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Performance issues in buildings often creep in slowly. HVAC systems drift out of sync with occupancy patterns. Sensors get out of calibration. Lighting schedules stay static while usage evolves. Nothing is outright broken, but the system as a whole no longer works as efficiently as it could.

This kind of slow, silent drift is common, especially in buildings that weren’t designed with modern efficiency standards in mind. For facility managers under pressure to control costs, reduce carbon emissions, and improve occupant comfort without major capital investment, it presents a frustrating dilemma. Retro-commissioning (RCx) offers a solution.

What is retro-commissioning—and why does it matter?

Retro-commissioning (RCx) is the process of evaluating and optimizing the performance of existing building systems, especially HVAC, lighting, and controls, to bring them back in sync with how the building is used. Think of it as a tune-up for your facility: no major capital investment required, just better energy efficiency.

The impact can be significant. According to the Lawrence Berkeley National Laboratory study:

• Energy savings average of 15% in existing commercial buildings
• Median payback of just 1.1 years
• Average cost is around $0.30 per square foot

Beyond the energy savings, RCx often improves ventilation, thermal comfort, and indoor air quality contributing to occupant wellness and satisfaction in a measurable way.

These numbers align with what Salas O’Brien teams see in the field, but many clients have exceeded them, achieving deeper savings and broader operational gains by targeting the right issues at the right time.

It’s not broken—but it’s not working either: five clear signals

One of the challenges with retro-commissioning is that the need for it isn’t always obvious. A building can appear to be running smoothly—systems are on, spaces are occupied, no alarms are going off—but still be far from optimized. Over time, small inefficiencies layer on top of each other, quietly increasing costs and reducing performance.

How do you know when it’s time to take a closer look? Here are five signs that your building may benefit from retro-commissioning:

1.    Occupant complaints are increasing.

If you’re hearing more about temperature swings, drafty zones, inconsistent lighting, or general discomfort, it’s usually not a one-off issue. It’s a signal that something systemic is off. RCx helps uncover and address the root causes behind recurring complaints.

2.    Energy bills are going up without a clear explanation.

It’s easy to attribute rising costs to utility rate changes, but often the bigger culprit is rising consumption. Out-of-sync controls, misconfigured schedules, and equipment running longer than necessary can all drive up usage without anyone noticing until the bills arrive.

3.    A drop in productivity or satisfaction.

Comfort, indoor air quality and even minor maintenance issues can have a quiet but compounding effect on staff or occupant productivity. When people are uncomfortable or distracted, performance suffers and absenteeism can increase too. RCx supports healthier, more consistent environments that help people stay focused and engaged.

4.    Work orders are piling up.

An uptick in reactive maintenance requests can be a red flag that systems are drifting out of alignment. Retro-commissioning brings those patterns into focus, helping reduce the volume of day-to-day firefighting and giving your team room to be more strategic.

5.    Systems are working—but not working together.

When HVAC, lighting, and controls were installed at different times and tweaked over the years without a holistic strategy,  systems can begin to operate at cross-purposes. For example, heating and cooling might run simultaneously in different zones, or ventilation rates might not respond to real-time occupancy. RCx reveals these hidden mismatches and helps systems work with each other, not against.

These signals often show up gradually, which is exactly why they’re easy to overlook. But taken together, they point to a building that may not be broken but isn’t operating as efficiently or reliably as it could. RCx offers a low-risk, high-return way to reset performance.

What RCx finds more often than you’d think

Most buildings have at least a few things quietly working against them. Issues that don’t trigger alarms but add up to higher costs and lower comfort. In retro-commissioning projects, certain patterns come up again and again.

One of the most common issues is out-of-calibration sensors and controls. These often lead to improper heating and cooling setpoints that drift far from what’s needed. That can translate into rooms that are too hot or too cold, inconsistent airflow, and occupant complaints that seem tough to pin down.

Another frequent issue is inefficient scheduling. Equipment runs long hours, sometimes 24/7, regardless of whether the building is fully occupied. This is especially common in institutional and campus settings, where usage patterns can shift frequently. Without a scheduling strategy that reflects real-time needs, systems waste energy just keeping empty spaces comfortable.

And then there’s simultaneous heating and cooling, a classic sign of poor coordination between systems. It’s a hidden energy waster, and surprisingly common in large buildings with layered HVAC strategies.

RCx brings these inefficiencies to the surface and offers a path to correct them, usually without needing to replace a single piece of equipment.

How RCx is different from an energy audit

Energy audits and RCx often get grouped together, but they serve different purposes. Audits tend to focus on capital improvements: upgrading lighting, replacing boilers, or investing in long-term energy strategies. RCx, on the other hand, is all about optimizing what’s already in place.

Where audits identify what to replace, RCx asks: Are the systems we have working the way they should? It’s focused on operations, controls, and sequencing, things that often slip over time and quietly drive up costs. Most of the fixes are low cost, fast payback, and immediately actionable.

The two approaches can absolutely complement each other, but RCx is often the more strategic first move. The optimization that RCx provides is usually a lower cost than capital improvements with less “red tape” to execute.

Where retro-commissioning breaks down: the follow-through gap

Retro-commissioning is one of the smartest investments a facility can make, but like any process, its value depends on follow-through.

One of the built-in challenges is that the full scope of required fixes isn’t clear at the outset. The investigation and testing phases reveal where systems are underperforming, but until that’s complete, it’s difficult to pin down the total cost of implementation. That uncertainty can complicate budgeting and delay internal approvals.

And here’s the real “gotcha”: sometimes, facilities go through the entire RCx process—paying for the study and receiving the recommendations—but never implement the fixes. When that happens, the building stays in status quo mode, and the potential savings are left on paper.

How Salas O’Brien can help

Salas O’Brien can help by tailoring an RCx project to the unique needs of the building. The Pareto Principle often applies with 20% of the systems causing 80% of the problems. A shotgun approach is expensive. Salas O’Brien can align to what matters to a specific building or portfolio of buildings.

We approach retro-commissioning with both technical depth and a strong understanding of how buildings actually operate day to day. We bring experience across a wide range of facility types including laboratories, healthcare environments, higher education campuses, multi-family housing, and complex industrial and manufacturing settings.

Most importantly, we tailor every RCx project to your goals, your budget, and your building’s real-world behavior.

From discovery through implementation, we’re here to help you get the full value from your systems without overextending your team or resources.

Reach out to one of our contributors below to talk about your project.

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