TdT: A tool for building thermal systems analysis and comparison

Abstract

This work describes the tool “Towards Dynamic Thermoeconomics” (TdT), which has been designed to analyse the thermal systems of buildings from a dynamic point of view for further thermoeconomic analysis, since HVAC systems consume a significant part of the global energy and have a significant environmental impact. TdT is presented as a versatile, open-source application developed in Python, which provides dynamic energy and exergy performances of components, as well as the most vulnerable points in the system to be optimised. As a novelty TdT introduces a new methodology for analysing inertial systems that defines non-periodic time intervals in which the tank temperature is Ttank,rep, thus avoiding misleading cost results. Two case studies are presented as examples of typical applications: a domestic hot water system and a heating system, analysed with TdT in eight different climatic locations in Spain. The corresponding results are extracted and analysed, with a particular focus on the influence of the outdoor temperature (T0) on both the exergy and energy efficiency of the components, the identification of irreversibilities and the total exergy consumption. It becomes evident that as the T0 increases by 38 %, the exergy efficiency of the boiler decreases in both systems, with an average yearly exergy efficiency decrease of 1.4 % on the DHW system. Furthermore, the boiler is the component with the highest irreversibilities, followed by the inertial and distribution components, information that could not be obtained from energy analysis. Ultimately, the TdT provides valuable insights and a novel methodology for analysing inertial components, which will improve the efficiency and sustainability of building thermal systems.