English

Specific indoor air quality issues that have arisen in the UK in recent years have involved asbestos, formaldehyde, pesticide residues, radon and combustion products. Different measures have been taken with regard to each of these substances. In general, an education approach has been adopted, although national standards, industry self-regulation and some regulatory measures have been used. In the UK, control of ill defined, distributed or non stationary indoor air pollutants such as body odour, tobacco smoke and water vapour, is considered to be best achieved by suitable ventilation.

Most houses in the Netherlands are equipped with gas-fired heaters and cooking appliances, since large amounts of natural gas are available. Carbon monoxide poisonings occasionally occur due to the use of instantaneous water heaters (geisers) that are gas fired. An investigation was carried out to establish the carbon monoxide production potential of geisers under normal conditions of use. The study involved 254 houses: the results indicated that 17% of the geisers produced a carbon monoxide level of more than 50 microL/L in thekitchens where they were located, after 15 min of operation.

The influence of the various sources of pollution on the home environment in the Netherlands is reviewed, eg, outdoor air, gas-fired appliances, tobacco smoking and building materials. The pollutants carbon monoxide, nitrogen dioxide, particles and radon are discussed in more detail. Available data show that outdoor standards for air quality are often exceeded indoors. However, conclusions on exposure and health effects cannot be drawn until more data are available from random or stratified samples of houses.

Outlines some of the principles behind air driven aspects of moisture in buildings and illustrates how calculation methods and mathematical modelling techniques may be used to both predict and remedy associated problems. Primary remedies include a reduction in the generation of moisture, ensuring thermal integrity of the building and providing adequate ventilation. The use of dehumidification may also have a role to play. Mathematical models offer an inexpensive method for assessing design ideas at an early stage of development.

This paper reviews the work carried out in the Netherlands on moisture problems. In current air flow simulation models for buildings, moisture transfer and diffusion in and between rooms are not taken into account. The aim of the research project is the development of an integral hygrothermal model in which the above mentioned aspects are incorporated.

Over the last few years frequent cases of mould growth in dwellings have occurred. The problem is essentially due to an excessive moisture content of the building elements, which can result from hygroscopic adsorption or from frequent surface condensation.

Surface condensation and mould affect about 15% of the UK housing stock. This paper reports BRE work undertaken in occupied dwellings to identify the effectiveness of a range of remedial measures in various situations. The remedies investigated include the improvements to insulation levels, andheating systems, the provision of extract fans and dehumidifiers. The studies were undertaken in both flats and 2-storey houses, all of traditional construction with brick walls and pitched roofs.

Discusses case histories of rehabilitation work in flats and maisonettes in London, UK. It is clear from the results of these that the ventilation rate is inadequate for the lifestyle in the dwellings considered. Discusses provision of adequate ventilation by use of fans, vents and windows and use of thermal insulation.

Discusses ventilation efficiency and production rates of water vapour in residential buildings, using a three person flat of 100 m2 living area as amodel. The cold outer surfaces of a building are the critical ones regarding condensation. To avoid surface condensation, the ventilation requirement is that the air change rate must reduce the vapour content in the room air at least so far as to reduce the dew point temperature below the lowest surface temperature.

Summarizes the state of knowledge about combustion products, surface condensation and mould, formaldehyde and radon, and the guidance currently offered on their control in the UK. Statutory ventilation requirements are outlined and various measurement techniques described.