## 1 Introduction  
Sustainable development and controlling climate change can only be achieved with a safe and low-emission energy system. Its transformation involves, i.a., decarbonization of buildings responsible for approximately 36% of all CO2 emissions in the European Union. Around 40% of the consumption of final energy is spent on heating and cooling, from which most is used in buildings [1]. This sector is treated as pivotal in accelerating the reduction of emissions of the energy system. It is also a strategic industry in the context of energy safety, since according to the forecasts, till 2030, heating and cooling will account for about 40% of the consumption of renewable energy sources. Creating smart buildings and cities aims to improve the quality of life of their inhabitants and the protection of the natural environment. As mentioned in [2], smart grids and smart buildings feature optimized asset management, increase operational efficiency, ensure stable power supply, allow for real-time monitoring of system operation, or enhance the network's reconfiguration and self-healing ability. The application of smart meters enables a regular monitoring of power consumption and provides access to flexible rates [3]. Consequently, advanced heating systems can adjust heat supplies to weather conditions and contribute to reducing energy grid losses and emissions. On the other hand, a high number of connected meters and other IoT (Internet of Things) devices installed in smart buildings, as well as a significant amount of generated data create a challenge for the operators and maintainers. The impact of smart meters and their reliability on the safety of buildings and cities is growing [4] and therefore requires further study. Heat meters are used in central heating systems to calculate the consumed energy both in multifamily houses and single apartments or offices. Smart heat meters ensure that costs are settled based on the actual consumption and contribute to saving heat by inhabitants and reducing emissions, particularly in buildings with many tenants. Currently, as we found, approximately half of the heat meters installed in Switzerland are read manually. However, the number of meters read remotely, which belong to smart meters, increases year by year in Europe [5]. Recording heat consumption with the use of a smart meter can take place in one-hour intervals or even shorter. The information on the meter state can be directly sent to the operator, thanks to which it is possible to monitor and manage the network regularly. It is necessary to develop a uniform communication system to introduce the IoT technology for the billing of media and enable the delivery of telemetric data to one node. To ensure the interoperability of connected meters, the OMS (Open Metering System) group [6] was created in 2015 as a non-profit European organization gathering the leading meter manufacturers and operators. They are working on the standardization of smart meters (not only electricity meters) and a common communication protocol. Furthermore, the EU directive from 2012 with amendments from 2018 requires that by 25 October 2020, newly-installed heat meters and heat cost allocators should be remotely readable to ensure cost-effectiveness and frequent provision of consumption information [7; 8]. According to Article 9 of this document, all Member States should implement intelligent metering systems and smart meters, only if it is technically possible, financially reasonable, and proportionate in relation to the potential energy savings. The reliability of smart meters has a fundamental significance for heat distributors and consumers, since the quality of collected data, the correctness of billing of heat, and making proper decisions in managing heat distribution network depend on it.