Michael P. Della Barba, CBCP, Environmental Health & Engineering, Inc.
John F. McCarthy, Sc.D., C.I.H, Environmental Health & Engineering, Inc.
Building commissioning is a detailed process of review, verification and documentation to ensure that all building systems and components are designed, installed and performing optimally and according to the owner’s project requirements. System performance directly impacts occupant comfort, maintenance frequency, equipment life and energy usage. In new construction, building commissioning is most effective when initiated during the design phase to achieve the maximum benefit. A major benefit obtained in the design review is that the Commissioning Agent (CA) can compare the design assumptions being employed with the owner’s intent and/or best practices for similar building programs, and promote discussion to reconcile any differences early in the process.
Every building undergoes changes. Spaces are repurposed, interior structures are modified, and people are moved around. These changes can negatively impact building performance, resulting in higher energy and maintenance costs and decreased equipment life.
‘Recommissioning’ and ‘retrocommissioning’ are often used interchangeably for existing buildings. Generally recommissioning infers reevaluating performance parameters recorded during a previous commissioning effort, while retrocommissioning applies to evaluating performance of building systems that were not previously commissioned. Every building undergoes changes over time. Spaces are repurposed, interior structures are modified, and people and departments are moved around. These changes can negatively impact building performance, resulting in higher energy and maintenance costs and decreased equipment life. Recommissioning provides a complete, up-to-date picture of your facility’s true performance, potentially uncovering costly hidden issues.
The commissioning process identifies deviations or deficiencies between actual construction, and the project design portrayed by the project drawings and specifications (contract documents). These deviations are documented in the Commissioning Action List (CAL).
Commissioning (Cx) applies a process of review, verification, and documentation so that the final product, the building required to meet the needs of its occupants, conforms to the project design requirements in every way. It should be understood that the final product is developed and constructed in layers over time in an often uncontrolled or discontinuous environment.1 Commissioning can be the link between the different phases of the project to ensure the buildings’ effectiveness is not compromised during value engineering review or program modifications. Commissioning is most effective when applied to all construction phases or layers with an inchstone mentality. This ensures that by the time of system acceptance, individual components have been debugged and that system testing is being performed on a system of properly functioning parts.
A 2016 review of 9 completed projects inclusive of high-rise residential, office, educational, laboratory and healthcare space, and ranging in size from 150,000 to 530,000 square feet revealed the following results:
|Average number of CAL issues||740|
|Average number of CAL issues open at final Cx report||40|
|Average number ofcritical issues found||50|
|Average number of critical issues open at final Cx report||1|
CAL – Commissioning Action List | Cx – Commissioning
An average of 740 issues identified on large projects represents the product of a quality assurance function (commissioning). The question becomes: what is the impact if these issues were not identified? At the very least, the value of the purchased product is diminished. At the most extreme the effective functioning of the building may be compromised and manifest itself in conditions that compromise either health, comfort or safety of occupants or in the intended ability to support the basic functions the building was designed for.
The average number of open (unresolved) issues at occupancy recognizes that the client has taken ownership (basis of construction contract) with 40 items outstanding. At this point, the impact of open items gets transferred to the owner in terms of maintenance, energy use and occupant production. The issues may still be correctible by the construction team, but the owner is now experiencing the impact of a non-conforming item.
The 2016 review noted that an average of 50 items were defined as critical or issues that have a major impact on system performance. The majority of these items are identified during system performance testing. In the absence of commissioning these critical issues are identified by the owner sometime after occupancy and usually with major consequences.
Flawed components identified in the CAL that are not critical may not necessarily prevent equipment and systems from operating, nor necessarily prevent occupancy. They may, however, eat away at the value of the final product originally expected or cause unexpected capital and operating and maintenance expenditures in the future. What is the penalty for missing insulation or piping unions, duct or building envelope leakage, unlabeled piping or electrical panels, defective or faulty control sensors, controls programming errors, mis-sized condensate traps, and under-ventilated confined spaces – and the list goes on? The answer can come from most any building facilities or operations and maintenance department and will include adversely impacting occupant comfort, increased energy usage, premature equipment replacement, increased maintenance time and expense, and more.
As described in the 2007 article “Elements That Contribute to a Healthy Building Design”2 , key elements are:
All of these design elements are really dynamic systems that consist of multiple components and by necessity must respond to environmental conditions that can vary by time of day and season or specific building activities.
By definition, commissioning is a process that helps ensure that the building design is realized (i.e., purchased and constructed per design). Even the best designs will be negatively impacted by construction shortfalls that result in unintended consequences and sub-par performance, if they are not identified and corrected in a timely manner. The timing of the commissioning process can also have a significant impact. Performance issues identified during the design phase or early construction can be corrected with little or no impact on construction cost or schedule. Issues identified later in construction impact cost and schedule and may impact design performance if identified too late to effectively rectify.
In Building Ecology: An Architect’s Perspective on Healthy Buildings3 Hal Levin wrote: “A healthy building is one that adversely affects neither the health of its occupants nor the larger environment. Indoor air quality (IAQ) concerns are among many indoor environmental issues that must be addressed to avoid impacts on occupants’ health and well-being”. In regard to designing healthy buildings he states, “Designers only control the intended construction; builders, users, managers and others determine many building factors that determine indoor air quality”. Levin continues, “the indoor air factors under the control of the designers are the materials and systems, the ventilation, the environmental control scheme, the layout, etc. All of these significantly affect indoor air quality and other environmental factors. However, any dysfunction in the indoor environment potentially affects occupant health and well-being. When buildings fail to do what they are intended to do, indoor environmental pollution in the form of indoor air pollution, noise, glare, etc. cause occupant discomfort, health problems and poor performance. A healthy building is one that works well to provide for the intended users and activities.”
Commissioning helps ensure that the building design is realized. Even the best designs will be negatively impacted by construction shortfalls that result in unintended consequences and sub-par performance, if they are not identified and corrected.
Levin makes the point that the design can incorporate all the required elements to create a healthy work environment but if the construction and operational phases of the building aren’t appropriately implemented to reflect the design requirements, building performance and potentially occupant health will be impacted. To this point, the “Indoor Air Quality Handbook”4 discusses the construction process in relation to “Indoor Air Quality Factors in Designing a Healthy Building” and cites a group study to assess the underlying causes of poor IAQ (American Thoracic Society, 1995). This study concluded that the design/bid/build construction process had the “likelihood of contributing to the problem” of poor air quality due to the “separation of responsibility” of the different participants. The construction of a high performance HVAC system requires a variety of subcontractors including mechanical, controls and balancing contractors as well as the finish trades assembling the actual spaces served (patient, operating rooms, laboratories, dormitory and office space, etc.), all under the direction of a general contractor tasked with delivering the final product to a specific schedule. At completion systems are operating. Commissioning is intended to document not only the operation of the systems but more importantly their performance per the contract.
Building stakeholders need to understand that the best designs can fall victim to construction shortfalls without an effective quality assurance function. Third party verification that commissioning provides serves as the quality assurance function in building construction and helps ensure healthy building designs are constructed as intended.