AIVC - Air Infiltration and Ventilation Centre

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Remedies for condensation and mould

Surface condensation and mould affect about 15 percent of the UK housing stock. This paper reports BRE studies in occupied dwellings on the effectiveness in various situations of a range of remedial measures, which included improvements to thermal insulation and heating, and the provision of extractor fans and dehumidifiers. The flats and 2-storey houses involved were all of traditional construction with brick walls and pitched roofs.

Thermal bridges: a two-dimensional and three-dimensional transient thermal analysis.

Thermal bridges are parts of the building envelope where, due to the two-dimensional or three-dimensional character of the heat conduction, either the inside surface temperatures are rather low, which can cause condensation, or the heat losses are rather high. In this paper thermal bridges are analyzed by numerical methods, shortly described in the first section. They are based on energy balance techniques.

Prevention of moisture damage by ventilation of the foundation.

Rising moisture from the ground has caused quite a lot of damage on foundations of Swedish buildings, in particular for the type concrete slab on the ground. Some of these constructions may be repaired by mechanical ventilation, for example below the floor or below the concrete slab , if there is an air-permeable layer below the slab. Summarized results from a few field studies and tests, which have been going on for a period of 2-3 years, are reported. Different methods with mechanical ventilation systems have been found to work quite well so far, i.e.

Condensation damage to timber frame housing.

This paper presents and discusses results of moisture transfer into timber frame constructions. The two mechanisms of transfer are diffusion and bulk air movement. Three defects in construction were monitored punctured vapour barrier, continuous path via an electrical socket and discontinuities at junctions. The study has shown that, under steady-state conditions condensation can take place, while under varying conditions both condensation and evaporation occur. This second case is typical of the building in use, and can prevent high levels of moisture existing in timber components.