Exchange Cost Model - Variation Estimate

Project Stage

Stage	Name	Valid
0	Portfolio requirements
1	Conception of need
2	Outline feasibility
3	Substantive feasibility
4	Outline conceptual design
5	Full conceptual design
6	Coordinated design and procurement
7	Production information
8	Construction
9	Operation and maintenance
10	Disposal

Overview

Please ensure that you have read the process mapping document 'pm_cost_modelling' before proceeding with this exchange requirement.

The scope of this exchange requirement is cost modelling stage 5 - Actual Cost Decomposition. It is applicable at any stage of a project where work has been done or materials provided for which a variation (change) in cost may be appropriate as a result of a change in specification of materials or services or a change in the extent of their provision.

The exchange requirement is based on the premise that either:
It is based on the premise that either:

• A Building Information Model is in use in which cost values are assigned to objects and grouped into cost items and that it is possible to determine two states of objects and their costs enabling a cost prior to variation and a cost subsequent to variation to be determined (and consequently a variation cost though the subtraction of pe-variation cost from post variation cost OR
• It is possible to identify objects within a cost schedule that are subject to variation and to create a modified version of the cost schedule post variation so that variation costs can be identified as above.
  Thus, a variation estimate can actually be seen as (potentially) three separate schedules:

1. The schedule of items that are subject to variation
2. The schedule of items subsequent to variation
3. The schedule of changes

The extent of the information used for the variation estimate is a subset of the information defined for the quotation estimate (and therefore uses the same definition as that shown in the exchange requirement 'er_exchange_cost_model(quotation_estimate)' ). The sum of the contents of the models used for variation estimates over the project when added to the initial quotation estimate should be the same as the complete model used for the final account (see below).

Depending on contractual agreements, variation estimates may include additional factors that take into account changes in price between the time of quotation and the time of purchase. These are incorporated as additional cost values associated with objects and within cost items.

Information Requirements

Context	Information Needed	MAN	REC	OPT	Actor Supplying	Functional Part
Cost Items and Schedule	Cost items and cost schedule that are included within a variation estimate are the same as those that are included within a quotation estimate. The extent of cost items included is a subset of the total and these are the items that are subject to variation. Cost items should be defined prior to variation, post variation and as the actual variation (change). These cost items should be incorporated into the relevant cost schedule. The following amendments apply to the exchange requirement er_exchange_cost_model(quotation estimate) when applying its content to a variation estimate.				Contractor	er_exchange_cost_model(quotation_estimate)
Cost Groups (Cost)	Additional cost values may be associated to the post variation and variation schedules to account for cost increases over time. The method of incorporating such additional values is identified in detail within the functional part fp_model_cost_item				Contractor	fp_associate_cost
Cost Schedule	There is no value currently established as a predefined type of cost schedule for a 'variation estimate'. Therefore, for each schedule used to determine the variation, the schedule type should be set to 'USERDEFINED' and the object type set to 'VARIATION'.				Contractor	fp_model_cost_schedule

Results

Result type (FP/ ER/ Document/ PSet/ Specification etc.)	Information Provided	MAN	REC	OPT	Actor Receiving	Result Identifier
Model	Model of actual project as completed with elements collected together into groups with actual and final account cost values associated and grouped into cost items.				Cost Modelling
Schedule	A schedule or schedules with prior to variation, post variation and change cost items broken down into line items, cost groups and cost parts.				Cost Modelling