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Overview
Buildings are seldom delivered to owners in full working condition. Most existing buildings accumulate
persistent energy-performance and comfort problems to which "band aid" solutions are applied. Comprehensive
commissioning of new buildings has been shown to greatly reduce the incidence of nonworking systems, and
tune-ups and recommissioning of existing buildings typically improve comfort as well as reducing energy
use by 15 to 20 percent. But even these "fixes" are not permanent, and most buildings drift, often
"invisibly," to lower performance levels over time, indicating a need for ongoing performance monitoring
and fault detection and diagnosis during routine operation.
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- Technical Highlights
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A study by the Energy Center of Wisconsin (1998) found that 81 percent of
building owners surveyed encountered problems with new heating and air conditioning systems. Another study of 60
buildings by Ernest Orlando Lawrence Berkeley National Laboratory (LBNL) found that half of building owners surveyed
were experiencing controls problems, 40 percent had heating, ventilation and air conditioning (HVAC) equipment
problems, 15 percent had missing equipment, and 25 percent had energy management systems, economizers, and/or variable
speed drives that were not functioning properly.
It has been shown that these problems can be avoided if buildings are properly commissioned. Commissioning has many
definitions; in this project, we define commissioning as "a set of services intended to ensure and document quality
building system performance and facilitate building operation, yielding improved owner/occupant satisfaction." This
process enables buildings to operate as designed or according to their "design intent.". However, a clear statement
of design intent is often lacking.
The principal concern of design engineers is to ensure that installed systems can provide for occupant comfort under
all reasonably expected conditions. This concern often results in an excessive equipment sizing "safety factor."
Moreover, most large buildings must be designed so they can simultaneously provide heating and cooling, which are
each required during at least part of the year. Recurring comfort problems and inefficient system operation typically
result from the combination of oversized components, simultaneous heating and cooling capabilities, and the natural
response of building operators to rapidly address hot and cold calls.
Integrated Commissioning and Diagnostics Brochures:
Experienced commissioning professionals have their own sets of procedures and tests for the commissioning process.
ASHRAE Guideline 1 describes the commissioning
process in considerable detail but lacks practical information on specific tests and procedures. This project is developing
a functional test guide and digital control design guide (with new tests) to address this gap. These guides should make
it much easier for additional professionals and firms to begin providing high-quality building commissioning services.
Tasks:
The objective of this task is to develop a functional test guide (FT Guide) that can be used in concert with
Pacific Gas & Electric (PG&E) company's Commissioning Test Protocol Library (CTPL).
Retro-commissioning of existing buildings emphasizes finding and fixing problems and improving HVAC operating efficiency.
This project is addressing the need to make practitioners aware of tools that are available to help in the "problem-finding"
process, as well as developing improved approaches for acquiring and using building performance data to help identify
problems and determine how to fix them correctly.
Tasks:
The objective of this task is to evaluate current diagnostic procedures and tools that can be used by building professionals to
determine when building system performance has degraded to the point that efficiency or comfort costs merit replacement or repair.
The objective of this task is to develop a procedure for assessing the economic viability of using older EMCS systems for monitoring,
including criteria for using an EMCS "as is," upgrading it, or installing a separate monitoring system.
The objective of this task is to develop and deploy high-speed electrical load monitoring that can provide component-specific load
information from a centralized location (motor-control center, HVAC service entrance, or whole building), thereby substantially
reducing the cost of obtaining this information.
The objective of this task is to incorporate occupant feedback into building system diagnostics so that the efficiency and effectiveness
of building operations can be improved.
The objective of this task is to investigate the reasons that the performance of mechanical systems, including system retrofits, degrade
over time and to recommend intervals at which testing should be performed. Further objectives are to assess the relative costs and benefits
of continuous monitoring and periodic testing.
This project aims to develop advanced commissioning methods using whole-building simulation programs
(AirModel: 216.3K, 8 pp,
EnergyPlus),
and more detailed component models to begin a transition to automated diagnostics. Ultimately, automated systems warn users of comfort
and efficiency problems and point out remedies.
Tasks:
The aim is to develop whole-building-level functional test procedures based on energy simulation programs in order
to verify that the building is capable of delivering the performance expected by the designers.
Tune-up procedures based on calibrated simulation have been demonstrated to reduce HVAC operating costs
significantly but, in their current form, they are costly to implement and require personnel with special
skills. The aim of this task is to make calibrated simulation a practical tool for building tune-ups by
significantly reducing the time and skill level required for their use.
The objective of this task is to implement and test component-level functional testing and performance monitoring
procedures for HVAC systems. The approach is to predict the expected performance of particular items of HVAC
equipment. A significant difference between the predicted and observed performance indicates the presence of a
fault. Relevant operating data are then displayed so that the operator can confirm the presence of the fault and
take steps to diagnose its cause so that it can be remedied.
Contact:
David Claridge, Texas A&M University (TAMU), (979) 845-1280
