Ongoing and monitoring-based commissioning

Commissioning and retro-commissioning bring a building's systems to a well-tuned state. Then time takes over. Sensors drift, actuators fail, schedules get extended, overrides are left in place and new tenants change how spaces are used. Without continuing attention, performance gradually slides back toward where it started.

Ongoing commissioning (OCx) and monitoring-based commissioning (MBCx) are approaches for preventing that decline. Instead of treating commissioning as a project with an end date, they make it a continuous part of operations, using the data the building already produces to catch problems early.

Definitions

The terms are used loosely in the industry, but a practical distinction is:

• Ongoing commissioning is a continuing process of verifying and optimizing building performance through periodic reviews, testing and corrective action. It can be done with relatively simple tools such as scheduled trend reviews and recurring functional checks.
• Monitoring-based commissioning is a form of ongoing commissioning that relies on permanent monitoring: energy meters, BAS trend data and analytics software, often including automated fault detection and diagnostics (FDD). The emphasis is on continuous data analysis rather than periodic site visits.

Both share the same goal: detect when performance deviates from intent and fix it quickly. ASHRAE Guideline 0.2, covering commissioning of existing systems, and the commissioning process described in ASHRAE Standard 202 both recognize this continuing phase.

Building blocks of an MBCx program

Metering

Whole-building electricity and gas meters provide the top-level view, ideally at 15 minute or hourly intervals. Submetering of major end uses, such as chillers, boilers, air handlers, lighting and plug loads, makes it much easier to locate problems. Thermal energy meters on heating and chilled water loops are valuable in larger buildings and in those connected to district energy.

BAS trend data

Trends of temperatures, setpoints, valve and damper positions, fan and pump speeds and equipment status form the core dataset. See trend logging and using BAS data for which points to collect and at what intervals.

Analytics and FDD

Software platforms analyse the data, apply fault detection rules, estimate the cost of faults and present results in dashboards and reports. Fault detection and diagnostics explains how these tools work and how to choose one.

Energy baseline

A weather-normalized energy baseline, built from historical utility data using regression against heating and cooling degree days, allows actual consumption to be compared with expected consumption. A sustained deviation indicates a problem even before its cause is known. The same techniques underpin measurement and verification of energy savings.

People and process

Data on its own fixes nothing. A successful program defines who reviews the results, how often, how issues are assigned and how resolution is confirmed.

A typical program cycle

1. Monitor continuously. Data is collected and analysed automatically, with faults and energy deviations flagged.
2. Review regularly. A commissioning provider or in-house analyst reviews findings, often weekly or monthly, and filters out false positives.
3. Prioritize. Issues are ranked by energy cost, comfort impact, equipment risk and ease of correction.
4. Assign and correct. Issues are entered into the maintenance work order system and assigned to operations staff or contractors.
5. Verify. Data confirms that corrections worked and stayed in place.
6. Report. Periodic reports track faults found and fixed, energy performance against baseline and outstanding items.
7. Improve. Rules, thresholds and baselines are refined, and recurring issues are escalated for deeper investigation or capital planning.

What ongoing commissioning catches

Ongoing commissioning in new buildings

On new construction, MBCx can begin at occupancy and continue through the warranty period. It helps verify seasonal performance, identify issues while contractors are still obligated to correct them and give operators a strong start. The LEED v4 and v4.1 enhanced commissioning credit includes a monitoring-based commissioning option, which requires a plan for ongoing monitoring of energy and water performance after occupancy. See commissioning for LEED and green building programs.

Getting started in an existing building

For most existing buildings, the most effective path is:

1. Complete a retro-commissioning project to fix the backlog of existing problems.
2. Confirm that metering and BAS trending cover the key systems, and fill critical gaps.
3. Establish an energy baseline after retro-commissioning measures are complete.
4. Select an analytics approach that fits the building and staff capacity, from a structured monthly trend review to a full FDD platform.
5. Define the review cycle, responsibilities and reporting.

Small buildings with limited BAS capability can still benefit from a simplified program: monthly utility tracking, quarterly schedule and override reviews, and an annual check of key sequences.

Challenges

• Data quality. Gaps, mislabelled points and inaccurate sensors undermine analysis. Invest in fixing these early.
• Alert fatigue. Too many low-value notifications cause people to stop looking. Prioritize ruthlessly.
• Staff capacity. Operations teams are often stretched. A program must fit their workload or include external support.
• Network security. Sending BAS data to cloud platforms requires a secure architecture agreed with IT.

Frequently asked questions

Is MBCx only for large buildings?

It is most common in large and complex buildings, where the savings justify the platform cost. Smaller buildings can use simpler, periodic ongoing commissioning methods with good results.

How is ongoing commissioning different from preventive maintenance?

Preventive maintenance keeps equipment in good mechanical condition. Ongoing commissioning makes sure systems are operating correctly and efficiently as a whole. The two complement each other.

Key takeaways

• Building performance drifts after commissioning unless someone keeps watching.
• Ongoing commissioning uses periodic reviews; MBCx adds permanent metering, trend data and analytics.
• A weather-normalized energy baseline reveals problems before their cause is known.
• Success depends on clear responsibilities, prioritization and verification of fixes, not just software.
• Starting with retro-commissioning, then moving to continuous monitoring, protects the savings. Our retro-commissioning work can include setting up this transition.