AIR CONDITIONING PROJECT DEVELOPMENT
Basic Steps in Development
The basic steps in the development and use of a large air conditioning system are the design, construction,
commissioning, operation, energy efficiency upgrading, and maintenance. Figure 1.4 is a
diagram which outlines the relationship between these steps and the parties involved. The owner
sets the criteria and the requirements. Design professionals in mechanical engineering consulting
firms design the air conditioning system and prepare the design documents. Manufacturers supply
the equipment, instruments, and materials. Contractors install and construct the air conditioning
system. After construction, the air conditioning system is commissioned by a team, and then it is
handed over to the operation and maintenance group of the property management for daily operation.
Following a certain period of operation, an energy service company (ESCO) may often be
required to upgrade the energy efficiency of the HVAC&R system (energy retrofit).
Design-Bid and Design-Build
There are two types of project development: design-bid and design-build. A design-bid project
separates the design and installation responsibilities, whereas in a design-build project, engineering
is done by the installing contractor. Some reasons for a design-build are that the project is too small
to retain an engineering consultant, or that there is insufficient time to go through the normal
design-bid procedures.
According to Bengard (1999), the main advantages of design-build include established firm
price early, single-source responsibility, accelerated project delivery, and performance guarantees.
The market has experienced nearly 300 percent domestic growth since 1986.
The Goal—An Environmentally Friendlier, Energy-Efficient, and Cost-Effective HVAC&R System
The goal is to provide an HVAC&R system which is environmentally friendlier, energy-efficient,
and cost-effective as follows:
● Effectively control indoor environmental parameters, usually to keep temperature and humidity
within required limits.
● Provide an adequate amount of outdoor ventilation air and an acceptable indoor air quality.
● Use energy-efficient equipment and HVAC&R systems.
● Minimize ozone depletion and the global warming effect.
● Select cost-effective components and systems.
● Ensure proper maintenance, easy after-hour access, and necessary fire protection and smoke control
systems.
Major HVAC&R Problems
1. Poor indoor air quality (IAQ)—sick building syndrome. Poor indoor air quality causes the
sick building syndrome. The National Institute of Occupational Safety and Health (NIOSH) in 1990
reported that between 1971 and 1988, 529 field investigations found that lack of outdoor air, improper
use, and poor operation and maintenance of HVAC&R systems were responsible for more
than one-half of sick building syndrome incidents. Field investigations found that 20 to 30 percent
of the buildings had poor-air-quality problems. Sick building syndrome is covered in detail in
Chap. 4.
2. Updated technology. In recent years, there has been a rapid change in the technology of air
conditioning. Various types of VAV systems, air and water economizer, heat recovery, thermal storage,
desiccant dehumidification, variable-speed drives, and DDC devices have become more effective
and more advanced for energy efficiency. Many HVAC&R designers and operators are not
properly equipped to apply and use these systems. Unfortunately, these sophisticated systems are
managed, constructed, and operated under the same budget and schedule constraints as the less
sophisticated systems. After years of operation, most HVAC&R equipment and controls need to be
upgraded for energy efficiency.
3. Insufficient communication between design professionals, construction groups, and operators.
Effective operation requires a knowledgeable operator to make adjustments if necessary. The operator
will operate the system at his or her level of understanding. If adequate operating and maintenance
documents are not provided by the designer and the contractor for the operator, the
HVAC&R system may not be operated according to the designer’s intentions.
4. Overlooked commissioning. Commissioning means testing and balancing all systems, functional
testing and adjusting of components and the integrated system, and adjusting and tuning the
direct digital controls. An air conditioning system is different from the manufacturing products having
models and prototypes. All the defects and errors of the prototypes can be checked and corrected
during their individual tests, but the more complicated HVAC&R system, as constructed and
installed, is the end product. Therefore, proper commissioning, which permits the system to perform
as specified in the design documents, is extremely important. Unfortunately, the specifications
seldom clearly designate competent technicians for the responsibility of commissioning the entire
integrated system. Commissioning is covered in detail in Chap. 32.
5. Reluctant to try innovative approaches. In addition to Coad’s paper, a survey was conducted
by the American Consulting Engineers Council (ACEC) in 1995. For the 985 engineering firms that
responded out of about 5500 firms total, there were 522 legal claims filed against them, 49 percent
of suits resolved without payment. Among the 522 legal claims, 9 percent were filed against mechanical
engineering firms. Fifty-two percent of 1995 legal claims were filed by owners, and
13 percent were filed by contractors or subcontractors.
Because of the legal claims, insurance companies discourage innovation, and engineering
consulting firms are reluctant to try innovative techniques. Twenty-one percent of these firms said
they were very much reluctant, 61 percent said they were somewhat affected, and 25 percent said
they were a little affected. Support and encouragement must be given to engineering firms for carefully
developed innovative approaches to projects. In addition to the ASHRAE Technology Awards,
more HVAC&R innovative awards should be established in large cities in the United States to
promote innovative approaches.
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