General: Performance Specifications tell a manufacturer, vendor, supplier or provider: What is considered to be an acceptable product? And How will the product's acceptability be judged ? In other words performance specifications state requirements in terms of the results to be achieved and provide criteria for verifying the compliance. Such specifications define the functional requirements for the product, the environment in which it must operate, and the interface and interchangeability requirements. Performance specifications, however, do not state means or methods for achieving the results. It allows the supplier with freedom to not only choose but improvise materials and methods.
Systems specifiers like a designer deal with a product or system only occasionally and do not get frequent feedback. Whereas a system provider (such as the supplier, manufacturer, fabricator or installer) is consistently involved in supply field, and receives feedback from diverse sources. System suppliers as a result has better understanding and capacity to improvise the product. A system specifier may specify a technologically adequate system, but a system provider offers a technologically superior and economically most appropriate item.
A designer as a system specifier must work in close collaboration with the markets (represented as the supplier, manufacturer, fabricator or installer, etc.). To specify performance, ideally a system specifier and the parties capable of submitting the proposal or bid, both must have a consensus as to what the requirements are. But this type of neutral interaction is not possible or desirable in Government deals. So it is desired that requirements of performance are specified quantitatively rather than qualitatively. Qualitative data can provide varying interpretations and cause misunderstandings, but quantitative data is easily verifiable.
Performance and Verification: Any condition, characteristic, or capability that must be achieved, and is essential for item to perform in the perceived environment must be plausible and verifiable. For example, if a building is required to withstand certain measure of an earthquake, then methods how to verify this must be stated. Verification process is accompanied by definition of 'the extent of contractor or vendor's participation and their liability for providing corrective solution’. Warranties offered by the vendor can to some extent substitute the performance and verification requirements. However, very often warranties of the vendors are restricted to their own supplies. The warranties are also conceived like a risk management system for compensating a fault with something 'equivalent' or money, but not the for the affectations that occur in adjacent areas or systems.
In comparison to item or work specifications, performance specifications require fewer references, except for standard tests, interface drawings, etc. Due to the absence of procedures, performance specifications are less dependent.
Restrictions in Performance Specifications: Performance specifications must not limit a provider to specific materials, processes (including quality of man power or equipments), parts, etc. However, one can prohibit certain materials, processes, or parts when authorities have declared quality, reliability, or safety concerns such materials, technics or processes, as for example environmentally harmful technologies. Upper and/or lower performance characteristics can only be stated as requirements, but not as goals or best efforts.
Writing performance specifications: A System specification writer must know: ‘Which requirements are absolute or threshold requirements? Definitions of such thresholds. All constraints governing operations or use through natural and induced environments, interface with other systems, operator and maintenance person's limitations, must be declared’‘.
Performance Specifications for Structural, Architectural and Interior Design jobs: Such jobs consist mainly of industrially produced and standard components, but their composition (fabrication, installation or siting) is a unique phenomenon. Performance specifications at parts or components level are not very difficult to implement. However, adopting a performance specification strategy for large complex systems, or whole projects is a very difficult proposition. Design professionals can overcome this problem by consciously moving towards self-sufficient systems like plug-in modules, rather then excessively customised products that remain one-time efforts. Performance specifications at lower levels such as for replaceable components and spares, should include essentials for interchangeability and interoperability.
Strategies for Creating Performance Specifications: It is very difficult to conceive a fresh set of exclusive performance specifications. But one can gradually and consciously reformat the traditional specifications with inclusion of performance parameters for standard parts and components.
Resources for Performance Specifications: Many resources are available to form performance specifications, such as: Government departments and large corporate groups which prepare indexed descriptions of commercial items for frequently or routinely required products. Such performance oriented descriptions are available in a public domain through their purchase bids. Trade associations, commercial organizations, or technical societies often develop coordinated standard specifications, for the warranted performance of items produced by their members. Government Departments design and publish Model Specifications for use by their own sub departments and other agencies. Performance specifications of well-organized departments like defense, telecommunications, etc. can be used for further understanding of the methodology. Market analysis as available in technical journals can show the ranges of performance that are currently possible. Market analysis also show the technologies involved and available alternatives.
Standard Performance Specifications: Standard performance specifications are intended to facilitate standardization and interchangeability of common equipment. Standard performance specifications specify product characteristics, dimensions, matters relating to form, fit, and functions.