Case Study - Sketch Plan - D: Scheme Design
General observations
During this stage the design team are firming up their proposed design solution in terms of drawings, specifications and a detailed cost plan in the form of elemental cost targets prepared in accordance with the principles, instructions and definitions of the standard form of cost analysis. The reader should consult Chapter 10, especially pages 108 to 133 of the textbook, which describes the process of preparing the detailed cost plan.
It is essential that good communications are maintained between the various members of the design team in order to ensure that the optimal solution is achieved to the client's brief.
In order to produce the detailed cost plan the BCIS has again been interrogated by the authors and three detailed cost analyses have been found from which the cost plan has been prepared (cost analyses) which again have been adjusted for market conditions (tender price index) and location (location index)
The procurement issues have already been addressed but observation of the project details shows how the specification including the services has been developed to ensure the life cycle of the various components are in balance and that the services minimise energy consumption during the building's use.
Concerning buildability issues the design team have attempted to produce, in the arrangement of the building, the most efficient geometrical arrangement by measuring the efficiency of the enclosed space by the use of Floor/Wall and POP ratios as described together with other considerations in Chapter 7 of the textbook and reflecting this within the scheme design as indicated on the drawings and additional design information.
Additionally a design solution has been developed which takes account of the seasonal weather variations and does not commit any unnecessarily over-sized lifting equipment and scaffolding and the like by ensuring that there are no excessive isolated heavy units to be lifted or any isolated large spans required.
The solution has also attempted to create a construction programme whch facilitates minimum disruption between the main contractor and the service subcontractors by facilitating continuous service installation work. These various considerations of buildability issues mean that a construction programme can be established which facilitates the most optimal construction time and cost.
During this stage detailed solutions are being developed for the various elements for example the substructure element where a site investigation report together with boreholes have been commissioned to allow the development of the technical solution together with the establishment of the cost target for this key element.
You are now invited to look at the cost model showing the detailed cost plan in the form of the various cost targets together with the accompanying specifications, that have been established for the various elements.
Note how the element unit quantities have been established for the various elements and how the various cost targets have been derived by allocating overall unit rates to each relevant element unit quantity. Also look at the cost target for the Preliminaries element which is essentially made up of fixed and time related costs rather than measurable quantities of work that can be ascertained from the drawings.