Exchange Cost Model - Order of Magnitude

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 1 - Order of Magnitude.
That is, the cost model is based on factors related to the entire building

An example scenario for this stage is shown in the table below:

Within this exchange requirement, two specific sub-requirements are considered:

1. Building and site information can be harvested from specific objects that are defined for this purpose (the typical situation from a CAD or BIM system with a shape representation capability). In this case, building and site information to the required level of detail must be provided by a prior exchange requirement 'er_exchange_building_model (mass)'
2. Building and site information is created as part of the overall cost planning process in the absence of shape represented objects (the typical situation where CAD or BIM system shape representations are not available). In this case, there are no prior exchange requirements.

Within the information requirements section of this exchange requirement, it is assumed that information is created specifically for the cost model (namely, the situation described in item 2 above). Where information is available from a building model massing study, it should be interpreted according to the information requirements shown.

During this stage the information available is limited to the basic requirements. These include:

• a building is required
• it should be of a particular type or perform a particular function (several functions may be identified within a particular type)
• it should be located in a particular place and on a particular site (several alternative locations may be identified; each location should be dealt with individually)
• it has an estimated overall area and/or volume requirement OR it is related by a size factor to a similar previous project about which information is known
• there are factors that affect the 'order of magnitude' cost including (but not limited to) items such as
  • expected building configuration (e.g. multi-storey as opposed to single storey)
  • expected structural complexity based on ground conditions
  • expected level of servicing for operational and comfort purposes
  • accessibility of the location
  • labor resource availability

Particular information that is required to determine 'order of magnitude' cost includes:

• the name of the project (for identification purposes) and the units generally used throughout the project;
• the current stage of the project; whilst this is generally optional, it should be mandatory for this exchange requirement
• the location and expected area of a site on which a building is to be located (the shape representation of a site is not necessary for this Exchange Requirement)
• the building or buildings for which the cost is required (at least one building must be specified although the shape representation of a building is not necessary for this Exchange Requirement)
• the area, volume or size factor of the building
• values for factors that may affect the cost
  • factors may be applied to the building directly or individually determined
  • e.g. services costs may be on a volume or size factor basis
• classification of objects for collection into groups and assemblies for costing purposes

Information Requirements

Context	Information Needed	MAN	REC	OPT	Actor Supplying	Functional Part
Precursor	The provisions of the exchange requirement er_exchange_project must be satisfied. Project stage must be identified.				Building Design OR Cost Modelling	er_exchange_project
Precursor	The provisions of the exchange requirement er_exchange_building_model (mass) should be satisfied where the primary information about the building and site are to be harvested from a shape representation within a building model.				Building Design	er_exchange_building_model (mass)
Site (Generally)	Site information required to establish 'order of magnitude' cost.				Building Design OR Cost Modelling	fp_model_site
Site (Properties)	Site properties required to establish 'order of magnitude' cost.				Building Design OR Cost Modelling	fp_model_site
Building (Generally)	A building must be defined for the order of magnitude cost to be determined.				Building Design OR Cost Modelling	fp_model_building
Building (Quantities)	Building quantities required to establish 'order of magnitude' cost.				Building Design OR Cost Modelling	fp_define_quantity
Building (Properties)	Building properties required to establish 'order of magnitude' cost.				Building Design OR Cost Modelling	fp_model_building
Building (Cost)	Unit cost information should be assigned to the building to enable total cost to be determined.				Building Design OR Cost Modelling	fp_associate_cost
Cost Impact Factors	Various factors may be provided for the site and building to identify their expected impact on the order of magnitude cost in comparison with reference costs.				Building Design OR Cost Modelling	fp_define_quantity (count)
Cost Item (Measured)	A cost item should be defined for the measured item. At this stage, the cost measured cost item relates to the building				Cost Modelling	fp_model_cost_item
Cost Item (Ancillary)	Cost items that deal with specifically assigned costs such as preliminaries, external works, contingencies etc. should be individually identified and assigned to the 'head' object in the model to be used for costing. Typically, this is expected to be the project.				Cost Modelling	fp_model_cost_item
Cost Schedule	Costs and quantities may be collected together into cost items and ultimately into a cost schedule for further work.				Cost Modelling	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 proposed building with order of magnitude costs associated with appropriate objects.				Building Design Client
Schedule	A schedule of costs with cost items broken down into line items, cost groups and cost parts.				Building Design Client