Although studies that quantify the actual life span of buildings are lacking, the reasons for demolition of buildings are quite well documented. Studies conducted in Australia (Kapambwe, Ximenes, F, Vinden, & Keenan, 2009) and the US (Athena Institute, 2004) indicate that less than 10% of buildings are demolished due to reaching the end of their structural service life. Studies show that it is usually other factors that determine the building’s service life, such as:
- Redevelopment for economic reasons (surrounding land has increased in value to the extent that it is more profitable to increase the density or use of the building)
- Redevelopment for aesthetic reasons (the building is no longer in fashion)
- Fire or other disaster
For best practice, building design should attempt to match the structural durability with the redevelopment potential of the building. For this reason at Cerclos, our estimated design life often differs from industry perceptions of building life span. For example, architects in Australia tend to expect detached residential buildings to last over 60 years (Kapambwe, Ximenes, F, Vinden, & Keenan, 2009).
In eTool, we use the following characteristics when estimating design life:
- Quality of the construction – the better the quality of construction, the longer the structure will last.
- Number of people who own the structure – the more people who share ownership of the structure, the more difficult it is to gain approval to demolish it.
- Redevelopment rate of the area the structure is located in – if the structure is located in an area with lots of redevelopment happening (i.e. CBD vs rural), it is more likely it will be demolished for redevelopment.
- Service life of the structure’s materials as a whole – the structure will technically last longer if the materials selected are more durable.
*You can get more information about each of these factors by clicking on the ‘(i)’ icon next to the item.
Depending on what these factors are, the life of the structure may be prematurely shortened or last longer than anticipated.
In eTool, we have a built in ‘Service Life Calculator’ (in the ‘Details’ tab of your design) that will give you a ‘Predicted Service Life’ depending on what is input into the above fields. ‘Predicted Service Life’ is usually lower than what is put under ‘Structural Service Life Limit’.
Design Quality = quality of the construction
Ownership = number of people who own the structure
Structural Service Life Limit = service life of the structure materials
Suburb Redevelopment Potential = redevelopment rate of the area
For situations where you have to limit your study to a specific period such as for some rating systems like BREEAM, LEED or Green Star (60 year study requirement), activate the ‘User Defined Predicted Service Life’ button. This enables you to manually override the calculated years.
As best practice, we advise users to use this manual override and leave the other 4 factors at what they should be rather than tweaking the combination of factors to generate the required Predicted Service Life outcome.