Condensation in Properties

What is condensation?

Condensation can also be the result of complex interactions between the environment, building construction and occupant behaviour. Condensation may cause microbial growth, dampness, wood rot, corrosion, weakening of mortar and masonry walls, and energy penalties due to increased heat transfer

What causes condensation?

Condensation with buildings can be caused by several factors. These include:

Environmental conditions include external ambient temperature, humidity, and solar/radiant loads. These weather conditions (typically occurring in Melbourne between the months of May and August) can cause the façade glazing and framing system to cool.  During warmer months, external conditions required for generating condensation are much less frequent. The orientation of a façade may also affect these factors.

Operations within a property cause the humidity level to become elevated. These operations include:

  • High numbers of people within the apartments (respiration and/or perspiration), or
  • High amount of steam escaping from bathrooms (due to exhaust fans not being operated), or
  • Washing of clothes using hot/warm water without an exhaust fan, or
  • Traditional Dryers being used within apartments (see note below) or clothes drying generally, or
  • Cooking equipment, or
  • Heavy personal exercise within the apartment, or
  • Plants, pets, and fish tanks can also increase humidity levels, or
  • Poor maintenance of plant and equipment, or
  • Poor apartment ventilation -­‐ apartments are provided with ventilation (as required by the Building Code of Australia). Residents should use these devices
  • Any combination of the above factors.

Moisture generated within a property will remain in the space unless a window is opened, the air conditioning system is used in cooling mode or any of the exhaust air systems (range hood or bathroom exhaust fans) are used.

Indoor sources of water vapour in dwellings:

What can be done to minimise humidity in properties?

The following practices can be used by the residents to minimize humidity within the properties:

  • Ensure that exhaust systems are utilized for bathrooms and cooktops operations. Allow these to run for a period after use of the bathrooms or cooktop to assist in further exhausting moisture.
  • Using lids on cooking equipment and using the kettle near the range hood when boiling water.
  • Ventilating apartments can be effective to reduce apartment moisture levels. Even opening a balcony door or external window a small amount can assist in this regard.
  • The A/C units are effective in de-­‐humidifying the apartment. Run the A/C on cooling mode to de-humidify the apartment.
  • In extreme cases, utilize de-­‐humidification equipment. These systems are commercially available (and are commonly used in humid environments such as Hong Kong or Singapore) and can operate in conjunction with the heating systems within the apartment.
Confused between a window leak and condensation?
  • Often due to the timing of events, condensation, and water egress back into the building can be confused by residents. There are instruments available to confirm that the conditions exist to cause condensation, and investigation can be easily undertaken.
Who is responsible for the condensation?

The Victorian Building Commission has issued a Guide to Standards & Tolerances 2015, which acknowledges that “Condensate is a common problem in buildings, particularly in bathrooms and laundries, and can occur on windows”. “Where the requirements of the building code have been complied with, the responsibility for controlling condensation by maintaining adequate ventilation through the installation and use of exhaust fans or other means is the responsibility of the property owner or occupant”.

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