Air- Conditioning effects on timber floors
The common usage of air-conditioning in modern dwellings begs the
question of whether its performance has a significant impact on the
relative functionality and performance of timber flooring. Within a
dwelling, there are many things that also influence the relative humidity
in a comfortable living environment. Furnishings, such as curtains and
rugs also tend to moderate the internal environment by not only
reducing heat gain in the floor, but also absorbing and emitting moisture
depending on the humidity, similar to the timber floor. It is also
important to consider that in conditions that we feel most comfortable,
the floor will also perform at its best. More extreme use of cooling
systems for extended periods inside the dwelling can cause abnormal
conditions and have a detrimental effect on floors, so it is certainly an
aspect that needs to be considered. The relative humidity is a measure
of how dry the air is. Therefore, the lower the value, the drier the air.
When the humidity is low, moisture in timber flooring moves into the air
causing the moisture content of the flooring to reduce. A reduction in
timber flooring moisture content is accompanied by shrinkage.
Conversely, an increase in relative humidity will cause moisture uptake
by a floor and expansion.
The response of different products to changes in relative humidity
To a degree all timber based flooring products will change their
moisture content and dimensions in response to changing relative
humidity. The degree of movement (shrinkage or swelling) will occur at
varying rates based on the primary elements of specified products, this
being whether they’re solid timber, bamboo, engineered or laminate.
With changing humidity, solid timber floors have greater movement in
board width than the other categories but minimal change in length. In
strand woven bamboo, the movement characteristics are similar but a
little less. Engineered flooring with a cross laminated construction are
generally designed to reduce the amount of expansion or shrinkage in
board width compared to solid timber, but this introduces some
movement in board length.
The effects of different air-conditioning systems
The two common types of air-conditioning used in domestic housing
are refrigerative air-conditioning (often referred to reverse cycle, ducted
or split system) and evaporative air-conditioning. Refrigerative air
conditioners work well in warmer humid conditions and therefore

humidities are often higher outside when lower humidity inside the
dwelling can be beneficial. Evaporative air-conditioning works well in
hot dry conditions and therefore some moisture added to a dry internal
environment can also be of benefit. With evaporative air-conditioning it
is a good principle to leave some windows partly open so that the fresh
air entering the dwelling can expel the warmer air present.
In essence, the key is to maintain a balance with both systems to
provide a comfortable internal living environment. Also being able to
identify the certain time of the day in which cooling through air
conditioning is beneficial to the internal elements of the dwelling and
the reliance of natural ventilation for the protection against
unnecessarily drying out or creating overly moist environments for the
timber floors. The unpredictable nature of Australia’s climate, in which
there can be extended periods of humidity, as well as longer spells of
dryness in the air, means that the individual needs to be incredibly
vigilant in maintaining a cool, indoor environment within their dwelling to
ensure their timber flooring can pertain to the entirety of its life cycle.

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