ASHRAE Journal - December 2013 - 44

technical feature

Participating in the startup scheduling process to ensure that all systems are installed, started, and completed
in proper sequence.
Preparing and maintaining an issue log book that
documents deficiencies, issues, questions, and retesting
requirements/activities.
GC/CM: The general contractor/construction manager must prepare an accurate, critical-path construction schedule that shows step-by-step how the building
must be constructed. The GC/CM is also responsible for
creating and coordinating the schedule of construction
events-and ensuring that all subcontractors perform
their work in compliance with the final project drawings
and specifications.
The construction schedule requires input from all
project trades, subconsultants, and subcontractors.
A proper schedule must accurately account for every
phase of the construction process. The schedule must
also list the various line items that make up the project's
critical-path milestones-none of which can begin until
the preceding task is completed.

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D ecem ber 2013

Consider this sample list of milestones: To ensure the
construction phase is properly completed, the Cx Plan
should list critical-path milestones for the HVAC contractor such as:
Install equipment.
Wire equipment to proper electrical panels.
Connect equipment to proper ducts and pipes.
Flush and clean pipes; fill with proper fluid.
Start equipment and verify proper operation.
Paint walls.
Install wall thermostats and temperature sensors.
Install ceiling grids.
Install diffusers, registers, and filter elements.
Perform point-to-point tests on all control systems;
verify graphics, and calibrate sensors.
Complete system testing, adjusting, and balancing.
Conduct FPTs to verify systems operate as specified.
Complete final, third-party FPTs.
Note that each critical-path milestone depends on the
previous one. For example, you can't test, adjust, and balance systems until all controls systems are working properly. And control systems can't be tested until thermostats are installed and systems are wired and filled with
hydronic fluids. In turn, systems can't be test-run until
they're connected to the appropriate pipes and ducts.
Many of us see projects for which the mechanical and
electrical construction schedules are created without the
benefit of critical-path thinking. But when the project
falls behind schedule, the completion date almost never
changes, which means the project's final stages compress to the point where all trades are working in the
same space at the same time.
This kind of frenzied rush to completion seldom delivers a building that works properly. Too often, systems
aren't even properly tested until the occupants move
in. The result? Unhappy occupants and a dissatisfied
owner. So, it's vital that the GC/CM to prepare an accurate critical-path schedule that incorporates enough
time for all contractors to properly check their systems-
and enough time to accommodate the Cx process.
To support the GC/CM in creating the critical-path
schedule, the Cx Plan should list specific projected time
durations for every step in the Cx process. Don't forget
that most pre-functional tests and inspections can be performed concurrently with the project's mechanical/electrical/plumbing tasks. In contrast, FPTs are critical-path
tasks that cannot be performed concurrently with other
functions.

ASHRAE Journal - December 2013

Table of Contents for the Digital Edition of ASHRAE Journal - December 2013