In recent years, poor indoor climate has increasingly been seen as the cause of health problems for building occupants. Today, there is good evidence in some areas why such problems arise. Unhealthy substances given off by various building materials, the existence of mould and general air pollution are the main causes. In general, the most important way to remedy the problem is improved ventilation. Poor upkeep and maintenance have led to a decline in the performance of existing ventilation systems.

The Dutch "E'novation" program is a national demonstration program in which dwellings with high energy consumption, moisture and mould problems and poor indoor air quality were renovated, with special attention to the selection of the heating and ventilation systems, thermal insulation and the buildings' physical details. A number of indoor air quality parameters were monitored before and after renovation, showing an important improvement in the indoor air quality. Moreover, total energy consumption decreased by 33%, which meets the targets of the Dutch National Environment Policy.

Describes how basic studies (detailed simulations) have been used to define the calculation of energy losses due to ventilation in French regulations, and the "ongoing" research aiming towards a better assessment of air quality.

An effort has been made to gather the information available about duct cleaning. The emphasis in the survey was on the hygienic aspect of the cleaning of supply air ducts. Most of the literature deals with cleaning of exhaust ducts. Guidelines for the cleanness of ductsurfaces have been given by some organizations, but the scientific basis for such guidelines needs more research.

This report is meant to give a brief survey of existing publications about the sick building syndrome. It reviews investigations from several different countries.

After a short introduction of the "age of air" concept in ventilation, a theorem of conservation for the age of air at the outlet is presented. Restrictions to validity and two applications (to measurements and numerical simulation) are described. A rigorous analytic proof is shown based on field theory.

The contribution of new and used fine bagfilters to indoor air pollution has been determined in a laboratory study by a trained panel as well as by TVOC measurements. The used filters were all taken out of air handling systems which run with full outdoor air supply. The time that a used filter had been situated in the ventilation system until it was taken out and was studied in the laboratory varied from two to ten months. The new filters did not pollute significantly in comparison to the used filters. However, all used filters polluted the air instead of cleaning it.

Pressure distributions around buildings are important factors affecting the air infiltration and ventilation of a building and consequently energy. Existing methods of determining pressure coefficients are costly both in terms of time and resources. This report aims to show the benefits of using a computational fluid dynamics (CFD) program in this field. Work was carried out to predict the pressure distribution around a sheltered building. The CFD program was used to investigate how pressure coeffieicnts vary with building separation and the degree of shelter offered by an upwind building.

This work examines the application of the constant-injection and pulse-injection tracer gas techniques for measurement of airflow in rectangular ducts. Experiments were carried out in ducts with aspect ratios of 1,2, and 4. Tracer gas measurements were generally similar to measurements made using a pitot tube. Relationships for the friction-factor and hydrodynamic entrance length are presented for Reynolds number between 73,300 and 395,000.

The effect of wind on building ventilation is determined by pressure coefficients that depend on many factors such as building geometry, wind direction, mean and turbulent atmospheric boundary layer velocity profiles, and thefactor to be considered here: shelter by upwind obstacles. Pressure coefficients on the exterior of building are defined by normalising the pressure difference between that measured on the surface and a reference pressure by an appropriate stagnation (or velocity) pressure.