Passive strategies to improve summer comfort in the renovation of a free-standing residential building: evaluation of horizontal and vertical louver systems

Re-use and renovation of buildings are core strategies towards a rational environmental policy. It preserves not only the city memory and cultural values but also diminish the use of non-removable natural resources and save energy. However, many after-war modern buildings in Europe have poor climatic design which can leads both to uncomfortable indoor conditions during hot summers and to a high energy consumption by cooling. This study focuses on the simulation, evaluation and improvement of indoor thermal comfort in an existing free-standing residential building in Palermo, Sicily (see ref. 1,2). The evaluation and quantification of the (dis)comfort is a result of simulations carried out by coupling Computational Fluid Dynamics (CFD) and Building Energy Simulation programs (BES). Values of indoor air speed and pressure coefficients are obtained from CFD calculations and further used as input in BES calculations and comfort analysis. Two BES programs EnergyPlus and TRNSYS are compared. Both programs are coupled with airflow simulation program COMIS. Simplified and improved calculation methods are respectively used in CFD and BES programs for the cases of vertical and horizontal louver systems. Special attention has been given to the physical model, boundary conditions and influencing parameters. The results show that the use of CFD calculations is required for the prediction of indoor air speed which is a necessary parameter for comfort calculations. Concerning the comfort analysis, the results show that in this particular case the overheating problem could be improved by passive means by the application of several strategies like the use of existing balconies with external louver systems and whole day natural cross ventilation. (1) Karelien Vaes, Sara Van Praet, Development of sustainable renovation strategies, concentrated on natural ventilation, for residential buildings in Palermo. Master thesis, K.U.Leuven, 2007. (2) Sofie Mols, Hanne Van Beurden, Passive concepts for thermal comfort with focus on fixed solar shading devices. Master thesis, K.U.Leuven, 2007.