Condensation, as the name suggests, is water which has condensed from warm moist air on contact with a cold surface.
Air holds water in the form of water vapour (moisture) warm air is able to hold more moisture than cold air. Air which contains its maximum moisture content is said to be saturated.
When does condensation occur?
Condensation is chiefly a winter problem. The external air temperature is low, and the external walls and windows are cold. The usual sequence of events is as follows ;
1. Cold air enters the building.
2. The air is warmed up for the comfort of the occupants.
3. The warm air takes up moisture.
4. the warm moist air comes into contact with cold surfaces, walls and windows etc and is cooled below its dew point
5. condensation occurs as excess moisture is released.
Walls in kitchens and bathrooms (where moisture levels are usually highest) solid external walls, cold bridges such as concrete lintels set in cavity walls are commonly the areas in which condensation points for damp air.
Sources of moisture
- Paraffin and unventilated gas heaters.
- Clothes washing and drying
- Baths, dish washing, etc
Health concerns associated with condensation and damp
Asthma is heightened due to condensation, moisture, humidity, and water intrusion, which all contribute to indoor moisture. Mould infestation is a major trigger for asthma. Aside asthma, other health concerns of mould are infections, allergenic or immunological illness, and non allergic illness. Asthma is also triggered by the sensitization of dust mites accruing humid, wet regions of a structure. Another health effect associated with structural dampness is the presence of bacteria in an indoor environment. Bacteria requires water to grow and multiply. Bacteria is a source for the transmission of diseases, therefore putting occupants’ health at risk by water intrusion into the indoor environment. Water removal and drying of wet building materials within 2 days will likely prevent mould and bacteria growth, therefore reducing occupants’ vulnerability to disease.
This could be especially detrimental to the elderly or the very young.
Effective treatment of condensation
PAM Positive Input Ventilation uses air displacement to ventilate a whole dwelling, thereby improving indoor air quality and stopping or preventing condensation problems from occurring. Predominantly designed for installation in existing properties.
A single fan unit mounted in the roof space (for central location for flats) supplies fresh, filtered air into the dwelling via a central hallway or landing. This creates a slight positive air pressure which forces stale, vapour-laden air out via fortuitous air gaps or through humidity sensitive window vents.
The PAM PIV Loft Unit comprises a fan with connector duct and ceiling diffuser. The fan runs continuously, unless the loft temperature exceeds 25°C when the unit will switch off. Above this temperature the hot incoming air would be uncomfortable for the occupants and the risks of condensation are somewhat reduced. When the temperature falls below 25°C, the unit will automatically switch itself back on. At temperatures between 19°C and 25°C the unit operates in heat recovery mode, harnessing the benefits of solar gains whereby the air in the loft is warmer than outside air.
The ceiling diffuser has been aerodynamically designed to direct incoming air along the ceiling (coanda effect) where it mixes with warm, buoyant air before re-circulating downwards, thereby ensuring a more even thermal gradient between the floor and ceiling.
This image illustrates an example of how the unit pushes positive air pressure throughout a dwelling, therefore eliminating the condensation problem.