ENGINEERING MANUAL OF AUTOMATIC CONTROL
INDOOR AIR QUALITY FUNDAMENTALS
164
ASHRAE GUIDELINE 1-1989
ASHRAE Guideline 1-1989 for commissioning HVAC
systems defines commissioning as “documenting and
verifying the performance of HVAC systems so that systems
operate in conformity with the design intent.” This
guideline, in conjunction with ASHRAE Standard 62-1989,
is a major tool for eliminating IAQ problems. The
commissioning guideline, if implemented, requires system
design and construction processes to ensure and facilitate
implementing the verification process.
The commissioning process starts in the program
development phase with owner buy in and continues throughout
the schematic, design development, and construction phases
of the pre-acceptance phase. The process includes clearly
defined additional contractor responsibilities. Following the
process during the preacceptance phase allows the acceptance
phase to accomplish the desired goals.
The design phases of the commissioning process ensure that
the systems will perform their intended functions. The
construction phase ensures that the systems are installed to
deliver the design. The acceptance phase of the process
demonstrates that the systems work as designed. Documentation
requirements of the process ensure that the building operators
know the design intent of the systems and how they are to be
operated. This process is intended to ensure that owner changes
are recommissioned.
The documentation, required by both ASHRAE Standard
62-1989 and Guideline 1-1989, provides the information
necessary for proper operation and maintenance of the HVAC
systems. The commissioning process requires the involvement
of operating and maintenance personnel in the Acceptance
process to ensure understanding of the design intent and
operational requirements of the systems. Personnel turnover
requires extensive additional training.
Assuming adequate funding of the operations and
maintenance staff, the systems will deliver the design
performance throughout the intended life cycle. Any alternations
required by changes in occupancy requirements need to be
correctly integrated into the system design through the use of a
post commissioning process.
INDOOR AIR QUALITY CONTROL APPLICATIONS
The following control system drawings appear fairly simple
because they illustrate hardware only. The triangles represent
physical connections to a DDC control panel. The related
control functions are all in software programs and need to be
shown on graphic displays for the engineer and building
operator to visualize system operation. Refer to the OPERATOR
INTERFACE and GRAPHIC DISPLAYS topics for a
discussion of a typical operator interface.
For additional information on related control applications
and DDC, refer to the following manual sections of this manual:
— Air Handling System Control Applications
— Building Airflow System Control Applications
— Microprocessor-Based/DDC Fundamentals
GENERAL
To provide appropriate IAQ it is essential to maintain the
building pressure slightly positive to prevent infiltration.
Minimum and maximum air flows must be maintained to assure
proper air distribution and internal pressurization zones.
Terminal regulated air volume control of the supply fan should
match the output to the load with a minimum input of energy.
Use of Direct Digital Control (DDC) and related software
capabilities can be used to provide control and provide
information to the operator to permit better IAQ control and
operator comprehension.
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