Back in 2009, a study by Lawrence Berkeley National Laboratory (LBNL) showed that traditional commissioning (Cx) could reduce energy use by 13% in existing buildings and 16% in new construction. Despite the clear benefits, Cx is often slow, manual, and expensive, with median costs of $0.30/sq. ft. for existing buildings and $1.16/sq. ft. for new construction. A big part of this cost comes from wasted site visits, manual issue tracking, and time-consuming Functional Performance Testing (FPT).
That’s where Fault Detection and Diagnostics (FDD) and Automated Commissioning (ACx) come in. These tools cut down on wasted time, streamline testing, and automate data collection, making commissioning faster and more efficient.
What Are FDD and ACx?
FDD (Fault Detection and Diagnostics) continuously analyzes data from the Building Automation System (BAS) to identify faults, inefficiencies, and performance issues. Instead of waiting for occupants to report comfort complaints or discovering problems late in the process, CxA agents can get real-time alerts about failing equipment, faulty sensors, or underperforming systems.
ACx (Automated Commissioning) takes commissioning to the next level by automating system tests and performance verification. Unlike traditional tools, ACx is mobile, meaning CxA agents can deploy it on-site, test hundreds of terminal units in bulk, collect the data, and then take it to the next project. No need for permanent installation—just bring ACx in, run the tests, and move on.
No More Wasted Site Visits: Prefunctional Performance Testing with FDD
A common frustration in commissioning is showing up on-site only to find out that systems aren’t ready. This leads to rescheduling, wasted time, and increased project costs.
With FDD deployed on-site, whether fully or partially as new systems come online, CxA agents can remotely confirm system readiness before heading to the site. This means no more wasted trips and no more scrambling to reschedule work because equipment isn’t installed, programmed, or configured properly.
Goodbye Clipboards: Issue Logs Are Now Automated
Traditional issue logs rely on paper forms, handwritten notes, and manual data entry, which slow down the process and increase the risk of errors. With ACx and FDD, every test and result is automatically recorded. This means no lost paperwork, no deciphering messy notes, and no need to manually enter data after the fact. Instead, Cx teams have real-time visibility into what’s working, what’s not, and what needs to be fixed—without all the extra admin work.
Bulk Testing Instead of Walking the Site: FPT at Scale
Manually testing terminal units is one of the biggest time sinks in commissioning. A typical FPT for VAV boxes, fan coil units, or heat pumps can take 30–60 minutes per unit. Multiply that by hundreds of units in a building, and it’s easy to see why this is such a bottleneck.
With ACx, CxA agents can test hundreds of terminal units at once, instead of walking the site unit by unit. Even better, when ACx and FDD work together, teams don’t just get 100% sampling for the FPT, they can also verify primary equipment performance through terminal unit testing. For example, they can call for 100% airflow on all VAV boxes and instantly check how the AHU responds—something that would take hours with traditional methods.
The Future of Cx: Smarter, Faster, and More Reliable
With FDD and ACx, Cx agents aren’t just solving problems—they’re working smarter. These tools cut down wasted time, automate repetitive tasks, and provide real-time insights that make commissioning faster, more efficient, and more data-driven. As the industry shifts toward smarter buildings, mobile ACx solutions and advanced FDD will be the new standard for commissioning teams looking to maximize efficiency and minimize headaches.