stored as hydrogen, transferred across the country by the existing gas network (after minor conversion), and could be stored in salt caverns to provide seasonal flexibility, and to balance regional pros and cons, salt caverns and the dramatic decrease in renewable energy production during winter. Regarding energy efficiency and sustainable energy usage by EU citizens, the three-layer model usage will keep their motivations in pace, as feeling part of the energy transition. Smart products and services would give them the possibility to become greener or accomplish their economic objectives giving them a certain degree of freedom, meanwhile also providing the ability to the smart grid to optimize the shiftable load whenever available. Techno-economical approaches, or fully automated demand load control, or massive deployment of smart grids, would certainly bring resilience and efficiency from a technical and organizational perspective, which is of course a necessity [24; 25]. However, in the residential sector, if not combined with the stakeholders layer, these approaches might fail to make citizens become more energy resilient or sustainable. Furthermore, because they might not feel part of the energy transition, the usage performance of new technology devices might drop. Or even worse, it paradoxically increase citizens' consumption, as they may tend to consume more due to disempowerment resulting from the automated processes. Automated demand load would certainly reduce the peak demand, by risking this to be perceived as a real constraint for the residential sector. Even used to a moderate extent, if end-user perspectives are not taken into account, they will greatly reduce the acceptance of smart grids. Our three-layer model aims to highlight such interactions and the possible consequences, where the solution should come from all layers, not only from a top-down approach. The main barrier to smart grid deployments is the lack of multidisciplinary considerations for the residential sector where uncertainties are vast and objectives, consumption and production patterns, geographic attributes, local authority aims and policies are not identical.