Assessment of single-sided ventilation with acoustic shutters on windows

International audienc

PERFORMANCE EVALUATION OF NATURAL VENTILATION THROUGH WINDOWS WITH HORIZONTAL BLADE SHUTTERS

International audienceThe use of shutters can reduce the drawbacks of natural ventilation on intrusion risks and acoustic problems. However, when the shutters are used with single-sided ventilation, the air change rate is too deeply reduced. This study shows that the air change rate is maintained to acceptable values in cross-ventilation contrary to single-sided natural ventilation for horizontal blade shutters. An experimental investigation is carried out on a hotel room with or without shutter in Corsica, France. The air change rates are given out by the tracer gas technique using carbon dioxide. The concentration decay method is applied and the decrease of tracer gas concentration in the room is measured by 9 CO 2 sensors in various positions. Air change rates are given for different wind orientations and speeds. Even if the shutters reduce by 45% the window opening surface on one side, the air change rate can be kept up to 80% of that with a plain opening without shutter since it is limited by the other side window which has smaller opening surface

Silencer design for awning windows: Modified Helmholtz resonators with perforated foam

International audienceIn order to dissipate sound which passes through an open awning window, we have developed a hybrid absorber made of a modified Helmholtz resonator with perforated foam. Generally, acoustic absorbers are divided into two major categories. The first one is porous materials which dissipate the acoustic wave in a visco-inertial form and heat. The second category is systems which absorb the energy of the acoustic wave by resonance. The aim of this work was to design a hybrid absorber which incorporates the benefits of the two categories for both high frequencies (conventional foam) and low frequencies (resonator). After describing the concept and the principles, we present the prototype which was built and tested under laboratory conditions between two reverberant rooms to attenuate the sound when an awning window is open. The prototype allows reduction of noise transmission (up to 6 dB) at low and high frequencies