Commercial control for public building decarbonisation works

We supported a contractor delivering decarbonisation works across two public buildings. Proposed cost plans totalled approximately £4.5 million, with heating upgrades, plant replacement and associated building works requiring careful coordination. Our quantity surveying work examined package allowances, preliminary costs and forecast exposure, helping the project team understand the commercial effect of developing scope and changes to the delivery period.

Background

The schemes involved replacing and adapting heating infrastructure in existing buildings, with new plant, acoustic treatment and associated electrical and building works. Design development, power-supply arrangements and interfaces between specialist packages all affected the scope to be procured and the cost of delivery.

The project team needed to distinguish defined work from unresolved allowances, while keeping the contractor’s own resources and the specialist subcontractor’s preliminaries aligned. Changes to the programme could increase management and site costs even where the physical installation scope remained similar.

Our approach

We worked through the cost plans by package and cost heading. Heating infrastructure, plantroom works, design fees and acoustic enclosures were set out separately from contractor preliminaries, risk and provisional sums. This made it possible to question individual allowances and identify the information needed to refine them.

The review identified potential overlap between the specialist subcontractor’s preliminaries and the main contractor’s provision. Design-development and construction-risk allowances were also identified for further breakdown, rather than left as unexplained lump sums. Items dependent on existing-building information, including support steelwork and alterations to services, remained visible as specific uncertainties.

We examined the contractor’s preliminary costs against the resources and duration required. The reconciliation set out roles, allocation percentages, weekly rates and periods, alongside the costs of site facilities and other project support. Different duration and resource assumptions were modelled to show how the forecast would change.

That exercise produced a target forecast and alternative scenarios. The difference between the scenarios mattered because a single preliminary-cost total could conceal the effect of delayed design, longer attendance or changes to the level of management support. The model allowed the commercial team to examine those drivers directly.

Acoustic enclosure options were reviewed separately, using the available quotations and the scope of associated work. Potential differences in price were identified as matters for commercial evaluation, with the surrounding design and programme requirements still needing to be considered. They were not treated as an unconditional saving.

The supporting project records brought together procurement recommendations, payment applications, variation tracking, cost reporting and programme reviews. This provided a working commercial record across both schemes, with cost and scope issues capable of being followed through the delivery period.

Outcome

The client had a more detailed basis for reviewing its forecast, questioning package allowances and planning the resources needed to complete the work. The preliminary-cost reconciliation made the effect of alternative delivery assumptions visible, while the cost plans identified the areas where further design or subcontractor information was needed.

Our contribution was practical commercial control: making the components of the forecast clear enough for the project team to challenge and manage them as the schemes developed.