E. Iribar-Solaberrieta, I. Ruiz de Vergara-Ruiz de Azua, C. Escudero-Revilla, D. Perez-González, J.M. Hidalgo-Betanzos, J.M. Sala-Lizarraga
Keywords: active facades, PASLINK test cell, building simulation, free heating, building energy efficiency
Summary:The goal of this research project is to provide free heating by using active facades in a social housing building with 32 dwellings that is located in the North of Spain. Thereby, it was necessary to characterize the thermal performance of active facades so as to optimize their implementation in the building. The analysis was carried out by both virtual and experimental characterizations of a facade model and a monitored building. To begin with, this study collects the experimental results of some active facades which were tested in sample-scale. The evaluated active facades group were composed from conventional active systems, such as Trombe Wall, through solutions as photovoltaic facades. These facades were tested in outdoor conditions using a traceable and precise methodology. The testing equipment used is a PASLINK test cell developed by DYNASTEE (DYNamic Analysis, Simulation and Testing applied to the Energy and Environmental performance of building) network at the Basque Government Laboratory for the Quality Control in Buildings. The traceability of the results is guaranteed by three assumptions: a standardized testing methodology, the use of powerful tools for data analysis by parameter identification techniques and participating in a round robin test to detect and correct uncertainties in the results. Accordingly, these tests not only showed the efficiency of different active facades, but they also provided detailed information to define a mathematical model of active elements operation (such as ventilated cavity’s convective behavior) to input them in building scale simulation. In this way, a considerable amount of dynamic simulations were conducted by TRNSYS to evaluate the studied cases. In this preliminary stage of characterization, the design principles were corrected in order to improve the thermal performance of these active facades. Either tests or simulation results demonstrated that the active facade optimization should be carried out focusing on the use of the evacuated heat by convection in the ventilated cavity through an air extraction forced system. Thus, several design variables have proven to be crucial in the building-scale simulation, such as the width of ventilation channels, type of materials, solar absortivity, orientation… and their adjustment permits to maximize the amount of energy captured within the cavity and to fit the operation of every active system with the specific climatic conditions. Finally, these design principles were applied in the construction of the aforementioned social housing building. Three different types of facades were installed along the South orientation of the building: a standard passive system; a trombe wall with forced air extraction system where the air is directed into the building dwellings within the heat recovery ventilation system; and finally, a ventilated facade with a micro-perforated plate that has a forced air extraction system linked with a heat pump which supplies the heating demand. These facades have been monitored in order to verify the simulation results. Furthermore, a relevant criteria has been defined to adjust the operation of these active elements and, in consecuence, to find the optimal renewable system that provides free heating to tenants.