The Prasino Engineering Guide to Building Commissioning

Introduction

Building commissioning is one of the most valuable investments a building owner can make, yet it remains one of the most misunderstood processes in the construction industry. Many owners first encounter commissioning as a line item on a project budget or a requirement buried in a LEED checklist. This guide is designed to change that.

At Prasino Engineering, commissioning is not a secondary service — it is our core business. With over 45 years of combined experience commissioning mechanical, electrical, life safety, and building envelope systems across higher education, healthcare, mission-critical, K-12, commercial, and transportation facilities, we have developed a deep understanding of what commissioning is, why it matters, and how to do it right.

This guide walks through the entire commissioning process, from the first conversation with an owner through post-occupancy follow-up, and explains the key concepts, standards, and decisions that determine whether a building truly performs as intended.

What Is Building Commissioning?

Building commissioning is a quality assurance process that verifies and documents that building systems are planned, designed, installed, tested, and capable of being operated according to the owner's requirements.

The process typically focuses on systems such as HVAC systems, building automation and controls, electrical systems, lighting controls, domestic hot water systems, renewable energy systems, and life safety systems.

Commissioning ensures these systems operate together as an integrated system rather than simply functioning independently.

Part 1: Why Building Commissioning Is Important

The Core Definition

Building commissioning (Cx) is a quality-focused process for achieving, verifying, and documenting that the performance of facilities, systems, and assemblies meets defined objectives and criteria. The process is led by an independent Commissioning Authority (CxA), who serves as the owner's advocate throughout the project.

The commissioning process is not a final inspection or a punch list. It begins during pre-design, when the owner's goals are first being articulated, and continues through design, construction, acceptance, and the first year of occupancy. Its purpose is to ensure that the building the owner receives is the building the owner asked for.

What Systems Are Commissioned?

A comprehensive commissioning scope typically includes the following systems:

Mechanical Systems

• Air handling units (AHUs), rooftop units (RTUs), and dedicated outdoor air systems (DOAS)

• Variable air volume (VAV) systems and terminal units

• Energy recovery ventilators (ERVs) and heat recovery units

• Variable refrigerant flow (VRF) systems

• Hydronic systems, including chillers, boilers, cooling towers, and pumps

• Building automation systems (BAS) and direct digital controls (DDC)

Electrical Systems

• Emergency and standby power distribution, including generators and automatic transfer switches (ATS)

• Uninterruptible power supply (UPS) systems

• Lighting and lighting control systems, including occupancy sensing, daylighting controls, and demand response

• Critical electrical panels and distribution equipment

Life Safety Systems

• Fire alarm and notification systems

• Smoke control systems

• Integrated life safety system testing, including interlocks with HVAC, elevators, and access control

  
  

Building Envelope

• Air barrier continuity and airtightness

• Thermal performance and thermal bridging

• Moisture control and water management

• Roofing systems, wall assemblies, fenestration, and transitions

  
  

Part 2: The Commissioning Process

Phase 1: Pre-Design

The commissioning process begins before the first drawing is produced. During pre-design, the CxA works with the owner to develop the **Owner's Project Requirements (OPR)** — the foundational document that defines the owner's goals, expectations, and performance criteria for the building.

The OPR addresses questions such as:

• What are the intended uses of the building?

• What are the energy performance targets?

• What are the indoor environmental quality (IEQ) requirements?

• What level of red undancy is required for critical systems?

• What are the expectations for system maintainability and operator training?

  
  

A well-developed OPR is the single most important document in the commissioning process. Every subsequent decision — from design choices to functional performance tests — is evaluated against it.

Phase 2: Design

During the design phase, the CxA conducts formal reviews of the design documents at key milestones, typically at the schematic design (SD), design development (DD), and construction documents (CD) stages. These reviews evaluate whether the design meets the OPR and whether the systems are designed for efficient operation and maintenance.

The CxA also develops the **Commissioning Plan**, which outlines the scope, schedule, and procedures for the commissioning process. The plan is a living document that is updated as the project evolves.

Design-phase commissioning is where the highest-value issues are identified. A conflict between the mechanical and structural drawings, an undersized transfer switch, or a poorly detailed air barrier transition costs far less to correct on paper than in the field.

Phase 3: Construction

During construction, the CxA verifies that the systems are installed correctly and in accordance with the design documents. Key activities during this phase include:

Submittal Review: The CxA reviews equipment submittals to verify that the specified equipment is being provided and that it meets the performance requirements of the OPR.

Site Observations: The CxA conducts regular site visits to observe installation and identify issues early. Observations are documented with photographs and written reports.

Pre-Functional Checklists (PFCs): Before functional testing begins, the CxA develops and administers pre-functional checklists for each piece of equipment. PFCs verify that the equipment is installed correctly, that all connections are made, and that the system is ready for startup and testing.

Phase 4: Acceptance

The acceptance phase is the most intensive period of commissioning activity. It encompasses startup, balancing, and functional performance testing.

