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The Gremlins of an Occupied-Building BAS Cutover: What Altura and McCarthy Learned Across Two Healthcare Projects
Altura (MSI) and McCarthy (controls contractor) collaborated on a project to upgrade outdated building automation systems in occupied medical office buildings. The work was scheduled for the graveyard shift to avoid a shutdown, and the mandate from the owner's rep was that the "medical staff should never know anyone had been in the building."
Existing buildings hide their problems, and these two buildings had been Frankensteined together over decades, with mixed controls vintages. A BAS upgrade means touching nearly everything, and once you touch it, you own it. At NexusCon 2025, Altura and McCarthy shared the most important lessons they gained from this project.
The most expensive lesson was the change-of-value settings for trending. The team ran COV on every data point in the buildings, and although the controller vendor's BACnet documentation listed COV support, it did not hold up at that scale. Controllers stopped updating, and it took months to isolate the cause amid finger-pointing between the front end and the field. The fix required new firmware to roughly 800 to 900 controllers across both buildings that allowed the controllers to handle the COV communication requirements. The takeaway for any integrator: don't always trust a controller's capabilities based on it's spec sheet.
Altura shared two additional hindsight lessons.
First, connecting analytics before the cutover rather than after would have given the team a performance baseline to compare against when behavior drifted.
Second, good operator engagement at one building compared to little engagement at the second building showed a start difference. The building whose operators stayed involved handed over the historical knowledge that as-builts never capture, down to which VAVs were served by which air handlers, which made the nightly cutovers smoother and surfaced savings later, like shutting down an air handler that served a single zone.
Upgrading a live healthcare building means inheriting decades of hidden conditions - one of the most difficult controls jobs a service provider can be involved in. Success, as Altura and McCarthy showed us, relies on relentless preparation and communication.
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Altura (MSI) and McCarthy (controls contractor) collaborated on a project to upgrade outdated building automation systems in occupied medical office buildings. The work was scheduled for the graveyard shift to avoid a shutdown, and the mandate from the owner's rep was that the "medical staff should never know anyone had been in the building."
Existing buildings hide their problems, and these two buildings had been Frankensteined together over decades, with mixed controls vintages. A BAS upgrade means touching nearly everything, and once you touch it, you own it. At NexusCon 2025, Altura and McCarthy shared the most important lessons they gained from this project.
The most expensive lesson was the change-of-value settings for trending. The team ran COV on every data point in the buildings, and although the controller vendor's BACnet documentation listed COV support, it did not hold up at that scale. Controllers stopped updating, and it took months to isolate the cause amid finger-pointing between the front end and the field. The fix required new firmware to roughly 800 to 900 controllers across both buildings that allowed the controllers to handle the COV communication requirements. The takeaway for any integrator: don't always trust a controller's capabilities based on it's spec sheet.
Altura shared two additional hindsight lessons.
First, connecting analytics before the cutover rather than after would have given the team a performance baseline to compare against when behavior drifted.
Second, good operator engagement at one building compared to little engagement at the second building showed a start difference. The building whose operators stayed involved handed over the historical knowledge that as-builts never capture, down to which VAVs were served by which air handlers, which made the nightly cutovers smoother and surfaced savings later, like shutting down an air handler that served a single zone.
Upgrading a live healthcare building means inheriting decades of hidden conditions - one of the most difficult controls jobs a service provider can be involved in. Success, as Altura and McCarthy showed us, relies on relentless preparation and communication.
Register for the next Nexus Labs event.
Sign up for the newsletter to get 5 stories like this per week:
This is a great piece!
I agree.