ASHRAE Journal - October 2012 - 58

To better calibrate the commissioning design review process to the design/build delivery method, it is useful to review the logic behind the approach to commissioning design review for design/bid/build projects. Then, an improved commissioning design review process can be developed that better suits design/build projects. Several other stages of the Cx process can be similarly evaluated and optimized to suit design/build projects.

Cost

Savings

Cost to Change

Potential Synergies and Savings Time Occupancy

The Ability to Influence Project Outcomes

Figure 3 shows curves originally developed by the American Society of Civil Engineers that show that the ability to make changes to a project decreases with time, and the cost impacts increase. The curves are general and do not reflect sudden changes that occur with design completion. Figure 3 is the basis for an expanded version with Cx-related information in Figure 4. Figure 3 shows, in generic terms, accepted industry wisdom: the ability to influence a project is greatest at the beginning of the project, before design or construction work has begun (the blue curve). It also shows that the cost to make changes to a project is lowest at the beginning, and increases over time, especially as construction is completed (red curve).

Programming Schematic Design Construction Design Development

Figure 3: Potential to harvest savings from design synergies.6 and 100% design) may be most effective if it occurs prior to the completion of the bridging documents, instead of occurring at 35%. LEED-enhanced commissioning requires design review, “…prior to the mid-construction documents phase and backcheck [of] the … subsequent design submission.”5 This is less stringent than ASHRAE Guideline 0-2005. Therefore, with LEED design reviews, the problem of diminished effectiveness of commissioning reviews may be even more acute. What does it mean to the commissioning effort if the first design review is not performed until 50% CDs, as required by LEED, if the bridging documents on which the design/build effort is bought were long ago completed and procurement of the design/build contract is complete? In many cases, a unique and significant opportunity to verify and document the quality of the project has been missed. On design/build projects, design changes can occur more readily and with lower cost during early construction. This is a double-edged sword. Commissioning firms can leverage this extended ability to influence project outcomes to improve both the commissioning process and final project outcomes. On the other hand, the quality of a project is not embedded in a “locked down” set of documents prior to construction, increasing the risk that project teams may depart from strategies to meet owners’ project requirements well into construction.

Cost and Influence Curves

These generalized curves have been refined in Figure 4 to emphasize that the ability to influence a project drops abruptly when the design is fixed. On design/build projects, this does not occur in one step when the design phase ends. Instead, the first step change occurs at the time the owner issues the design/build request for proposals (RFP), since the bridging documents or pre-specs issued with the design/build RFP typically serve as the reference and basis for the design/build scope and cost throughout the project. The second step change occurs when the design is completed by the design/build entity and becomes fixed. As a result, two steps down are shown in the “Ability to Change” curve: one at the time the pre-spec is issued and another at the time that the design is completed or fixed. Note that the design is not fixed until later in the process, compared to design/bid/build projects. Theoretically, this should make it possible to have greater influence on the design later in the process. But the cost basis for the remainder of design and its construction were fixed at the moment the design/ build contract was awarded. As a result, on many projects, the cost to change has already jumped, and the ability to influence has already dropped substantially, at the time of design/build contract award. As a result, these changes are shown in two steps. Because of the overlap of the design phase with the construction phase, the commissioning process cannot be neatly executed on design/build projects in the terms widely used in industry guidance and green building rating systems. In terms of ASHRAE Guideline 0-2005, the first of the four statistically based quality design reviews (required at 35%, 50%, 95%,
58 ASHRAE Journal

Improving Commissioning: Real-World Examples
Modifications to the Cx process, such as the approaches in the discussion below and the real world changes in the sidebar, Design/Build Net Zero Energy Schools Project, must be thoughtfully anticipated in the commissioning proposal and fee estimating stages. In this sense, design/build projects may be more vulnerable to the risk of the Cx firm expending too much of their fee on early project stages, without enough fee left over to perform the later critical technical work, including hands-on functional performance testing, system tuning, and other subsequent first-year Cx tasks.

