Desacoplamiento del Coeficiente de Perdida de Calor de un edificio en uso aplicando el método de decaimiento del CO2

Résumé

The building energy performance not only depends on the thermal parameters related to the building’s envelope, but also with the installed services and its intended use. The building’s use is a difficult parameter to control; therefore, to reduce the discrepancies between the designed energy performance and the real one, is critical to correctly characterize the buildings envelope and buildings systems against real data. It is necessary to do with a minimum set of sensors; then this real data should be analysed with robust methodologies. If all this is fulfilled it would be feasible to integrate this methodology in the actual domotic systems of buildings. Many in-use buildings should be monitored in the next years to obtain their thermal characteristics in order to improve and / or demonstrate their energy efficiency, and thus fulfil the European guidelines derived from the energy reduction strategy in the European Union. In the FP7 A2PBEER project, a multi-storey office building of the University of the Basque Country has been vigorously evaluated with in-use and operation offices. The thermal parameters analysis’ studies has been made floor by floor and for the whole building. The initial objective of the study has been to propose modifications to the existing ISO 9869 method and to the existing the Co-Heating method to make them usable with real monitored data of in-use buildings and thus obtain its envelope main thermal characteristics: The Heat Loss Coefficient (HLC), which considers the transmission (UA-value) and air infiltration (Cv) losses (HLC = UA + Cv), and the solar aperture (Sa value) floor by floor and for the whole building. This office building had no ventilation system during the monitoring period. Based on these estimated in-use HLC values, the measured metabolic CO2 concentration values have been analysed using the decay method for anthropogenic CO2 concentrations. This decay method analysis has permitted to estimate the Air Change per Hour (ACH) of each floor in a daily basis. Based on those ACH values the air infiltration heat loss coefficients (Cv) of each floor have been estimated and then the HLC has been decoupled by means of the simple expression UA = HLC – Cv. This paper is focused on developing this decoupling method that seems promising since it will let us know to what extent the heat losses from a building envelope are due to air infiltration (or ventilation) losses or due to transmission losses.