Functional Performance Testing (FPT):The CxA develops detailed test procedures for each commissioned system and leads the execution of those tests. Testing verifies that each system operates correctly under all modes of operation, including:

• Normal occupied and unoccupied modes

• Emergency and failure modes

• Seasonal conditions (where applicable)

• Integrated systems testing (e.g., fire alarm activation triggering HVAC shutdown)

All test results are documented in the commissioning report. Issues identified during testing are tracked in the **Issues Log** until they are resolved.

Training: The CxA coordinates and documents the training of facility operations staff. Effective training ensures that the building continues to perform as intended after the commissioning team has left.

Phase 5: Post-Occupancy

The commissioning process does not end at project turnover. A complete commissioning scope includes a post-occupancy review conducted during the first year of building operation. This review typically includes:

• A site visit to observe the building's operation under actual occupancy conditions

• A review of the building automation system trend logs to identify any performance anomalies

• Seasonal testing of systems that could not be fully tested during the acceptance phase (e.g., heating systems tested during summer construction)

• Resolution of any outstanding items from the Issues Log

  
  

At Prasino Engineering, we remain engaged through the warranty period, conducting post-occupancy check-ins to confirm that every issue is resolved and that systems perform as intended long after opening day.

Part 3: Types of Commissioning

New Construction Commissioning (NCx)

New construction commissioning is the application of the commissioning process to a new building project. It is the most comprehensive form of commissioning, encompassing all five phases described above.

Retro-Commissioning (RCx)

Retro-commissioning is the application of the commissioning process to an existing building that was never commissioned or was not commissioned to current standards. RCx is typically performed when a building is experiencing performance problems, when energy costs are higher than expected, or when an owner wants to optimize building performance without undertaking a major renovation.

A retro-commissioning investigation typically begins with a review of utility data, building automation system trend logs, and maintenance records to identify potential issues. Field measurements and testing are then used to verify findings and develop recommendations.

Re-Commissioning (ReCx)

Re-commissioning is the application of the commissioning process to a building that has been commissioned previously. Buildings drift from their original design intent over time due to equipment degradation, control system changes, and evolving occupancy patterns. Re-commissioning restores the building to its original performance baseline.

Building Envelope Commissioning (BECx)

Building envelope commissioning is a specialized form of commissioning focused on the performance of the building enclosure — the walls, roofs, windows, doors, and other assemblies that separate the interior from the exterior environment. Envelope commissioning verifies air barrier continuity, thermal performance, and moisture management.

At Prasino Engineering, our envelope commissioning services include:

• Review of drawings and details for air barrier continuity, thermal bridging, and moisture control

• Field observation of envelope construction, including roofs, walls, openings, transitions, and penetrations

• Documentation of deficiencies and practical recommendations that balance constructability, performance, and cost

  
  

Part 4: Standards and Certifications

ASHRAE Guideline 0 and Standard 202

The primary standards governing the commissioning process are developed by ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers):

• ASHRAE Guideline 0-2019: The Commissioning Process — the foundational document defining the commissioning process for all building systems.

• ASHRAE Standard 202-2018: Commissioning Process for Buildings and Systems — the standard that establishes minimum requirements for the commissioning process.

  
  

LEED Commissioning Requirements

The LEED (Leadership in Energy and Environmental Design) rating system, administered by the U.S. Green Building Council (USGBC), includes commissioning as both a prerequisite and an optional credit:

• Fundamental Commissioning (Prerequisite): Required for all LEED projects. Covers the commissioning of HVAC&R systems, lighting controls, domestic hot water systems, and renewable energy systems.

• Enhanced Commissioning (Credit): An optional credit that extends the commissioning scope to include additional systems, a more rigorous review process, and post-occupancy follow-up.

Prasino Engineering has experience supporting LEED Gold and Silver projects and can provide the commissioning documentation required for LEED certification.

IECC Commissioning Requirements

The International Energy Conservation Code (IECC) requires commissioning for commercial buildings above a certain size threshold. The specific requirements vary by jurisdiction, but generally include commissioning of HVAC systems, lighting controls, and building envelope.

Part 5: Why Choose Prasino Engineering

Independent, Owner-Focused

As a true third-party commissioning firm, Prasino Engineering has no financial interest in the design or construction of the building. Our sole obligation is to the owner, ensuring that the building they receive is the building they asked for.

Licensed Professional Engineers

Every engineer on your project is a licensed Professional Engineer (P.E.). Our team brings deep technical proficiency across mechanical, electrical, and building envelope systems, ensuring that commissioning decisions are informed, accurate, and aligned with industry standards.

Advanced Tools and Technology

We bring our own calibrated diagnostic equipment to every project, including thermal imaging cameras, airflow measurement tools, and building pressure diagnostic equipment. Our proprietary SiteInspector.AI platform enhances the accuracy, consistency, and efficiency of our field documentation and reporting.

Direct Leadership Access

You work directly with the firm's principals from start to finish. No handoffs, no substitutes — just the people whose names are on your proposal, ensuring accountability and consistency throughout the project.