Commissioning: Retrocommissioning (Energy Engineering)

Abstract

This entry examines the practice of commissioning in existing buildings, or retrocommissioning. It provides a definition and a practical understanding of the retrocommissioning process, outlines the energy and nonenergy benefits that result, and examines the link between retrocommissioning and maintenance activities. It also explains the relationship between retrocommissioning and the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) certification process and the energy conservation outcomes of retrocommissioning application.

INTRODUCTION

Retrocommissioning is a popular method for reducing energy and operating costs in all types of large, existing buildings. This popularity is due largely to the fact that retrocommissioning pays for itself quickly through the energy and operating cost reductions it produces. Aside from its abundant energy conservation potential, it also offers additional benefits. Depending upon the nature of its application, retrocommissioning can decrease demand maintenance frequency and occupant comfort complaints, improve indoor air quality, and enhance building maintenance staff productivity.

Retrocommissioning is not a one-time event in the life of a building. Rather, its long-term benefits are better realized through a continuous or ongoing approach that is supported by appropriate maintenance activities, throughout the life of a building.


This entry provides a definition of retrocommissioning and how it differs from commissioning and recommissioning. It offers an overview of the retrocommissioning process, the energy and nonenergy benefits, methods used to maintain those benefits, and some typical results of this application. Although a comprehensive retrocommissioning project could extend to all of a building’s components, such as operating equipment and systems, core, shell, envelope, and finishes, this discussion focuses on those issues that impact energy utilization, operating costs, and the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) certification program.

DEFINING RETROCOMMISSIONING

Where commissioning refers to a function that occurs during the construction of a building, to ensure that a new construction project meets design intent, and recommissioning is the periodic reapplication of that same function during the life of a previously commissioned facility, retrocommissioning is essentially the commissioning of an existing building that was never commissioned. All three terms refer to a systematic quality management process designed to ensure that building systems and equipment, whether or not they consume energy, function as intended by design, or based upon current use requirements.

Historically, commissioning has not been widely embraced in the new construction industry and its application is currently limited. This is due largely to the lack of hard data concerning the benefits of commissioning and a perception that its application adds unnecessary costs to a construction project. The result is an inventory of buildings that were never commissioned, many of which suffer from undiscovered deficiencies left over from the construction phase. This unfortunate circumstance is becoming more evident to building owners, developers, designers, and contractors and the practice of commissioning, recommissioning, and retrocommissioning is now receiving increased attention.

Retrocommissioning is widely regarded as a more challenging activity than commissioning or recommissioning. This is the case because buildings that were not commissioned during the construction phase generally lack comprehensive or updated reference documentation that is critical to understanding the design and operating intent of building components and systems. Without this up-to-date documentation, the retrocommissioning provider must gather information and perform functional testing “retroactively” to determine the existing performance characteristics for building systems, and then make adjustments to compensate for changes in building configuration and usage requirements. When complete, aretrocommissioning project should provide new and updated documentation sufficient for future recommissioning.

Understandably, and depending upon the age of the building, much could have changed since original construction. This can include changes to the physical configuration of occupied spaces, the addition of equipment and fixtures, new operating sequences, and altered performance characteristics of installed equipment. In large facilities with complex building systems, understanding and documenting these changes can be a time consuming and expensive process. For this reason, many retrocommissioning projects tend to focus only on building systems that have a history of chronic performance problems or those systems that have an impact on energy or operating costs. Projects such as these are often referred to as building tune-ups and they focus more on the effective and efficient operation of a building, rather than static design issues and equipment retrofits. Heating, ventilating and air conditioning equipment, related mechanical and electrical systems, building management and control systems, lighting systems, domestic water systems, and the building envelope are all good candidates for this approach.

