NEC4 - Option A, X15 included. Value Engineering? Changing to Scope? Compensation Event?

We are in the following situation under NEC4 ECC Option A (secondary Option X15 incorporated). Contractor design.

The Contractor gets one tender from a Subcontractor that could complete some of the works by an alternative method at 25% cheaper than the quoted price, this alternative method would meet the performance specification for these works in the Scope.

I would assume the Contractor can change the method shown in the Accepted Programme, as long as the new method meets the specification stated in the Scope.

My question is, does this imply a change to the Scope? Does the Project Manager need to instruct a change to the Scope? - If the Contractor submits their new design for acceptance, this doesn’t mean the Project Manager needs to instruct a change in the Scope, does it?

What are the clauses that clarify this in the Contract, what clauses should be followed to resolve this scenario? I’m confused.

Many thanks for your help

Yes, the Contractor can change the method shown on the Accepted Programme for the circumstances you describe. In doing so the Contractor may need to resubmit the Activity Schedule in accordance with clause 55.3 (the value of the Activity Schedule being unamended).

The Contractor may also be required to submit the new design in accordance with clause 21 depending upon the requirements of the Scope. From a design perspective, the Contractor’s obligation is to design the works stated in the Scope (see 21.1). Provided the design complies with the Scope and the law then it should be accepted.

No, the change in design does not require a change in Scope (provided the design complies with the Scope) and the PM would not need to instruct a change. If the revised design does not comply with the Scope then the PM can reject (not accept) it.