The development of information technologies allowed digitalization in different fields, as in, for instance, the engineering field, which is one of the most challenging fields, since smart supported solutions can bring important benefits to society in general. The energy sector is already experiencing gradual digitalization with important advances to be made in the upcoming next decades. Moreover, the role of smart energy technologies is a significant one in the ongoing energy transitions, since it can ensure various technological upgrades, especially in the case of hybrid energy systems or in different energy generation technologies in general. Efficiency improvement of energy technologies, processes, as well as specific system components is possible through the implementation of smart technologies. Additionally, environmental footprints of different energy technologies could also be reduced by the implementation of smart and Internet of Things (IoT) supported devices or products. However, the development of smart energy technologies needs to be provided in a controlled manner to reach sustainable criteria. Namely, the rapid rise in various smart technologies is potentially causing fast consumption of limited raw resources needed for assembly of electronic equipment; on the other hand, we are potentially being faced with the increased generation of electronic waste and release of other pollutants. Development of smart technologies should be carefully monitored to ensure long‐term feasibility and environmental suitability. Finally, the progress of smart energy technologies strongly depends on further advances in the development of electronic components, software solutions, sensor technologies, and general network infrastructure. Smart energy technologies are for certain an opportunity for humanity, which brings important and useful benefits.

This special issue is related to selected papers from the 4th International Conference on Smart and Sustainable Technologies (SpliTech2019), which was held in Split and Bol (Island of Brač), Croatia, in June 2019. The SpliTech2019 event linked various engineering professions and provided a platform for a vibrant and sounding discussion between researchers and professionals from the industry. The conference hosted over 200 delegates from 35 countries worldwide. The focus of the conference was directed to the role of smart technologies in the technological development of societies as well as the impact of the smart technologies on the use of resources. Over 200 presentations were delivered and related to the fundamental and applied research from interdisciplinary research topics. Tutorials, workshops, as well as round‐table discussions were organized to promote research‐based solutions with industrial applications. A traditional, “Meet the Editor” workshop was organized and hosted distinguished editors from reputable peer‐review journals to support young and less experienced authors.

Finally, I would like to express my appreciation to the keynote and invited speakers, to the technical program committee members, session chairs, reviewers, and to the valuable authors for their general contribution. Special thanks to the SpliTech2019 organization team, who made this event possible and to the conference sponsors for their continuous support.

Special thanks to Prof. Dr. Ibrahim Dincer for his overall support and efforts during the initial preparation as well as for the realization of this special issue. Prof. Dr. Sandro Nižetić would also like to acknowledge the support of the Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture together with the University of Split and to the IEEE Communications Society.

信息技术的发展允许在不同领域进行数字化，例如工程领域，这是最具挑战性的领域之一，因为智能支持的解决方案可以为整个社会带来重要利益。能源行业已经在逐步实现数字化，并在接下来的几十年中取得重要进展。此外，智能能源技术在不断进行的能源转型中扮演着重要的角色，因为它可以确保各种技术升级，尤其是在混合能源系统或一般而言不同的能源生产技术中。通过实施智能技术，可以提高能源技术，流程以及特定系统组件的效率。另外，通过实施智能和物联网（IoT）支持的设备或产品，还可以减少不同能源技术的环境足迹。但是，需要以可控的方式提供智能能源技术的发展，以达到可持续的标准。即，各种智能技术的迅速发展潜在地导致快速消耗组装电子设备所需的有限的原始资源。另一方面，我们可能正面临着电子废物产生的增加和其他污染物的释放。应仔细监控智能技术的开发，以确保长期的可行性和环境适应性。最后，智能能源技术的进步在很大程度上取决于电子元件开发的进一步进步，软件解决方案，传感器技术和一般网络基础架构。智能能源技术在一定程度上给人类带来了机遇，带来了重要而有益的利益。

本期特刊与2019年6月在克罗地亚的斯普利特和波尔（布拉奇岛）举行的第四届智能与可持续技术国际会议（SpliTech2019）的部分论文有关。SpliTech2019活动将各个工程专业联系起来并业界研究人员和专业人士之间进行充满活力，更有意义的讨论的平台。该会议接待了来自全球35个国家的200多名代表。会议的重点是智能技术在社会技术发展中的作用以及智能技术对资源利用的影响。发表了200多个演讲，涉及跨学科研究主题的基础和应用研究。教程，讲习班，组织了圆桌讨论会，以促进基于研究的解决方案与工业应用。举办了一次传统的“与编辑见面”研讨会，并邀请了来自著名同行评审期刊的杰出编辑，以支持年轻和经验不足的作者。

最后，我要感谢主旨演讲和特邀发言人，技术计划委员会委员，会议主席，审稿人以及宝贵的作者的一般贡献。特别感谢SpliTech2019组织团队使这次活动成为可能，并感谢会议赞助商的持续支持。

特别感谢易卜拉欣·丁塞尔（Ibrahim Dincer）教授在最初的准备过程中以及在实现这一特殊问题上给予的总体支持和努力。桑德罗·尼采蒂奇（SandroNižetić）教授还要感谢电气工程，机械工程和海军建筑学院以及斯普利特大学和IEEE通信协会的支持。