Evaluation of discharge coefficients of large openable windows using full-scale samples in wind tunnel tests

Abstract

Discharge coefficients (CD) are key input data in the evaluation of energy performance of naturally ventilated buildings. Such buildings are characterized by large openings (windows, grills, vents) for which accurate experimental data are rarely available in the literature or from manufacturers. In order to contribute with an experimental method for assessment and with new CD values from windows typically found in Brazil and Germany, this paper describes a set of experiments assessing the discharge coefficient of these windows for cross-ventilation. Experiments were carried out based on the standard BS EN 13141-1:2004 set-up in a wind-tunnel with full-scale models. The investigated sample also comprised windows whose CD values were known for the validation of the method. Results for known windows are in line with previous work. Results of discharge coefficients for innovative windows (not yet available in the literature) were found. The work reduces assumptions in natural ventilation studies, contributing to the reliability of building performance assessment.