Title 24: Why Most Projects Fail Acceptance Testing
California’s Title 24 Part 6 has included acceptance testing requirements since the 2005 code cycle [1]. The 2022 code tightened these requirements. The 2025 code, effective January 1, 2026, tightens them again.
If you’re building, renovating, or retrofitting a commercial building in California, acceptance testing is part of getting to certificate of occupancy.
What acceptance testing actually is
It’s a functional verification. Specifically, it confirms the installed controls perform per code and per the documented sequence of operations. Acceptance Test Technicians (ATTs) do the testing [2]. ATTs are certified by an Acceptance Test Technician Certification Provider (ATTCP). There are separate ATT certifications for lighting controls and for mechanical systems.
What gets tested
On the mechanical side: outdoor air ventilation, demand-control ventilation, economizer operation, supply air temperature reset, and demand-responsive controls.
On the lighting side: occupancy sensors, daylight dimming, manual area controls, multi-level controls, and demand-responsive lighting.
Each test has a defined procedure, documented results, and a pass/fail criterion.
Why controls projects actually fail
It’s almost never that the system can’t perform the test. Instead, the failures fall into four categories.
Spec vs. installed mismatch
The sequence of operations as installed doesn’t match the sequence as specified. Somewhere between the design narrative, the submittal, the field programming, and the as-built, things drifted. The ATT runs the test from the spec. The system runs from the field code. They don’t agree.
Sensors are wrong
CO₂ sensors aren’t calibrated. The outdoor-air temperature sensor sits in direct sunlight. Differential pressure sensors are mounted backwards. The control logic is fine. However, the input is lying. See our sensors primer for how to avoid this.
Dampers don’t seal
Economizer dampers bind. Actuators are undersized. The control commands 100% outside air. However, the damper opens 60%. So the test fails not because the controls are wrong but because the mechanical equipment can’t follow.
DCV doesn’t reduce ventilation
The minimum outside air setpoint was set too high “to be conservative.” This defeats the DCV strategy. Code requires a verifiable reduction in outside airflow when occupancy is low.
Three habits that make acceptance testing easy
Spec, submit, program, and as-built the same sequence
This sounds obvious. In practice it requires the controls integrator to read the spec carefully, push back on inconsistencies during submittal review, document any field deviations with engineer approval, and update the as-built when commissioning is complete. Most projects skip steps two and four.
Commission the equipment before commissioning the controls
If the economizer dampers don’t seal, the controls test will fail no matter how good the programming is. So equipment startup, balancing, and mechanical commissioning have to be substantially complete before the ATT shows up. Schedule accordingly.
Pre-test before the official test
The controls integrator and the commissioning agent should walk through the acceptance test procedure together before the ATT arrives. Run every test. Document every result. Fix everything that fails. The official acceptance test should be a verification of work already proven, not a discovery exercise.
How Signet treats the Title 24 metric
First-attempt acceptance test pass-rate is the single metric we treat as the definitive measure of project quality. Every project gets a pre-test. Every deviation gets documented. We track this internally because our clients track it externally — facility teams and engineers remember which integrators caused acceptance-test rework and which ones didn’t. Read more on our Services page.
| Talk to Signet Controls. Planning a BAS install, retrofit, integration, or service contract in California? We work across Los Angeles, Orange County, the Inland Empire, the Central Coast, and Kern County. Reach our team at info@signetcontrols.com or call (877) 874-4638. |
References
[1] NEBB — Everything You Need to Know About California Title 24 — https://www.nebb.org/blog/why-we-all-need-to-pay-attention-to-title-24/
[2] CEC — 2022 Building Energy Efficiency Standards — https://www.energy.ca.gov/sites/default/files/2022-12/CEC-400-2022-010_CMF.pdf
