Input specification vs output specification
Traditional specifications are ‘input specifications’. They are prescriptive, that is, they describe in detail the products, materials and work (the inputs) required by a contract. Typically, the development of the solution required by the contract is complete and no (or little) further development is required by the supplier. The specification is considered to be a ‘closed specification’.
Prescriptive input specifications give the client certainty about the end product when making investment decisions, but place a greater burden on them to ensure the product has been thoroughly considered, developed and described. They tend to be used where a very specific end result required.
Output specifications define only the outcomes (or outputs) that are required by the contract, that is, what it will enable the client to do. They are open specifications that do not attempt to address how those outputs might be achieved. For example, an output specification might require the provision of a space for teaching 30 primary pupils, but it would not specify the nature of the space, the types of doors and windows etc. The standard for what is required might be defined, for example, by reference to performance targets.
It is argued that output specifications can get the best value from the supply team by allowing them to adopt innovative solutions to the client's requirements and reduce whole-life costs rather than simply developing the client's pre-conceived solutions at the lowest price.
For more information see: Output-based specification.
[edit] Related articles on Designing Buildings Wiki
- Briefing documents.
- Feasibility studies.
- Final specifications.
- Insulation specification.
- Outline specification.
- Output specification
- Output-based specification.
- Performance specification.
- Prescriptive specification.
- Procurement.
- Service level specification.
- Specification.
- Tender documentation.
- Tender process.
Featured articles and news
RTPI leader to become new CIOB Chief Executive Officer
Dr Victoria Hills MRTPI, FICE to take over after Caroline Gumble’s departure.
Social and affordable housing, a long term plan for delivery
The “Delivering a Decade of Renewal for Social and Affordable Housing” strategy sets out future path.
A change to adoptive architecture
Effects of global weather warming on architectural detailing, material choice and human interaction.
The proposed publicly owned and backed subsidiary of Homes England, to facilitate new homes.
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.
UK Infrastructure: A 10 Year Strategy. In brief with reactions
With the National Infrastructure and Service Transformation Authority (NISTA).