OPRs and Basis of Design
On design/build projects there are always changes to the basis of design (BOD) during construction, since the design of
ashrae.org October 2012



ASHRAE Journal - October 2012

Table of Contents for the Digital Edition of ASHRAE Journal - October 2012

ASHRAE Journal - October 2012
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Energy Audits, Improvements in Small Office Buildings
Long-Term Commercial GSHP Performance: Part 4: Installation Costs
Using CO2 to Reduce Refrigerant Charge
Technology Award Case Studies:
Efficient Science Building
Commissioning Design/Build Projects
Standing Columns
Building Sciences
Emerging Technologies
Data Centers
IAQ Applications
Refrigeration Applications
Special Products
Washington Report
People
Engineer's Notebook
Products
Classified Advertising
Advertisers Index
ASHRAE Journal - October 2012 - ASHRAE Journal - October 2012
ASHRAE Journal - October 2012 - Cover2
ASHRAE Journal - October 2012 - 1
ASHRAE Journal - October 2012 - 2
ASHRAE Journal - October 2012 - Contents
ASHRAE Journal - October 2012 - Commentary
ASHRAE Journal - October 2012 - 5
ASHRAE Journal - October 2012 - Industry News
ASHRAE Journal - October 2012 - 7
ASHRAE Journal - October 2012 - 8
ASHRAE Journal - October 2012 - Letters
ASHRAE Journal - October 2012 - Meetings and Shows
ASHRAE Journal - October 2012 - 11
ASHRAE Journal - October 2012 - 12
ASHRAE Journal - October 2012 - 13
ASHRAE Journal - October 2012 - Energy Audits, Improvements in Small Office Buildings
ASHRAE Journal - October 2012 - 15
ASHRAE Journal - October 2012 - 16
ASHRAE Journal - October 2012 - 17
ASHRAE Journal - October 2012 - 18
ASHRAE Journal - October 2012 - 19
ASHRAE Journal - October 2012 - 20
ASHRAE Journal - October 2012 - 21
ASHRAE Journal - October 2012 - 22
ASHRAE Journal - October 2012 - 23
ASHRAE Journal - October 2012 - 24
ASHRAE Journal - October 2012 - 25
ASHRAE Journal - October 2012 - Long-Term Commercial GSHP Performance: Part 4: Installation Costs
ASHRAE Journal - October 2012 - 27
ASHRAE Journal - October 2012 - 28
ASHRAE Journal - October 2012 - 29
ASHRAE Journal - October 2012 - 30
ASHRAE Journal - October 2012 - 31
ASHRAE Journal - October 2012 - 32
ASHRAE Journal - October 2012 - 33
ASHRAE Journal - October 2012 - 34
ASHRAE Journal - October 2012 - 35
ASHRAE Journal - October 2012 - 36
ASHRAE Journal - October 2012 - 37
ASHRAE Journal - October 2012 - Using CO2 to Reduce Refrigerant Charge
ASHRAE Journal - October 2012 - 39
ASHRAE Journal - October 2012 - 40
ASHRAE Journal - October 2012 - 41
ASHRAE Journal - October 2012 - 42
ASHRAE Journal - October 2012 - 43
ASHRAE Journal - October 2012 - 44
ASHRAE Journal - October 2012 - 45
ASHRAE Journal - October 2012 - Efficient Science Building
ASHRAE Journal - October 2012 - 47
ASHRAE Journal - October 2012 - 48
ASHRAE Journal - October 2012 - 49
ASHRAE Journal - October 2012 - 50
ASHRAE Journal - October 2012 - 51
ASHRAE Journal - October 2012 - 52
ASHRAE Journal - October 2012 - 53
ASHRAE Journal - October 2012 - Commissioning Design/Build Projects
