Condensation is not always visible. The droplets of water on cold surfaces are obvious but in building components, hidden from view, condensation can cause much greater problems than a puddle of water on a windowsill.
The air holds a certain amount of water vapour, and the air’s capacity to hold water vapour reduces as the air temperature reduces. Therefore, as humid air cools it reaches a point where it can no longer hold all of its moisture and the water vapour in the air condenses into water. The temperature at which air reaches its dew point is often referred to as the dew point temperature. However, the dew point temperature is not a fixed temperature that occurs on a surface; it is a travelling threshold that moves as the temperature reduces throughout the building element.
As one moves through the wall from warm interior to cold exterior, temperature decreases through each of the layers of plaster, brick, insulation and render. There will be a point at which the temperature falls to the dew point and moisture will appear. This area of condensation is known as the condensation plane. how vapour drive and dew point interact inside wall assemblies shows how the position of the condensation plane can change as the thermal conditions in either area of the wall are altered. If you are looking for Air Conditioning Stroud, see https://acecc.co.uk/air-conditioning-near-me/air-conditioning-stroud/.
However, cooling a room can cause problems with condensation in buildings, especially older solid-stone or solid-brick buildings found throughout the Cotswold valleys. As the room is cooled, the surface temperature of the interior of the building will be reduced and the temperature gradient through the wall fabric will be increased. In modern cavity-insulated buildings, this is usually a problem managed by the insulation in the cavity. However, in buildings without a cavity (such as some older houses in the Stroud area) the condensation plane will move into the solid masonry and, with no means of ventilation or drainage, cause dampness. Damp in buildings causes timber to rot, plaster to degrade and for black, toxic mould to grow.
The resulting damp penetrates into the timber work of a building causing decay and also penetrates into the older plaster work causing it to deteriorate. Most damage is visible only when it is too late and further exacerbated by black and pink mould growth.
If you are thinking of installing air conditioning in an older building in the Stroud area, this should be considered before selecting a type of installation and whether or not measures for vapour management will be required. The cooled air will, of course, feel wonderful in the room, but what is happening in the walls is another matter.
