You own and occupy it
The simplest case. You pay the bill and you own the roof, so the decision is yours alone.
You can act on anything: the roof, the plant, the fabric and the way the building is run. Nothing needs a third party to agree to it, and nothing needs a lease clause read first.
You pay the bill, so every unit saved is yours. That makes payback the whole question, and it is the only situation where the person funding the work and the person seeing the saving are the same.
The ones this building type tends to suit. Each is still read against your building before anything is proposed, and a measure that does not suit yours will say so.
The charges on the bill that need no spending at all: agreed capacity, network band, levy relief and the VAT rate. They get skipped because attention goes straight to the roof.
Order the work by payback and by the age of what is already there, and take the free findings on the bill first. The report gives you the cost, the saving and the payback for each measure so the sequence is yours to set.
Read your own buildings
Add a building and its energy data, and every measure is read against it. It costs nothing and nobody contacts you unless you ask.