Analytical solutions are derived for calculating natural ventilation flow rates in a single-zone building with two openings when no thermal mass is present. In these solutions, the independent variables are the heat source strength and wind speed, rather than given indoor air temperatures. Three air change rate parameters a, B and y are introduced to characterise respectively the thermal buoyancy force, the conduction heat loss effect, and the wind force. The wind can either assist the buoyancy force or oppose it.

Ventilation systems using variable airflow are useful in urban areas. Due to outdoor pollutionand the indoor load from pollution or thermal sources, it is important to vary the airflow. Thismust be done without disturbing the control of the total distribution. To analyse suchproblems, there is need for a design aid. This paper presents a first version of a modularsimulation program working in the IDA environment. The program is based on a set ofindividual component-models in the NMF (Neutral Model Format) language.

A humidity controlled air flow terminal device works as a humidity sensor : its openingsurface varies according to relative humidity inside a room in order to match air flow rate topollution. These components are fouling up when used during several months.In a laboratory, an air flow with a high rate of particules is fouling up five identical air devicesin a few hours. Considering a constant relative humidity, the impacts on two devices aresimilar : it seems that artificial fouling tests can be reproduced.

The Dutch organization for applied scientific research TNO in Delft developed asystem of Controlled Natural Ventilation (CNV). It is produced by the Dutchventilation fm Brake1 in Uden.

A self administrated questionnaire was mailed to over 300 dwellings in blocks of flats usingthe wall exhaust. In almost all the dwellings there was a controllable ventilation unit. Theunits were either a mechanical exhaust ventilation system type with outdoor air inlets ormechanical supply and exhaust ventilation system with heat recovery and outdoor air intakeon the wall. In the questionnaire, the daily use of ventilation unit, noise levels as well as odorsand their sources in the dwellings were asked.

In this study, we have tested more than 80 silencers of different sizes (from O 250 to 1250), length, insulating thickness and with or without central pod. The attenuation, measured at several velocities between 0 - 8 m/s, was compared to some literature estimations and has shown strong differences. They induce that literature estimations should be used only in the same conditions they were made and, not too widely, as it is currently done because real knowledge of the influence of parameters is lacking.

The inadequate dissipation of hurnidity fiom living spaces and bathrooms has become asignificant problem area in recent years. This can be attributed both to the replacement of old,poorly sealed windows by new windows with better seals, and to the increasing use of tilesand other building materials which hinder an adequate absorption of water vapour.The residents tend to reject repeated opening of the windows for ventilation purposes ongrounds of the ensuing energy costs.

A wind tunnel study was carried out to investigate the airflow through courtyard and atrium building models. Ventilation strategies resulting from the use of different atrium roof pressure regimes (positive pressure and suction) were examined and compared with the performance of the open courtyard. The model buildings were monitored both in isolation and in idealised urban environments of varying group layout densities. The effect of wind direction was also observed.

The trend towards improving building air-tightness to save energy has increased theincidence of poor indoor air quality and associated problems, such as condensation onwindows, mould, rot and fungus on window frames. Mechanical ventilation 1 heat recoverysystems combined with heat pumps offer a means of significantly improving indoor airquality as well as providing heating and cooling required in buildings.This paper is concerned with the development of a novel ventilation I heat recovery systemfor the domestic market1.

A computational study had been carried out on hot and cold air interaction across the door of an urban transport vehicle. The studies show that within 20 s after the door is opened all cool air beside the door of the vehicle would flow out when the amb