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Commissioning CORE & SHELL and Tenant Fit-Out Projects

The seed of a fruitful project is in agreeing on the core vision.

It is exciting to see that the benefits of commissioning are being realized by more and more commercial real estate developers and their tenants. A traditional speculative office building presents special challenges for the commissioning process. In the commercial real estate market many office buildings are constructed as a Core & Shell (C&S) by the developer with customized Tenant Fit-Out (TFO) of occupied spaces as they are leased.

This is such a significant portion of the new building industry that some of the first special programs in the United States Green Building Council’s LEED® (Leadership in Energy and Environmental Design) rating system were developed for Core & Shell Development and Commercial Interiors (Tenant Fit-Out) projects. Whether or not a project is registered in the LEED program, commissioning can help the developer realize a more successful project and more a profitable investment.

In this and subsequent columns I intend to explore the unique aspects of commissioning Core & Shell/Tenant Fit-Out new construction projects. This month will cover the always-critical Owner’s Project Requirements/Design Intent documentation.

The Core Of C&S

The C&S portion of a new project is often designed and constructed without knowing exactly who or what activities will occupy all parts of the finished building. As such, the developer must speculate about what features will be most attractive to potential tenants. In addition to deciding on types of finishes to put on the outside Shell of the building and on the inside Core (e.g., public lobbies, restrooms, elevators, etc.), the developer needs to make decisions regarding the capacities and qualities of the mechanical, electrical, and life safety systems.

As with any project type, the Owner’s Project Requirements (OPR) or Design Intent Document (DID) is the foundation on which commissioning is built. For a Core & Shell project, the OPR/DID is especially beneficial to the real estate developer. Not only is it a document which defines the system performance goals for the design and construction team, it also serves as a valuable tool for communicating and negotiating with potential tenants.

I recommend that the OPR/DID contain the following elements, as appropriate:

  • Summer and winter outdoor temperature and relative humidity design conditions

  • Summer and winter indoor temperature and relative humidity design conditions

  • Indoor air quality (CFM of outside air per square foot, maximum CO2 concentrations, or air changes per hour of outside air)

  • Year-round cooling loop capacity allowance (square foot per ton) for tenant spot cooling requirements

  • Indoor lighting density allowance (watts per square foot) for tenant spaces

  • Indoor electrical plug load allowance (watts per square foot) for tenant spaces

  • Occupant density allowance (square feet per person) for tenant spaces

  • Backup power (generator) allowance (watts per square foot per hour) for tenant spaces

  • Infrastructure system redundancy provisions and/or reliability metrics

In addition, it is critical to define exactly where the C&S systems stop and the TFO systems start. For example, does the C&S project include HVAC terminal units (variable air volume boxes, heat pumps, perimeter radiation, etc.) for the TFO spaces or just valved or dampered stub-outs from piping or ductwork mains? If TFO terminal units are to be provided by the C&S project, what is their size and density (cooling/heating capacity and square feet per terminal unit)?

Moving on to TFO

With this level of detail in hand, the developer and future tenant can share a clear understanding of what is being provided by the C&S part of the building. If the tenant needs more, the TFO portion of the project can provide supplemental cooling, ventilation, and/or electrical power. Having the OPR/DID defined prior to the signing of lease agreements and before Tenant Fit-Out design and construction starts can help avoid costly misunderstandings and potential disappointments after the tenant moves in.

Because a Core & Shell project is most often contracted separately from its associated Tenant Fit-Out projects, it is important to have each Tenant Fit-Out project OPR/DID documented separately for commissioning and long term operational purposes. The Tenant Fit-Out OPR/DID can draw heavily from the Core & Shell OPR/DID but will often have special requirements unique to the incoming building users. These may include temperature and/or humidity levels, special exhaust and associated makeup air requirements, system redundancy expectations, etc.

The single Core & Shell OPR/DID and multiple Tenant Fit-Out OPR/DIDs can be consolidated into a single reference document at the end of construction. A consolidated OPR/DID is an extremely valuable resource for on-going operations, subsequent leasing agreements, and the inevitable future renovations in the building. The facility operations and maintenance staff will know what each tenant’s needs and expectations are, and renovation design teams will know what the existing systems are capable of doing in order to determine if they can meet the OPR/DID criteria for the next Tenant Fit-Out project.


Commissioning: Getting It Right

Engineered Systems, May, 2007

Rebecca Ellis, PE, LEED AP, CCP, CxA
Questions & Solutions Engineering
1079 Falls Curve
Chaska, MN  55318