ASHRAE Journal - October 2012 - 55
ASHRAE Journal - October 2012 - 56
ASHRAE Journal - October 2012 - 57
ASHRAE Journal - October 2012 - 58
ASHRAE Journal - October 2012 - 59
ASHRAE Journal - October 2012 - 60
ASHRAE Journal - October 2012 - 61
ASHRAE Journal - October 2012 - 62
ASHRAE Journal - October 2012 - 63
ASHRAE Journal - October 2012 - 64
ASHRAE Journal - October 2012 - 65
ASHRAE Journal - October 2012 - Building Sciences
ASHRAE Journal - October 2012 - 67
ASHRAE Journal - October 2012 - 68
ASHRAE Journal - October 2012 - 69
ASHRAE Journal - October 2012 - 70
ASHRAE Journal - October 2012 - 71
ASHRAE Journal - October 2012 - 72
ASHRAE Journal - October 2012 - 73
ASHRAE Journal - October 2012 - 74
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ASHRAE Journal - October 2012 - 80
ASHRAE Journal - October 2012 - HR1
ASHRAE Journal - October 2012 - HR2
ASHRAE Journal - October 2012 - HR3
ASHRAE Journal - October 2012 - HR4
ASHRAE Journal - October 2012 - HR5
ASHRAE Journal - October 2012 - HR6
ASHRAE Journal - October 2012 - HR7
ASHRAE Journal - October 2012 - HR8
ASHRAE Journal - October 2012 - HR9
ASHRAE Journal - October 2012 - HR10
ASHRAE Journal - October 2012 - HR11
ASHRAE Journal - October 2012 - HR12
ASHRAE Journal - October 2012 - HR13
ASHRAE Journal - October 2012 - HR14
ASHRAE Journal - October 2012 - HR15
ASHRAE Journal - October 2012 - HR16
ASHRAE Journal - October 2012 - HR17
ASHRAE Journal - October 2012 - HR18
ASHRAE Journal - October 2012 - HR19
ASHRAE Journal - October 2012 - HR20
ASHRAE Journal - October 2012 - HR21
ASHRAE Journal - October 2012 - HR22
ASHRAE Journal - October 2012 - HR23
ASHRAE Journal - October 2012 - HR24
ASHRAE Journal - October 2012 - HR25
ASHRAE Journal - October 2012 - HR26
ASHRAE Journal - October 2012 - HR27
ASHRAE Journal - October 2012 - HR28
ASHRAE Journal - October 2012 - HR29
ASHRAE Journal - October 2012 - HR30
ASHRAE Journal - October 2012 - HR31
ASHRAE Journal - October 2012 - HR32
ASHRAE Journal - October 2012 - Emerging Technologies
ASHRAE Journal - October 2012 - 82
ASHRAE Journal - October 2012 - 83
ASHRAE Journal - October 2012 - 84
ASHRAE Journal - October 2012 - 85
ASHRAE Journal - October 2012 - Data Centers
ASHRAE Journal - October 2012 - 87
ASHRAE Journal - October 2012 - 88
ASHRAE Journal - October 2012 - 89
ASHRAE Journal - October 2012 - 90
ASHRAE Journal - October 2012 - 91
ASHRAE Journal - October 2012 - IAQ Applications
ASHRAE Journal - October 2012 - 93
ASHRAE Journal - October 2012 - Refrigeration Applications
ASHRAE Journal - October 2012 - 95
ASHRAE Journal - October 2012 - Special Products
ASHRAE Journal - October 2012 - 97
ASHRAE Journal - October 2012 - Washington Report
ASHRAE Journal - October 2012 - People
ASHRAE Journal - October 2012 - Engineer's Notebook
ASHRAE Journal - October 2012 - 101
ASHRAE Journal - October 2012 - Products
ASHRAE Journal - October 2012 - Classified Advertising
ASHRAE Journal - October 2012 - Advertisers Index
ASHRAE Journal - October 2012 - Cover3
ASHRAE Journal - October 2012 - Cover4
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