In a prior life, I was a project manager for a large corporation that engaged in performance contracting. At the time, performance contracting was in its infancy, but even then the keys to the success of a project were the role of trained operators and effective maintenance to ensure continued operation at or near the 'benchmarked' levels. Commissioning is the process by which facility operations personnel can be fully trained and receive a facility (project) that fully functions in accordance with its design intent.
Generally, an energy services company (ESCO) funds, installs, and, in some cases, operates and maintains the energy-efficient upgrade project. By contractual agreement, the owner then pays a portion of the annual energy cost savings to the ESCO. Since the ESCO has project risk to consider, projects that can most easily achieve the minimum levels of savings required to make the project risk acceptable are preferred. The ESCO may also be required to 'guarantee' the savings, adding to the cost of the contract. However, the ESCO's ability to acquire the lowest interest rates is driven in part by this 'guarantee' of energy savings.