The Value of Functional Testing and Commissioning: Beyond Compliance

As the construction and energy efficiency industries evolve, so do the standards that govern them. The 2025 Michigan Energy Code introduced new requirements for functional testing and commissioning in commercial buildings, further enforcing mandatory commissioning for projects impacting over 10,000 square feet and providing much-needed clarity on what the process entails. While some may view these changes as just another regulatory hurdle, functional testing and commissioning are far more than compliance checkboxes—they are critical tools for ensuring that buildings perform as intended, deliver energy savings, and provide lasting value to owners and occupants.

Codes and Standards: The 2025 Michigan Energy Code

The new Michigan Energy Code, enforced starting April 23, 2025, mandates functional performance testing and commissioning for commercial buildings and projects of certain sizes. The code references ASHRAE Standard 90.1–2019 and the 2021 IECC, both of which require verification or functional performance testing of building systems, controls, and building envelopes. Importantly, the code stipulates that testing cannot be performed by individuals involved in the design or installation of systems and assemblies—to avoid conflicts of interest and ensure unbiased validation. Instead, this can be a qualified employee or an independent third party. 

Functional performance testing is required for any new construction, addition, or major alteration. The scope of testing depends on the systems affected by the project. For example, if only mechanical systems are changed, only those systems require testing. The results, certified completion, and plans for deferred testing must be documented and provided to the owner.

What is Functional Testing and Commissioning?

Functional testing, sometimes referred to as functional performance testing (FPT), is a systematic process that evaluates and documents whether building systems and equipment operate according to manufacturer specifications, design intent, and owner’s project requirements. According to ASHRAE Standard 202–2018, functional testing involves the evaluation and documentation of equipment and assemblies, their delivery and condition, installation, and proper function. The International Energy Conservation Code (IECC 2021) further defines it as the demonstration and documentation of the installation and operation of components, systems, and their interfacing relationships in accordance with approved plans and specifications.

Commissioning, as described by the Building Commissioning Association (BCxA), is a quality-focused process for enhancing project delivery by achieving, validating, and documenting the performance of facility elements to meet the owner’s objectives. It accompanies a project from start to finish. This includes both verification of correct installation and functional performance testing of installed systems—ensuring, for example, that variable speed systems actually vary their speed as designed, and that the design is what the owner required. 

By definition, all commissioning will include functional testing, but functional testing can be conducted outside of a commissioning process. This makes functional testing a valuable and flexible engineering tool.

The Goals of Functional Testing

Functional testing is not just about ticking boxes, as it serves to achieve several crucial goals:

Pinpoint Chronic Issues: Chronic problems can impact occupant comfort, energy usage, system efficiency, and maintenance downtime. Functional testing helps identify these issues early, preventing costly fixes and operational headaches down the line.

Verify Proper Installation and Operation: By referencing design contract documents, manufacturer specifications, and owner’s requirements, functional testing ensures that systems are installed and operating as intended.

Isolate System Operations: Testing can be component-specific (e.g., confirming damper operation), system-specific (e.g., heating system performance), or inter-system (e.g., interactions between mechanical cooling and free cooling systems). It can also be a combination of the three, depending on the scope of the project and systems impacted.

Establish and Document Baseline Operation: Functional tests provide benchmarks for future operational situations, helping owners and operators compare performance over time and identify deviations.

Improve System Maintenance and Operation Procedures: Written, repeatable testing processes give building operators additional guidelines needed to keep systems running optimally.

The Benefits of Functional Testing and Commissioning

The benefits extend well beyond code compliance:

Establishes an Operational Baseline: Thorough documentation creates a roadmap for future troubleshooting and benchmarking. When issues arise, operators can reference how systems functioned at the time of commissioning and testing.

Flexible Scope: Commissioning and functional testing can be tailored to the needs of new construction or existing buildings and can focus on individual systems or integrated operations. Not all projects look the same, and the verification scope should reflect that.

Objective Results: The pass/fail outcomes of functional testing remove subjectivity and finger-pointing, providing clear answers about system functionality.

Supports Owner’s Project Requirements: Both processes are closely aligned with the owner’s goals, whether those are energy efficiency, occupant comfort, or specific areas of concern.

Facilitates Benchmarking: As cities like Detroit require benchmarking, functional testing and commissioning provide much of the necessary data – integrating compliance with operational excellence.

Real World Examples: Issues Identified and Fixed

Some of the real-world examples that we have encountered during our work, outlined below, further underscore the value of functional testing and commissioning:

New Construction

VAV Box Dampers Over-Rotate: In one project, dampers were unable to close properly, leading to inaccurate airflow during auto-recalibration. The commissioning process helped identify the issue before it impacted occupant comfort and energy usage.

Installation and Wiring Issues: An AHU supply fan would not turn off when commanded to do so. During functional testing of the controls, it was found that the wiring was installed incorrectly. This identification prevented excess equipment run time and energy usage.

System Integration Challenges: Occupancy sensors and auto receptacles were not working due to setup and testing difficulties. Functional testing eliminated finger-pointing and united the team to resolve the issues.

AHU Outside Air Dampers: AHU outside air intake was found to be at 100% continuously due to incorrect installation. Since the damper was not responding to controls, it would be very difficult for operators to catch without in-depth trend analysis. Functional testing of the dampers identified the issue, preventing increased energy usage and maintenance.

Existing Buildings

Hot Water Issues: A lack of hot water in bathrooms was traced not to the heater itself, but to the control, avoiding unnecessary equipment replacement.

Cooling Problems: Inadequate cooling in a ballroom since installation was resolved by functional testing. This prevented the purchase and installation of an additional rooftop unit, saving the customer time, energy, and money.

Thermostat Mapping Errors: A thermostat mapped incorrectly to a closet instead of the intended space was identified, and through systematic functional testing. Long-standing space temperature issues were resolved by simply moving a thermostat.

Forgotten Operator Overrides: Building schedule overrides buried in system programming prevented equipment from turning off during unoccupied hours. This can be a common occurrence in facilities with lots of non-routine events that require schedule adjustments. Functional testing of the equipment controls provided efficient troubleshooting to identify this issue and provided an opportunity for operator training.

These real-world examples demonstrate a variety of ways that even brand-new systems can have flaws, and that functional testing is essential for uncovering and resolving issues that might otherwise go unnoticed.

Functional testing and commissioning are not just new requirements under the 2025 Michigan Energy Code—they are indispensable practices for ensuring that buildings deliver on their promises of energy efficiency, occupant comfort, and operational reliability. By systematically verifying and documenting system performance, these processes close the gap between design intent and real-world operation, providing owners with the assurance that their investments will perform as expected.

To learn more about how Energy Sciences can help you with functional testing and commissioning, visit https://energysciencesllc.com/solutions/.