Internet of Things (IoT) as an emerging technology provides interconnections between various objects with three features, i.e., anything, anyplace, and anytime. Due to the high number of objects in the IoT and their proximity to humans, energy efficiency is a fundamental requirement for this technology. In general, paying attention to energy efficiency at various levels of IoT leads to Green IoT (GIoT), which decreases costs while reducing human health threats. In this paper, the effective measures that can be taken to achieve GIoT are investigated at various levels, including hardware, software, communication, and network architecture. In addition, opportunities, challenges, and applications of GIoT in various aspects are considered to clarify its limitations. Given the crucial significance of environmental preservation in human life, business models and business platforms of this technology are investigated that have introduced by active IT companies. Moreover, open issues and directions of GIoT, including standardization, technical challenges, innovations, and security are reviewed for further research. It is hoped that effective policies for GIoT development will be provided by addressing the salient challenges and formulating appropriate standards. The investigations indicate that the green goal should certainly be addressed in the overall cycle of GIoT, including design, production, utilization, and ultimately disposal/recycling.

物联网（IoT）作为一种新兴技术，提供了具有三个功能的各种对象之间的互连，即任何地方，任何地方，任何时间。由于物联网中的对象数量众多且它们与人类接近，因此能效是这项技术的基本要求。总的来说，关注物联网各个级别的能源效率会导致绿色物联网（GIoT），从而在降低成本的同时减少对人类健康的威胁。在本文中，从硬件，软件，通信和网络体系结构等各个层面研究了可实现GIoT的有效措施。此外，考虑了GIoT在各个方面的机遇，挑战和应用，以阐明其局限性。鉴于环境保护在人类生活中至关重要，研究活跃的IT公司引入的该技术的商业模型和商业平台。此外，还审查了GIoT的未解决问题和方向，包括标准化，技术挑战，创新和安全性，以进行进一步研究。希望通过解决重大挑战并制定适当的标准，为GIoT发展提供有效的政策。调查表明，绿色目标当然应在GIoT的整个周期中得到解决，包括设计，生产，利用以及最终的处置/回收。和安全性进行审查，以进一步研究。希望通过解决重大挑战并制定适当的标准，为GIoT发展提供有效的政策。调查表明，绿色目标当然应在GIoT的整个周期中得到解决，包括设计，生产，利用以及最终的处置/回收。和安全性进行审查，以进一步研究。希望通过解决重大挑战并制定适当的标准，为GIoT发展提供有效的政策。调查表明，绿色目标当然应在GIoT的整个周期中得到解决，包括设计，生产，利用以及最终的处置/回收。