Retro-Commissioning: Reoptimizing building systems for energy efficiency

Buildings are complex machines. When they’re shiny and new and everything is running great, facility managers feel like the kings or queens of the world. But it doesn’t take long for that lustre to wear off. What comes then?

As buildings get older things to start falling out of spec. A damper is stuck open. An engineer overrode a setpoint and didn’t tell anyone. An occupant props a window open. A BAS module crashes and doesn’t reset. And these are just the tips of the iceberg. As Facilitiesnet expert, Greg Zimmerman explains: buildings are complex machines and lots can go wrong.

The retro-commissioning process

This is why it’s crucial to periodically review a building’s energy-using systems. First, to ensure, they’re running as intended, then to check if they’re optimized for maximum energy efficiency and occupant comfort. Retro-commissioning is the process of reoptimizing building systems for energy efficiency. It’s a low-cost strategy with a strong payback story.

The Environmental Protection Agency reports retro-commissioning can save up to 15 % on energy and with a payback of less than a year – the article states. Zimmerman mentions the example of the Capitol campus in Washington, D.C., with a stated goal of reducing energy use by 50 % by 2025. The ongoing project saved conservatively between 5 and 10 % in real-world energy use with a recent retro-commissioning.

Here is how to start

To start a retro-commissioning project in your building, the first step is to identify the major energy-using equipment. It’s often helpful to bring on board a commissioning expert to ensure the most savings.

EPA recently published a report highlighting the major drivers of high energy performance and it shouldn’t be a surprise that the majority of the impact is driven by operations and maintenance (69 %). Building teams must better understand what, where, and how to make their buildings perform better if they have any realistic opportunity to achieve their specific carbon, energy, water, waste/recycling reduction goals, or even carbon neutrality. If building energy performance is really 69 % driven by O&M procedures, it makes the most sense to examine specifically which systems are consuming the most, when they are operating, and why. Retro-commissioning is a great first step in how teams can go about correcting the most basic of O&M concerns – says Rock Ridolfi, director of project operations for consulting firm Rivion.

Why is monitor-based commissioning an important part of an energy-saving strategy?

The main goal for monitor-based commissioning (MBCx) is simply creating a formal action plan to maintain better oversight and performance tracking on a more frequent basis. Implementing MBCx plan enables teams to react faster to variations in building performance. When teams can react faster or allow a software to identify anomalies, they may enact solutions which may reduce or eliminate consumption outside of standard usage patterns. Ridofil suggests developing monitoring-based procedures and identifying points to be measured and evaluated to assess the performance of energy- and water-consuming systems. Include the procedures and measurement points in the commissioning plan.

Address the following:

  • Roles and responsibilities;
  • Measurement requirements (meters, points, metering systems, data access);
  • The points to be tracked, with frequency and duration for trend monitoring;
  • The limits of acceptable values for tracked points and metered values (where appropriate, predictive algorithms may be used to compare ideal values with actual values);
  • The elements used to evaluate performance, including conflict between systems, out-of-sequence operation of systems components, and energy and water usage profiles;
  • An action plan for identifying and correcting operational errors and deficiencies;
  • Training to prevent errors;
  • Planning for repairs needed to maintain performance; and
  • The frequency of analyses in the first year of occupancy (at least quarterly).

Building technology enhanced the capabilities of FMs

Many systems can connect to smartphones. This keeps facility managers fully engaged with their building without the need for being onsite 24/7. This further amplifies the benefits of a MBCx system. Nearly 50 % of commercial office buildings are still limited to monthly or quarterly utility data for energy and water. They significantly delayed in responses to unknown building operations, which may not be fully highlighted through a legacy BAS with no IoT-connected devices.


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