ISO 15686 is the in development ISO standard dealing with service life planning. It is a decision process which addresses the development of the service life of a building component, building or other constructed work like a bridge or tunnel. Its approach is to ensure a proposed design life has a structured response in establishing its service life normally from a reference or estimated service life framework. Then in turn secure a life-cycle cost profile (or Whole-life cost when called for) whilst addressing environmental factors like life cycle assessment and service life care and end of life considerations including obsolescence and embodied energy recovery. Service life planning is increasingly being linked with sustainable development and wholelife value.
The objective of service life planning is to provide reasonable assurance that the estimated service life of a new building on a specific site, with planned maintenance, will be at least as long as the design. Service life planning facilitates the making of well-informed decisions regarding value engineering, cost planning, maintenance planning, and environmental impact. As service life cannot be estimated precisely, the objective requires the making of an appropriately reliable estimate of the service life of the building using available knowledge relating to the service life of each material, component, assembly, and system that is to be used in the building.
If the estimated service life of any of these is likely to be less than the design life of the building, a decision should be made as to whether maintenance, repair, or replacement could ensure that its essential functions could be adequately maintained. To assist with specification and design, and avoidance of obsolescence and waste, service life planning may include projections of the needs for, and timing of replacement and end of life recovery.
In Great Britain, the new British Standard BS ISO 15686-5:2008 Buildings and constructed assets. Service life planning is currently being launched (September 2008). The life cycle costing standard and the additional Standardized method of life cycle costing for construction (SMLCC) provide an in-depth guide to life cycle costing, an area of increasing importance. The BSI explains that "the UK building industry recognizes that life cycle costing (LCC) is necessary and important, but confusion exists about the best method to realise the economic and environmental benefits of such costing".
The design life of a component or product is the period of time during which the item is expected by its designers to work within its specified parameters; in other words, the life expectancy of the item. It is the length of time between placement into service of a single item and that item's onset of wearout.
The design life of components and products differs from the items' mean time between failures, (MTBF), in that MTBF is a measure of the rate of occurrence of random failures in time where these failures are not due to a wear-out mechanism. For example, the mean time between failure of a device may be 100,000 hours and the design-life is 20,000 hours. In this example, across the population of products, one failure will occur, on average, every 100,000 population operating hours. (100,000 units operating for 1 hour each = 100,000 population operating hours.) None of these units will ever approach reaching 100,000 operating hours as each one will fail due to wear-out and be replaced by a new unit. Aluminum electrolytic capacitors, fans, and batteries are classic examples of components that will fail due to wear-out well before they could individually achieve the operating time indicated by their individual MTBF.
Another use of the term design life deals with consumer products. Many products employ design life as one factor of their differentiation from competing products and components. A disposable camera is designed to withstand a short life, whilst an expensive single-lens reflex camera can be expected to have a design life measured in years or decades. (Clearly in this example there are other differentiators.)Life-cycle assessment
Life-cycle assessment (LCA, also known as life-cycle analysis, ecobalance, and cradle-to-grave analysis) is a technique to assess environmental impacts associated with all the stages of a product's life from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling. Designers use this process to help critique their products. LCAs can help avoid a narrow outlook on environmental concerns by:
Compiling an inventory of relevant energy and material inputs and environmental releases;
Evaluating the potential impacts associated with identified inputs and releases;
Interpreting the results to help make a more informed decision.List of International Organization for Standardization standards, 15000-15999
This is a list of published International Organization for Standardization (ISO) standards and other deliverables. For a complete and up-to-date list of all the ISO standards, see the ISO catalogue.The standards are protected by copyright and most of them must be purchased. However, about 300 of the standards produced by ISO and IEC's Joint Technical Committee 1 (JTC1) have been made freely and publicly available.Value engineering
Value engineering (VE) is a systematic method to improve the "value" of goods or products and services by using an examination of function. Value, as defined, is the ratio of function to cost. Value can therefore be manipulated by either improving the function or reducing the cost. It is a primary tenet of value engineering that basic functions be preserved and not be reduced as a consequence of pursuing value improvements.The reasoning behind value engineering is as follows: if marketers expect a product to become practically or stylistically obsolete within a specific length of time, they can design it to only last for that specific lifetime. The products could be built with higher-grade components, but with value engineering they are not because this would impose an unnecessary cost on the manufacturer, and to a limited extent also an increased cost on the purchaser. Value engineering will reduce these costs. A company will typically use the least expensive components that satisfy the product's lifetime projections.
Due to the very short life spans, however, which is often a result of this "value engineering technique", planned obsolescence has become associated with product deterioration and inferior quality. Vance Packard once claimed this practice gave engineering as a whole a bad name, as it directed creative engineering energies toward short-term market ends. Philosophers such as Herbert Marcuse and Jacque Fresco have also criticized the economic and societal implications of this model.
Value engineering is the structural and analytical process that seeks to achieve the value for money.
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