Assuming building staff are adequately trained to maintain comfort in the space but not skilled at hvac design or not mandated to uncover, diagnose, and fix hidden operating problems.
The original design of most buildings involves many assumptions about occupancy, internal heat gains, lighting loads, building envelope performance, etc. As a result, design engineers make conservative assumptions and design for extreme conditions. Little thought is put into part-load efficiency.
Building commissioning focuses on occupancy comfort with little regard for energy consumption. Also, commissioning takes place at the end of a project, and often is neglected due to project delays, cost overruns, reduced budgets, etc.
There have been many significant changes to the building that further reduce the effectiveness of the original design. These changes include:
|•||Additions and renovations.|
|•||Adjustments to dampers and valves that result in unbalanced air and water systems.|
|•||Increased fuel costs.|
We recommend implementing Continuous CommissioningSM in the building to improve occupancy comfort, reduce utility costs and upgrade the skills of maintenance staff.
Continuous CommissioningSM is implemented in two phases:
Phase 1: Project Development. Most of Phase 1 has already been completed as part of this ManagingEnergy.com report.
Phase 2: Implementation and Verification. This phase includes the following steps:
Step 1 – Develop plan and form project team.
Step 2 – Develop performance baseline.
Step 3 – Conduct system measurements and develop processed measures
Step 4 – Implement measures.
Step 5 – Document comfort improvements and energy savings.
Step 6 – Keep the commissioning continuous.
Further details can be found in the Continuous Commissioning Guidebook.
So costs are incurred with an intensive process in the first year, followed by a much smaller recurring expense in subsequent years to sustain the savings.
Further details can be found in the Continuous Commissioning Guidebook, which is available for free download from Texas A&M University.
Aside from utility savings, Continuous CommissioningSM will improve occupant comfort and increase the skills of building staff.
Issues and Concerns
Continuous Commissioning is a service marked term used by the US Dept Of Energy to describe a commissioning process outlined in Continuous Commissioning Guidebook for Federal Energy Managers.
This is highly speculative and can only be based on research, since there is no way to know what recommissioning will uncover in any particular building.
FEMP, Texas A&M study found that recommissioning generates savings correlating to a simple payback of 8.5 months. However many of their research buildings relied on purchased steam or chilled water, which showed much better savings than buildings with standard utility services. To be more conservative, use a 2.5-year simple payback to work back to savings. Also note that CC is more successful in larger buildings and energy-intensive buildings, less effective in small buildings.
FEMP, Texas A&M study found that recommissioning (1 time) costs $0.27 per sq.ft. and generates savings correlating to a simple payback of 8.5 months. Use $0.30 per sq.ft. to allow for inflation and currency differences.
Additional Annual Costs (Other than Energy):
Annual recurring costs equal to 15% of initial recommissioning project.