By Lisa Marsh, PE
Building owners sometimes ask, “What is commissioning, and why do I need it?” Sometimes the owner wonders whether they can omit the commissioning process and save the expense. Part of our job as consultants is to educate our customer, the end-user of our design, about the services and products we are providing. So, let’s talk about commissioning. What is it? Why is it needed? And, who benefits from a commissioned building?
What is commissioning?
The simple definition of commissioning is the process of checking each system in the building to make sure everything has been installed as designed and is working as it was envisioned. Although the definition seems simple, the actual process and procedure of commissioning a building can be complex, just like the systems serving the building. The commissioning agent, CxA, is a design professional not associated with the design of the systems. An engineer would not commission their own design, for example. Just as it’s not easy to edit your own writing, it is also not easy to commission your own work or your own design. A fresh set of eyes is always helpful.
Commissioning starts soon after the design of the project, with the CxA making the commissioning plan. For this article, we will discuss only the commissioning of HVAC systems, but many other systems, such as the fire alarm system and lighting design, can also be commissioned.
When commissioning the HVAC system, the CxA develops construction checklists specific to the project and test procedures for the equipment being installed. If the system has hydronic piping, there will be plans to verify the pumps are operating as planned. For the air side and water sides of the design, the CxA verifies that the testing, adjusting and balancing for the systems have been completed. The CxA also looks to see that the contractors completed the startup procedures for the equipment they installed, as well as many other items. Maybe most importantly, commissioning agents have the knowledge and ability to get into the computer programming to analyze whether the HVAC systems have been programmed to operate most efficiently.
Sometimes a building is commissioned after it has been in use for some time, termed retro-commissioning. In buildings we retro-commission, we often uncover system components that were not set up to meet the design intent, underutilizing the sustainable strategies that were provided in construction. The omissions are not due to a lack of care on the part of the mechanical contractor; that person simply may not have the skills, experience or tools to determine that certain components were not set up.
Why does my project need commissioning?
There are several reasons projects need and require commissioning, primarily complexity and building code requirements. HVAC and other building systems are far more complex today than they were several years ago. One example of increased complexity is boiler systems, which require more skills and tools than in the past. Previously, the mechanical contractor could locate the boiler terminal strip and follow the wiring diagram in the installation manual, much like wiring a thermostat to a furnace. The wiring diagram told the contractor to connect the pump to one terminal and the outside air sensor to another terminal, enabling the boiler to run. Following the wiring diagram was a straightforward installation. Today, each boiler has a computer that can be set up in 6 to 8 different configurations. Using a terminal strip is now optional. The changes in HVAC equipment electronic technology has given birth to another subsector of the HVAC industry – controls. The mechanical contractor is often responsible to subcontract the controls work, but may have little time or ability to oversee the work.
Previously, many systems were controlled based only on time of day, whether the building was occupied or unoccupied. We now control outdoor air based on occupancy and CO2 sensors in the space. Previously we would have used pneumatic controls instead of the DDC controls now in use. Because the HVAC systems in our buildings are responsible for about 40% of all energy use, much attention has been given to making them more efficient, so we use less energy and spend less money on energy.
Per the International Energy Conservation code, IECC, building mechanical systems and electrical power and lighting systems require commissioning. There are, of course, exceptions, including the exception for all HVAC systems less than 40 tons of cooling. The construction documents, plans and specifications, must reference the commissioning requirements. The CxA must plan for and provide evidence of the commissioning. The reports required are outlined in IECC, including the preliminary commissioning report, drawings, manuals, system balancing report, final commissioning report, functional testing of the equipment, controls, economizers and other items, is necessary to make sure the systems function as designed and operate as intended. The code requires that the owner receive copies of all commissioning reports.
Who benefits from a commissioned building?
Commissioning is one of the best risk management strategies you can have in construction. The commissioning agent is the owner’s representative, with the knowledge and expertise in construction and facility management to look out for the owner’s best interests. The CxA facilitates a smooth transition from construction to occupancy.
When your building has been commissioned, each system has been reviewed and checked to ensure it is operating as intended. The building owner benefits in lower energy bills and fewer complaint calls, because the building systems are operating properly, inhabitants are comfortable, systems are running when they are supposed to run, and off when they are not needed.
Commissioning is a detailed process to make sure all is as it should be, a process that has grown more arduous as equipment and control systems have increased in complexity over the years. Building codes like LEED and IECC adopted commissioning as a common practice because it is so important to operating a sustainable building. A commissioned property results in lower operating costs, less energy use and fewer problems, something everyone can appreciate.