A functional unit is a unit of measurement that represents the main use of a building or part of a building, for example per bed space, per house, per pupil place or per m² of retail area. It includes all associated circulation space.
Functional units are used at the earliest stages of a project, when there is little or no design information, to set a budget using the functional unit method. They are also useful for comparing the value for money of different schemes and for measuring performance across a client’s portfolio. Typical examples include:
- cost per bed space for hospitals, care homes and hotels;
- cost per pupil place for schools;
- cost per car parking space for multi storey car parks.
When using functional unit costs from historic data, the QS should check that the definition of the unit, the specification and the scope of what is included are consistent with the project being estimated.
Related terms: Functional Unit Method, Order of Cost Estimate, Benchmarking.
