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.
States that the new UK building regulations show a recognition of the importance of controlling the build-up of moisture and indoor air pollutants in the home. Concentrates on how designers can meet the need for adequate ventilation without wasting excessive energy.
Describes a retrofit carried out on a building of 36000 m3 volume in Northern Italy which eliminated air infiltration around windows using silicone caulking. The energy balance of the building was evaluated experimentally before and after the retrofit. Verifies the impact of unwanted air infiltration on a building's energy use. States that the analysis of the experimental data made it possible to extend the results obtained from town houses by other authors to apartment buildings.
This report examines three devices (exhaust fan, air-to-air heat exchanger and exhaust air heat recovery heat pump) which could be used to increase the ventilation rate of a tightly constructed house to a level sufficient to keep indoor air pollutants and moisture to acceptable concentrations.
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