Lawrence Berkeley National Laboratory released the research report on the costs and benefits of building commissioning (Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse Gas Emissions, Mills 2004) in 2004, and it was updated in 2009 (Mills, 2009). These two research reports have been widely cited and have played a decisive role in promoting building commissioning in the United States.
In 2018, after a lapse of nine years, Lawrence Berkeley National Laboratory, in cooperation with The Building Commissioning Association (BCxA), again updated the study. The survey’s sample size of the research work is 839 (101 for New Construction and 738 for Existing Building) public buildings of various types, an increase of nearly 50% compared with the sample size in 2009, with a total construction area of 274.16 million square ft, covering 31 states in the United States (all climate zones). Some preliminary results are summarized as follows:
(1) Commissioning of New Construction (NCCx)
The median commissioning cost is $0.82 per sq.ft, with a typical range of $0.40 per sq.ft to $1.36 per sq.ft. The larger the building area (types of buildings affect the cost as well), the lower the average cost per sq.ft. Compared with the median of $1.16 per sq.ft in 2009, the commissioning cost per sq.ft showed a downward trend.
Commissioning costs accounted for the proportion of project construction costs, and the median fell from 0.57% in 2009 to 0.25%.
For more than 90% of projects, building commissioning starts from the design phase.
NCCx projects usually do not include energy-saving assessments. Only 6% of the projects participating in the survey include scope item to
evaluate energy savings.
FIRST COST SAVINGS (top five):
1) Project on schedule, problems detected and corrected earlier (90%)
2) Occupied on schedule (79%)
3) Improvements to system design, equipment sized correctly (77%)
4) Improve construction team coordination, reduce disagreements (74%)
5) Building occupied sooner, call-backs reduced, TAB costs reduced (62%)
ONGOING (RECURRING) IMPROVEMENTS (top five):
1) Thermal Comfort (95%)
2) Maintenance (90%)
3) Improved Operation and Management (87%)
4) Training; Education (87%)
5) Indoor Air Quality (72%)
(2) Commissioning of Existing Buildings (EBCx)
The median energy-saving rate is 6%, with a typical range of 3% to 10%. The simple investment recovery period is 2.2 years, and the typical interval is 1 to 4 years. The median project cost is $0.26 per sq.ft, with a typical range of $0.15 per sq.ft to $0.56 per sq.ft.
The top five reasons for owners to implement existing building commissioning:
1) Obtain energy savings (100%)
2) Ensure system performance (91%)
3) Ensure or improve thermal comfort (78%)
4) Ensure adequate indoor air quality (46%)
5) Qualify for rebate, financing, or other services (38%)
The first five common commissioning strategies:
1) Scheduling (31.9%)
2) Operations & Control (22.3%)
3) Implement Advanced Reset (21.8%)
4) Modify Setpoint (10.5%)
5) Modify Sequence of Operations (8.8%)