Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua


Costing of Stormwater Treatment in New Zealand

COSTnz is a simple, easy to use computer model which allows users to compare the relative life-time costs of various stormwater management devices.

COSTnz was developed as part of a toolbox to help consultants, developers and decision-makers assess the relative performance and cost of different stormwater devices.

COSTnz is developed by Landcare Research using New Zealand data.

What is life cycle cost and why is it important? Life cycle costing is the sum of acquisition and ownership costs of an asset from design, manufacturing, usage and maintenance through to disposal. This helps to give us a better understanding of all the short and long term costs incurred as a result of constructing and maintaining stormwater devices.

Key features of COSTnz include:

  • It follows the Australian/New Zealand Standard 4536:1999 for life cycle costing
  • It combines acquisition, maintenance and decommissioning costs into a life cycle cost
  • It is a web-based application - just log-in and use
  • You can enter your own data, or use the handy default values
  • It delivers the total acquisition cost, maintenance cost, undiscounted life-cycle cost and discounted life-cycle cost as bar and pie charts
  • It allows you to compare and export cost data for different types of stormwater devices

Modules are available for ponds, rain gardens, wetlands, swales / filter strips, rain tanks, sand filters, infiltration trenches, plus a generic model for proprietary devices.

You could use COSTnz to:

  1. understand long-term investment requirements;
  2. make more cost-effective choices at the project scoping phase;
  3. improve design;
  4. negotiate financial contributions; and
  5. inform budgeting, reporting and auditing

Downloadable content & links