Symbolic thermoeconomics in building energy supply systems

The advantages in applying the exergy concept and exergy efficiencies to evaluate the performance of energy systems in the building environment, contributing to the reduction in the use of high quality energy sources is currently known. Although Thermoeconomics has been widely applied in energy systems at building level Symbolic Thermoeconomics has been rarely used.This paper presents a review of Symbolic Thermoeconomics as a technique, based on the Exergy Cost Theory, to obtain general equations which relate the overall efficiency of an energy system and other thermoeconomic variables, such as fuel, product, exergy cost or exergoeoconomic cost, with the efficiency of each component, the total production and with certain coefficients which reflect the structure of the system.A case of a simple DHW facility is presented and Symbolic Thermoeconomics is applied in the demand-driven model to obtain general formulas which are valid for any state of the system, explaining the cost formation process. A TRNSYS simulation of the plant is performed and the results obtained are applied in order to obtain numerical values of the thermoeconomic variables and particularly the production costs which are decomposed into its different contributions, due to the external resources, equipment investment and waste generation.