Commissioning: Design-Phase Commissioning By The Numbers
November 1, 2008
Better late than never, but cheaper early than late.
Last month, I presented benefits associated with beginning the commissioning process during the design phase. This month, I would like to present some numbers that might help quantify the value to building owners of starting early.
I noticed recently that in full-scale commissioning projects - i.e., those which start early in design and extend through the first year of occupancy - approximately 25% of the total commissioning fee is expended during the design phase. I then investigated how the remainder of the fee is typically split between the other phases of a project, specifically the Early Construction Phase, the Testing and Training Phase (late construction), and the Post-Occupancy Phase.
Table 1 illustrates the distribution of total fees for two projects. Project 1 is a large project ($100 million) and Project 2 is a medium-sized project ($25 million). In general, for similar scopes of commissioning services, this breakdown is very consistent.
Table 2 outline what the commissioning fees for the same two projects would be if com-missioning were introduced soon after the construction contract was awarded without a commissioning specification. The total fee would be reduced by 15%to 20%, but the owner would lose much of the benefit of commissioning design reviews and the docu-mentation and training planning process.
The fee reduction is not 25%, however, because a number of activities that are best performed in the Design Phase would still need to be performed in the Construction Phase under this scenario, such as developing a commissioning plan, becoming familiar with the design documents, etc.
What is the value to the owner of finding and addressing system performance issues during design instead of after equipment has been ordered, installed, and/or started up? What is the potential “extra” the contractors will want in order to add commissioning to their scope of work via change order? When one considers that commissioning fees typically range from 0.5% to 1.0% of total construction cost, saving 15% to 20% on commissioning fees equates to less than 0.2% of the total construction budget.
Similarly, Table 3 represents fees for the same projects if commissioning were introduced towards the end of construction.
The facility owner could realize 25% to 35% commissioning fee savings (or up to 0.35% of total construction) if he waited until the end of the project to start the commissioning process. However, what is the risk to the owner of contractor change orders or the discovery of major performance problems or schedule delays?
Owners need to make these cost/benefit decisions for themselves based on the unique set of circumstances surrounding each project. Perhaps the numbers presented here can be used as input to more objective decision making in the future. ES