Clearly, the cost of commissioning will depend on the scope of work, including the overall management, whilst the benefits will depend on the outcomes of the process and the persistence of any performance improvements that result.

Cost and Benefits of Commissioning

It is difficult to quantify the full costs of commissioning for a project given the variable circumstances that influence cost, and the fact that many costs can be hidden.

A US DoE sponsored study that meticulously compiled and standardised commissioning data from 224 commercial buildings should help encourage building developers and owners to invest more in commissioning management. The study included published and unpublished data from commissioning projects from the past 20 years and across 21 US states, and is the largest available collection of standardised information on commissioning and recommissioning.

The study concluded that commissioning is indeed cost-effective for both new and existing buildings over a range of building types and sizes, not only in terms of energy savings but also in savings from improved equipment lifetimes, reduced maintenance, fewer contractor call-backs, as well as other non-energy benefits.

While owners may assume good performance in new buildings, the numbers revealed that new buildings actually had three times more problems than existing facilities, as new buildings tend to have more complex, innovative systems, which can lead to problems if those systems are not properly designed, implemented, and operated. Also, more money (i.e. time and effort) is typically invested in commissioning new buildings, so it is not surprising that more deficiencies are found.

The projects in the study identified 3,500 different deficiencies among 85 existing building projects, and 3,305 deficiencies among 28 new construction projects.

Energy savings attributed to commissioning were six times higher in existing buildings than in new construction, perhaps evidence of the fact that existing-building commissioning is more strongly driven by energy savings, while commissioning of new construction is more motivated by non-energy objectives such as ensuring overall building performance meets the owner’s requirements including ensuring a healthy indoor environment.

Non-energy benefits contribute significantly to the cost-effectiveness of commissioning. These benefits include improved equipment lifetimes, reduced variation orders due to early detection of problems, prevention of premature equipment breakdown by timely correction of problems, reduced operation and maintenance costs, and improved indoor environment. When these often-overlooked benefits were taken into account, the cost-effectiveness of commissioning increased considerably, particularly among new buildings.

Careful evaluation of the costs and benefits proved commissioning to be one of the most cost-effective ways to improve energy efficiency in commercial buildings.

Existing buildings also stand to benefit from commissioning since buildings are essentially a collection of systems that can fall out of tune over time, and require periodic correction.

New Construction Cost and Benefits

New-building commissioning, costing 0.6% of total construction costs, took 4.8 years to pay back when only energy cost savings were considered. When non-energy impacts were factored in, those payback periods were considerably reduced, often to zero.

Cost and Benefits of Existing Building Commissioning

It was evident that few commercial buildings performed as intended, and in some cases over 50% energy savings were achieved by recommissioning. Among existing buildings, recommissioning yielded energy cost savings ranging from 7 to 29%, with a median savings of 15%, for quick payback times of 0.7 years.