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WHOLE LIFE COST (WLC)

The definition from the developing ISO Standard 15686 on service life planning is
"a tool to assist in assessing the cost performance of construction work, aimed at facilitating choices where there are alternative means of achieving the client's objectives and where those alternatives differ, not only in their initial costs but also in their subsequent operational costs."

  • WLC includes the systematic consideration of all relevant costs and revenues associated with the acquisition, use and maintenance and disposal of an asset.
  • Procurement costs can include: initial construction, purchase/lease, interest, fees
  • Recurring costs can include: rent, rates, cleaning, maintenance, repair, replacement/renewal, energy and utilities, dismantling or disposal, security and management.
  • Revenues can include: Sales of recycled materials, interest in asset and rental income.

Note: Life Cycle Cost (LCC) and Through Life Cost (TLC) are also terms used to describe the same process as WLC.

SERVICE LIFE
Life of a product or building element or whole building. May be

  • Technical (based on physical durability and reliability properties),
  • Economic (based on value and depreciation to owner) or
  • Obsolescence (based on factors other than time or use patterns e.g. fashion).

Note: In practice, Replacement Interval/Life is also used interchangeably with service life and the same distinctions apply.

WHOLE LIFE COSTING AND ENVIRONMENTAL IMPACT
WLC and LCA in the construction industry have developed separately in response to economic and environmental issues but the two tools have much in common, as shown in figure 1.

The key similarity is that both utilise data on:

  • quantities of materials used,
  • the service life the materials could or will be used for
  • the maintenance and operational implications of using the products
  • end of life proportions to recycling (and sale value) and disposal

The key differences are:

  • conventional whole life costs methods do not consider the process of making a product, they are concerned with the market cost. Life cycle assessment considers production.
  • WLC is usually discounted to present value over time, environmental impacts are not.

Figure 1: Commonality within the Building Cycle of issues relating to WLC and LCA

LCA
Stages in the Building Life Cycle
WLC
1. Extraction of raw materials  
2. Production of building components  
3. Construction

4. Use:

Repair
Maintenance
Replacement

5. Demolition
6. Recycling