English

To make an evaluation of ventilation systems, numerical computation was carried out for three dimensional, isothermal, and turbulent flow schemes. It was found that there exists an optimum position for an inlet in relation to an outlet whereby the most effective ventilation can be attained. In addition, similar to the results for the two dimensional computation, the slope of the concentration decay is virtually constant and independent of the position in the room, so the mixing factor derived from this slope can be used as an index of the ventilation efficiency.

Describes a demonstration project to show that, in well sealed houses, trickle ventilators can provide an opening large enough to reduce condensation and odour problems, but small enough to avoid any significant increase in energy use.

Discusses ventilation requirements to achieve acceptable air quality. In many cases, this would lead to unacceptable energy costs, so instead recommends setting standards for heat-exchanger systems, for filters that can control particulates, hydrocarbons and radon gas, and for details such as flow direction and system maintenance. Also standards for 'pollustat' systems should be encouraged by which four surrogate pollutant levels would be kept below suggested threshold levels in all conditions of building use and occupancy.

Discusses methods of preventing condensation: dehumidification, ventilation, controlling vapour flow; insulation and heating. Particular attention is paid to interstitial condensation and condensation in roofs

Summarises risk by building type and the various physical processes involved in moisture transfer and condensation.

Discomfort due to stuffiness and adverse temperature gradients may occur in well insulated rooms with low levels of natural ventilation. Using methods previously applied to studies of convection in the atmosphere, a model of the room air movement

The advantages and disadvantages of various ventilation systems have been assessed in Germany over the past four years. The programme covered research in unoccupied test rooms as well as in occupied buildings. Results are presented, and the possibilities and limits for energy saving while meeting comfort requirements are discussed.

In order to determine ventilation performances in hot arid regions a transient program was simulated for a single room with glass windows. The calculations were done on climatic data of a typical city close to the central desert of Iran. Results indicate that the incident solar radiation to the room has a high influence on the room air temperature.

Evaluates results of the 'Ventilation in Residential Buildings' research programme of the German Federal Ministry for Research and Technology. It was found that conventional ventilation methods based on infiltration and window opening cannot secure proper air quality and at the same time provide energy conservation and user comfort, nor can intelligent ventilation habits be expected of the average user, for subjective and objective reasons. All ventilation systems evaluated had shortcomings.

In new buildings, the requirements for indoor air quality and energy efficiency cannot be met with natural ventilation. In renovations of existing buildings it is, however, often difficult or uneconomic to install a mechanical system. What is often forgotten is that the conditions for natural ventilation will have changed, even if no alterations are made to the ventilation system.