The Impact of Double Skin Façade on the Energy Consumption of Office Buildings under the Tropical Brazilian Climate

Double skin façade (DSF) is an attractive architectural element in modern office buildings that, while giving a transparent appearance to buildings, can potentially be able to moderate the indoor thermal conditions and reduce energy demands. Developments in warmer climate countries such as Brazil are beginning to consider the application of DSF technology as a solution to improve thermal and energy performance in their buildings. Building upon the experience of a comprehensive research programme on the study of the thermal performance of office buildings with DSF, from which key design parameters affecting the thermal behaviour of DSF have been identified and evaluated, this study aims to examine the impact on energy consumptions. Using an office building model with an optimised DSF, this study assesses the energy consumptions when the building is fully air conditioned or operated under a mixed mode ventilation strategy. Models with similar characteristics but with single skin façade are also studied for comparison. Computational models developed for this study are evaluated using the dynamic simulation program IESVE which integrates building fabric thermal behaviour and environmental systems operating under the climatic conditions of the Brazilian city Rio de Janeiro. The results indicate that natural ventilation can provide the necessary thermal comfort in over 34% of the year in the building model with DSF under mixed mode ventilation strategy, that can potentially reduce 21% of annual cooling energy when compared to the fully air conditioned model. However, energy savings due to the addition of DSF alone are relatively small - 15% in full air conditioned model and 6% in mixed mode ventilation model. The benefit to thermal energy consumption is therefore marginal. However, comprehensive whole life evaluation is needed to provide a holistic assessment when other beneficial contributors, such as lighting, smart glazing and integrated PV are taken into consideration.