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  • PublisherCIBSE
  • Product CodeRR4/94
  • Number of pages81
  • Publication DateOct 1994
  • ISBN

RR4 (archived): Engineering design calculations and use of margins (pdf) (1994)

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RR4 (archived): Engineering design calculations and use of margins (pdf) (1994)

WARNING: ARCHIVED TITLE
In August 2018, CIBSE's Knowledge Programme Sub-Committee decided that this title was seriously out of date and should be withdrawn from use and be archived. It is being made available for archive use only and the file is now named and watermarked accordingly. 

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This 1994 report discusses the use of design margins in building services engineering design calculation based on primary research of then current industry practice covering both the magnitude of margins used in practice and the justifications given for their use. The research also looks in detail at the various issues connected with over-engineering in the building services industry, and in construction in general, such as over-design, over-specification and over-sizing, defines these and derives a model showing these various issues in the context of the overall building process. It is suggested that additive design margins can contribute to over-engineering, and the research identifies the specific areas to which design margins could contribute and also takes an overview of other industry initiatives to combat the problem such as value engineering and feedback. Detailed definitions of various kinds of margins are given, together with a review of the range of margins used in practice. Nine different types of design margins are identified and recommendations made for action to reduce the use of unnecessary margins, with specific action to be taken by both client and designer.
 
Acknowledgements
Authors: Gay Lawrence-Race & Mike Smith (BSRIA)