Analysis of the influence of multiple-skin facade models on the overall energy demand of office buildings

Multiple-skin facades have gained an increased popularity amongst designers whose desire is to build energy conscious, sustainable office buildings. In order to analyze their performance, calculation models have to be implemented in dynamical energy simulation tools. This paper compares different models to predict the energy performance of different types of multiple-skin facades. A mechanically ventilated airflow window, a naturally ventilated double-skin facade and a mechanically ventilated supply window are modeled. First, the temperature profiles as calculated by four models with different degree of complexity are compared against those measured in a mechanically ventilated airflow window and a naturally ventilated double-skin facade. It is shown that more complex models better estimate the measurements. Secondly, the calculation models are implemented in a building energy simulation tool to analyze the yearly energy performance of an office building. As there are no energy measurements available, the most complex model is used as a reference here. All models show the same tendencies: the mechanically ventilated airflow window has the lowest heating demand, but the highest cooling demand, while the mechanically ventilated supply window has the lowest cooling demand. The differences between the less complex models and the reference are important and amount up to 18 % for heating and up to 13 % for cooling. The tendencies, however, cannot be generalized.