Commissioning is a process where qualified professionals verify that the performance of building systems matches the specifications in the approved construction documents. In the case of New York City, commissioning requirements are established in the NYC Energy Conservation Code, Section C408. The 2014 edition of the code made commissioning mandatory for the following installations:
Although commissioning was already detailed in the ASHRAE 90.1 Energy Standard for Buildings, there was no legislation making it mandatory in New York City. However, this changed with the 2014 NYC Energy Conservation Code, as part of the city’s effort to meet its emissions reduction target - 80% by 2050. This article will provide an overview of the mechanical commissioning requirements and procedures in New York City.
It is important to note that mechanical commissioning is not mandatory for buildings with heating and cooling systems below a specified capacity. Buildings that meet the two following conditions are exempt from the commissioning requirements in the NYC Energy Conservation Code:
- The total cooling capacity installed is below 480,000 BTU/hour (140.7 kW)
- The combined space and water heating capacity is below 600,000 BTU/hour (175.8 kW)
When counting the total heating or cooling capacity, both renewable and nonrenewable technologies count. If mechanical commissioning is required, keep in mind that the process involves not only heating and cooling equipment, but also associated systems like air handlers, economizers and controls.
Starting Point: The Commissioning Plan
Before starting the commissioning process, an approved agency must develop a commissioning plan for the project, and the following information must be included:
- Description of activities during each phase of commissioning, and the required staff.
- A list of equipment, appliances and systems to be tested. The list must include their operating sequences, a description of the planned tests, as well as any prerequisites and documentation to be used in the process.
- Functions to be tested: Calibration, economizer controls and other similar functions.
- Conditions required for each test, including season of the year and outdoor air conditions.
- Measurable performance criteria.
Adjusting & Balancing
The Energy Conservation Code requires that all HVAC systems in New York City buildings be balanced as specified in the ASHRAE 111 Standard (Practices for Measurement, Testing, Adjusting & Balancing of Building HVAC and Refrigeration Systems). The procedure includes all air ducts and hydronic piping systems.
- Discharge dampers are not allowed on fans with motors larger than 10 hp. This applies for both constant-volume and variable-volume systems.
- The priority when balancing air systems is to minimize throttling losses, and then fans above 1 hp must use speed adjustment to meet the design airflow.
- Air balancing is not required for fans with motors rated at 1 hp or less.
The NYC Energy Conservation Code also provides basic guidelines for adjusting and balancing hydronic systems:
- Individual heating and cooling coils must be equipped with a flow measurement and balancing system.
- Like with air systems, the priority when balancing hydronic systems is to minimize throttling losses, and then trim pump impellers or control their speed to meet the design waterflow.
- Hydronic systems must be equipped with a system capable of measuring the pressure difference across pumps.
- Exceptions: Flow measurement and balancing are not necessary for pumps with a motor rated at 5 hp or less, or where the horsepower increase due to throttling is 5% or less.
Functional Performance Testing
Mechanical performance testing is split into three main areas in the NYC Energy Conservation Code: equipment, controls and economizers.
The installation, operation and maintenance serviceability of mechanical equipment is assessed according to the approved construction documents; and the testing procedure is carried out for full-load, part-load and emergency conditions. Unitary or packaged HVAC systems that don’t require economizers and are listed in section C403 only require full-load and part-load testing.
All controls used in HVAC and service water heating systems are tested to ensure their calibration meets the specifications in the approved construction documents. The testing procedure must be documented, and it includes sequences of operation.
All economizers must be tested to verify operation according to manufacturer specifications.
Preliminary Commissioning Report
Commissioning tests and procedures are documented in preliminary commissioning report, which is certified by an approved commissioning agency and presented to the building owner. The report must clearly identify any deficiencies that have not been corrected at the time of its completion, as well as any tests postponed due to specific weather requirements
Final inspection and approval of the project cannot proceed until the Preliminary Commissioning Report has been delivered to the building owner. The NYC Dew York Cityepartment of Buildings can request a copy of the report if considered necessary.
Documentation Requirements After Project Approval
The following documents must be delivered to the building owner within 90 days after receiving the certificate of occupancy or letter of completion:
- Drawings detailing the location and performance of each piece of equipment.
- Operation and Maintenance Manuals according to Article C408.2.5.2 of the Energy Conservation Code.
- A System Balancing Report describing the activities carried out during the adjusting and balancing phase of the commissioning process.
Final Commissioning Report
As implied by its name, this report details all test procedures and results of the commissioning process, including those carried out after legal occupancy of the building. The final report must include the corrective measures used or proposed for any deficiencies that had not been addressed when the preliminary report was delivered.
The time limit for delivering the final commissioning report varies depending on building characteristics:
- 18 months after the Certificate of Occupancy is emitted, for buildings with an area below 500,000 gross square feet. and all R-2 occupancies regardless of area.
- 30 months after the Certificate of Occupancy is emitted if the building has an area of at least 500,000 gross square feet (excluding R-2 occupancies).
Although mechanical commissioning may seem like an extra burden for projects in New York City, it actually provides many benefits. First of all, project owners can rest assured that building systems offer the performance they paid for. In addition, long-term ownership costs are lower, since commissioning reduces energy and maintenance expenses. In the case of HVAC installations, commissioning also helps improve indoor air quality, which is beneficial for occupant health.
Working with qualified professionals is the best way to ensure that your project meets the commissioning requirements in the NYC Energy Conservation Code, as well as any other applicable codes and standards.
Editors Note: This post was originally published in June 2017 and has been revamped and updated for accuracy and comprehensiveness.