extract ventilation

The differences between extract ventilation and balanced ventilation are subject of many discussions in sales markets where both solutions have their share. Often, the differences are marked in terms of energy, because balanced ventilation is normally accompanied by heat recovery. But there is another difference in terms of the ventilation effectiveness of the system.This document reports experiments in a scale model of a house showing the difference between extract ventilation and balanced ventilation in ventilation effectiveness, and therefore in achievable indoor air quality.

Airflow characteristics in the air-conditioned spaces play an important role to obtain the comfortable and hygienic conditions. This paper utilizes a 3D time dependent Computational Fluid Dynamics (CFD) model to assess the airflow characteristics in four different air-conditioned spaces. It was found that the location of the air extraction port represents a critical design factor and would have a direct effect on the heat removal efficiency and the energy efficiency of the air-conditioning system from the airside wise.

In 2003, the World Health Organization received reports of ‘Severe Acute Respiratory Syndrome (SARS)’ in various parts of the World. Until 13 June 2003, there were 1755 people affected by atypical pneumonia in Hong Kong. While the mechanisms of the SARS a

In dwellings ventilated by extract ventilation there are common complaints of cold draught caused by the supply air entering the room through openings close to the windows. This paper reports on studies of unconventional ways to distribute the supply air in order to minimise the risk of such problems. Experiments have been done where the supply air device is located in the hall of an apartment. The ventilation efficiency in the rooms adjacent to the hall has been studied with open and closed doors. The behaviour of gravity currents has also been studied in scale models.

The project reported on here was designed to expand on previous studies of the problem of incomplete venting of the products of combustion from heating appliances in order to approach a more nearly comprehensive understanding of the extent and nature of the problem in the Canadian housing stock. The work was subdivided into seven separate but closely coordinated sub-projects