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This suggests the cost of level 3 and level 4 buildings will increase by 2.5%
and 3.75% respectively, since they would need to be 20% and 30% stronger,
respectively.
Figure 4.1
Additional building cost at various design wind speeds
Source: Mullins Consulting 2006: page 8
The third piece of evidence is from a New Zealand study that examined the
costs and benefits to changes to earthquake and wind loading design
standards (Branz, 2006). Figure 4.2 summarises the results of the various
cost studies that were conducted. Importantly, these are based on a sample of
buildings that were notionally re-designed for compliance with new standards.
Note that the cost/load relationships are similar for wind and earthquakes. For
the load increases that are relevant to this study, 20%-30%, the cost
increases are in the range 0.5%-1%.
The sample of public buildings - comprising one hospital, two schools, and
three social and cultural centres – returned estimates of cost increases of
0.5%, 1.5% and 2%, for load increases of 20%, 40% and 80% respectively.
ABCB Regulation Impact Statement (RIS 2007-03)
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