banner4_alpers_engineering.jpg

What is retro-commissioning?

Retro-Commissioning is the application of the commissioning process to an existing facility, which in most cases has never been commissioned.  The objective in retro-commissioning is to verify and document the performance of existing building systems in their present day operating conditions and compare that to the owner’s original intent or to a benchmark high performing building of similar type. This provides an evaluation of the performance of a building relative to similar buildings and the owner’s needs.

Retro-commissioning seeks to improve how building equipment and systems function together. Depending on the age of the building, it can often resolve problems that occurred during design or construction, or address problems that have cropped up throughout the building’s life. In all, retro-commissioning improves a building’s operations and maintenance (O&M) procedures to enhance overall building performance and extend its life and value.

What are the major steps in the typical retro-commissioning process?

Program Planning  Phase

  • Select the project based on energy utilization index
  • Set project objectives and obtain support from the owner and facilities team
  • Select a commissioning authority
  • Document the current operating requirements
  • Perform an initial site walk-through
  • Develop the retro-commissioning plan
  • Assemble the retro-commissioning team
  • Hold a project kick-off meeting with owner, the facilities staff, and all the teams members

Investigation Phase

  • Review facility documentation
  • Perform diagnostic monitoring on energy using equipment
  • Perform functional tests to verify performance
  • Owner performs simple repairs as found during testing
  • Develop a “Master List of Energy Conservation Measures Findings”
  • Prioritize and select operational improvements based on payback

Implementation Phase

  • Develop Implementation Plan for Energy Conservation Measures
  • Implement selected operational improvements
  • Verify results
  • Program Results Phase
  • Develop Final Report
  • Compile a Systems Operation and Maintenance Manual
  • Develop Recommissioning Plan
  • Provide training to facilities for operation and maintenance
  • Hold close-out meeting

Why is retro-commissioning important?

For a variety of reasons, buildings experience changes over time that can overload the capacity and performance of the energy using systems, and  prevent optimal performance. Most modern buildings have complex systems that are highly interactive. A small drop in performance of one system will often result in a large effect on building energy efficiency. Retro-commissioning helps to ensure that building equipment and systems are properly controlled and integrated so they perform together effectively, efficiently, and meet the building owner’s current operating requirements and expectations. Studies by utilities and institutions show that most buildings have never gone through any type of commissioning process, and even well-designed and operated buildings experience performance issues  with enough time.

What are the benefits of retro-commissioning?

There are numerous benefits of undertaking retro-commissioning. They include more effective and efficient building operation, energy savings, and improved indoor environmental quality. Everyone benefits from retro-commissioning. For owners, retro-commissioning reduces building operating costs that can lead to an increase in net operating income. Building managers notice fewer occupant complaints and less hassle is required  to manage systems. Building staff has a better understanding of the systems. They receive training and improved documentation. The building occupants are more comfortable which results in higher productivity. Retro-commissioning can also produce significant cost savings in existing buildings. Savings vary depending on the building type, its location, and the scope of the retro-commissioning process. A comprehensive study by Lawrence Berkeley Labs found that the average cost savings provided a commissioning cost payback of 6 months to less than a year.

What is the cost of retro-commissioning?

Today the Total Cost of Retro-commissioning (RCx) -Cost= $0.13 to $0.45/sqft
Average RCx Cost Allocation not including the cost of implementation.

  • - Planning and Investigation 69%
  • - Implementation 27%
  • - Verification, Tracking and Reporting 4%

What is the typical simple payback time =  0.2 to 2.1 years