Enhancement of ventilation efficiency in residential buildings by pulsating air-flow

Abstract

Contrary to conventional air-conditioning systems in non-residential buildings, the air-flow conditions are almost never considered in ventilation systems for residential buildings. Both the air inlets and the outlets are usually located at unfavourable places. This situation culminates in large buildings with many flats, where simplest supply-air apertures are installed with respect to cost restrictions. With small air flow rates, the ventilation efficiency is very poor due to a lack of air mixture. In order to improve the situation, a new supply air aperture has been developed recently. The air flow rate is designed to vary with time, with a low auxiliary energy requirement, with clear maxima and otherwise reduced flow rate. Hence, the corresponding momentum was expected to improve the air mixture in the room. First measurements confirm that the transient flow conditions allow high intrusion depths and a good mixing of the air. The pulsating airflow reduces the risk of draughts and increases both ventilation efficiency and thermal comfort in the living area. Moreover, the energy efficiency is improved as the average air-flow rate can be reduced.