Metrological characterization of a new direct heat accounting device

The new Energy Efficiency Directive leads to a strong incentive to the installation of heat accounting systems as an essential tool to increase energy efficiency of buildings. This is also facilitated by the spreading of district heating networks more and more extended and to the return to central heating plants in buildings, more efficient and less polluting than traditional individual ones. Heat metering and accounting is now carried out by the so-called direct systems (i.e. heat meters) and indirect (i.e. heat cost allocators, insertion time counters compensated whit flow temperature or with the degree-days). On the other hand, both the metrological characteristics of such systems and the constraints in terms of installation and managing of heating plants lead direct and indirect systems to uncertainties in heat accounting sometimes far above the accuracy limit of 5%. In this paper the authors present the results of an experimental characterization of an innovative integrated system for heat accounting made up of an electronic valve, a static flow-meter and a temperature sensor pair. The system can be installed on the return pipe of each radiator of the heating plant and connected with a remote control unit and with a single temperature sensor installed on the feed pipe immediately below the central boiler.