The overall economic and social situation
of recent years has accentuated the need for controlling
construction costs. Both owners and designers have become
very aware of the need to lower costs, which is today one
of the most important parameters of a building project.
The economics of a project can only be validly grasped if all factors influencing prices are accounted for in the earliest phases of the design work. Since each operation is specific, it must be evaluated both globally and in detail. The geographic location ,size typology, phasing over time or construction in several stages, the suitability of the work schedule and procedures, the possibility of using industrialized building processes and repetitiveness of the works must all be taken into consideration in preparing a realistic cost estimate.
The initial estimate must also be associated with a suitable costing methodology, because the cost estimate for a housing operation, for example, has little in common with that for a complex hospital program.
During the initial design concept/sketch design phases (and sometimes even before) the design directives considerably affect cost, even though the project is not yet sufficiently developed for any conventional costing based on quantity surveying.
By employing ratios per functional building sector in association with quantity surveying for the building envelope and specific works, it is possible to evaluate project cost very quickly, to identify elements penalizing the budget, and thus help the designer improve upon the design.
However, this method is not appropriate for major restructurization programs which require a maximum of quantity surveying work and anticipatory investigations relating to later phases of the design work.
Etablishing a precise and reliable
estimate for each of the design phases (building program,
design concept, schematic design, design development, contract
negotiations) is important but would appear insufficient.
The systematic analysis of modifications should explain
the changes that have occurred from one phase to another,
and should allow for action before presenting a project
whose budget has gone out of control.
A systematic analysis of the efficiency of floor areas and built volumes should also allow for the constructive criticism of any extra costs. Experience has shown that the economic aspect of an operation cannot be dissociated from its technical aspect. The critical analysis of a technical solution from an economic standpoint can only be valid if it is performed by an experienced building technician who himself is practiced in designing works.
An appraisal of the technical specifications, their level of requirements, the technical consistencies at interfaces and any missing items can only be validly performed by an specialist patrician. The consistency of the various approaches to an operation and its optimization as a whole are the key factors determining cost. Analytical methods based on comparing the ratios and typical scales of a project with reference data detect inconsistencies in “assembling” costs.
The final factor for cost control is tied to the organization of construction works contracts. How the building trades are organized, how the contractors are grouped together, how temporal and phasing constraints are accounted for and how site works methods are anticipated should be carefully and strategically thought trough to ensure the most efficient organization possible for building the project. And all the above are based on the systematic synthesis of prices, obtained as the result of having made many requests for bids, and on thorough command of the costing methods shared by all contractors.