Experimental comparison of residential heat accounting systems at critical conditions

The individual accounting of thermal energy in residential buildings (heating, cooling, hot water) is considered a very essential tool for increasing energy efficiency. In fact, the availability of real time energy consumptions data, typical of smart metering, enables end-users to identify the causes of energy waste and to adopt adequate strategies to improve their energy efficiency. In such scenario, modern devices for thermal energy metering and accounting are nowadays spreading more and more, despite their metrological issues still have not been fully investigated, especially at critical installation and operative conditions. In this paper the authors present the results of an experiment aimed to assess the metrological performance of both direct thermal energy meters and indirect systems for heat sub-metering on the field. Some critical operative metrological influences concerning the different available heat accounting methods have been also investigated and the main metrological issues are here presented. The results of the tests clearly show different metering and sub-metering methods are not always fully compatible one each other. Furthermore, the lack of specific installation standards leads the metrological performance of such devices to be greatly dependent from the ability and competence of the installer