1:5:200

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In the construction industry, the 1:5:200 rule (or 1:5:200 ratio) is a rule of thumb that states that the initial construction costs of a building, the operating costs over 20 years, and the business staffing costs over 20 years will be in the ratio 1:5:200. The rule originated in the introduction to a paper by Evans et al. (see Further reading.). Sometimes the ratios are given as 1:10:200. The figures are averages and broad generalizations, since construction costs will vary with land costs, building type, and location, and staffing costs will vary with business sector and local economy.[1][2]

Hughes et al., of the University of Reading School of Construction Management and Engineering, observed that the "Evans ratio" is merely a passing remark in the paper's introduction (talking of "commercial office buildings" and stating that "similar ratios might well apply in other types of building") forming part of a pitch that the proportion of a company's expenditure on a building that is spent directly on the building itself (rather than upon staffing it) is around 3%, and that no data are given to support the ratio and no defence of it is given in the remainder of the paper. In attempting to determine this ratio afresh, from published data on real buildings, they found it impossible to reproduce the 1:5:200 ratio, in part because the data and methodology employed by Evans et al. were not published and in part because the definitions employed in the original paper could not be applied. The ratios that they determined were different by orders of magnitude from the 1:5:200 ratio, being approximately 1:0.4:12. They observed that "everyone else who deals with real numbers" pitches the percentage somewhere between 10% and 30%, and that their data support 12%.[3]

They note (as does Clements-Croome) that the three costs for every individual building are affected by a plethora of factors, yielding a wide variation in ratios. They suggest that "[p]erhaps the original 1:5:200 ratio was simply meant to be a statement to focus clients' attention" on the importance of considering the higher staffing costs of a building relative to its operating and construction costs, and to encourage people to not be too concerned with higher initial build costs to improve build quality and reduce later lifetime costs. They state that if this is so "then subsequent users of the ratio have misused it", and that the frequency of use of the ratio is not problematic, but that the authority and gravitas that are assigned to it is. They conclude that "perhaps the most worrying feature of this whole discussion is how this passing introductory remark in the paper by Evans et al. has gained the status of a finding from research carried out by the Royal Academy of Engineering, which it most certainly is not!".[3]

[edit] References

  1. ^ Gavin Tunstall (2006). Managing the Building Design Process. Elsevier, 113. ISBN 0750667915. 
  2. ^ Derek Clements-Croome (2004). Intelligent Buildings: Design, Management And Operation. Thomas Telford, 342. ISBN 0727732668. 
  3. ^ a b Will Hughes, Debbie Ancell, Stephen Gruneberg, and Luke Hirst (2004). "Exposing the myth of the 1:5:200 ratio relating initial cost, maintenance and staffing costs of office buildings" (PDF). F. Khoswowshahi Procs 20th Annual ARCOM Conference, 1–3 September 2004, Edinburgh, UK I: 373–382, Reading: ARCOM. 

[edit] Further reading

  • Raymond Evans, Rochard Haryott, Norman Haste, and Alan Jones (2004). "The long-term costs of owning and using buildings", in Sebastian Macmillan: Designing Better Buildings: Quality and Value in the Built Environment. Taylor & Francis, 42–50. ISBN 0415315255. 

[edit] See also