THE RETROCOMMISSIONING PROCESS

Retrocommissioning normally includes four phases of work. These phases are used to determine the available opportunities on a broad scale, put a plan in place to address those opportunities, implement that plan, and document results. Although each phase in the retrocommissioning process may require additional components of work depending upon project objectives or complexity of the tasks, most projects follow similar sequences. For the purposes of this discussion, it is generally accepted that a retrocommissioning project will include the following steps:

• A preliminary evaluation of building systems and operating characteristics designed to gather initial data and determine potential project requirements and project scope

• A detailed assessment and project development phase where comprehensive observation, monitoring, testing, and project design takes place

• A project implementation phase where chosen recommendations are implemented

• A documentation and training phase where post-project building characteristics, operating procedures, and equipment conditions are documented, and building operator training is conducted

During the preliminary evaluation stage, the provider will determine the general nature of the project and attempt to come to some preliminary conclusions regarding potential solutions. This phase includes discussions concerning the owner’s project requirements, project goals, and the analysis of available data concerning building design and design intent. Current usage requirements, equipment inventories, energy consumption and costs, and occupant complaint histories are examined. Demand maintenance evaluation, equipment performance issues, operating staff interviews, and first hand observation of building system conditions are also carried out. At the conclusion of the preliminary evaluation the retrocommissioning provider should have sufficient information to approximate energy and operating cost reductions the project could produce, and the costs to deliver those reductions. This information is normally summated in a preliminary evaluation report.

The detailed assessment and project development stage of a retrocommissioning project is normally the phase where more definitive conclusions are reached regarding the current operating performance of equipment and systems within the building. At this time, monitoring devices are installed on various pieces of equipment and in occupied spaces, in order to collect and verify current operating data. Information about occupancy patterns, equipment scheduling, control sequences, temperatures, pressures, flows and loads can provide valuable insights into building and systems performance.

In many cases the building will be controlled by a building management system (BMS) or direct digital control (DDC) system capable of collecting data on equipment operation. This data can be extremely useful for populating trend logs that provide real time information about building operation. The degree to which a BMS is capable of collecting this data will determine the need for independent or standalone data collection devices.

The detailed assessment and project development phase is also the time when the condition and efficiency ratings of building equipment is evaluated, and utility cost, consumption and demand profiles are confirmed. At this point equipment demand maintenance histories are reviewed for trends, maintenance and operation procedures are examined, and building operator skills assessed. At the completion of this phase, the provider should have a detailed understanding of the current operating parameters of building systems and equipment, and will have identified the specific strategies and measures to be used in mitigating equipment performance issues and reducing energy and operating costs. The provider will typically provide a detailed assessment and project development report at this stage. This report will usually contain all the relevant information required to make a decision on the financial merits of the project.

During the third phase of a retrocommissioning project the recommended measures that the owner has selected are implemented. This stage of the project is guided by the implementation plan developed during the project development phase. Although it is typical for the provider to manage the quality of the implementation process, individual components of the work are usually performed by third party providers who have specific expertise related to each of the measure requirements. The implementation stage is an excellent time for building maintenance and operations staff to become more familiar with the operational and equipment improvements taking place in their building. Their participation in this phase of the work can be a valuable learning opportunity because it offers a hands-on understanding of the process and a foundation for ongoing commissioning activities in the future. At the conclusion of project implementation, the retrocommissioning provider will have completed the recommended measures outlined in the implementation plan, and will have put in place any project monitoring requirements that were included in that plan.

The final stage of retrocommissioning includes the preparation of as-built documentation concerning design and performance changes made as part of the implementation plan. This should provide the owner with all documentation associated with functional testing and load calculations, along with updates to drawings, specifications, and changes to equipment operation. Information concerning system set-points, operating schedules, operations and maintenance manuals, and any additional changes or alterations made during project implementation should also be provided.

It is also normal at this time to implement any project outcome monitoring requirements and to initiate maintenance and operations training that was identified during the project development phase. Aside from contractual obligations that may require return visits to perform follow-up training or provide project monitoring reports, the retrocommissioning provider’s duties are generally complete at this point.

Although the four phases of work described here are widely accepted as standard for core retrocommissioning applications, variations are not uncommon. Unique site conditions, project outcome expectations, the skill level of existing building operations staff, and other factors can all have an impact on sequence and content. In some cases, the relationship past the point of project completion continues because the owner perceives a value in retaining the provider in a project-monitoring capacity. Some providers offer a comprehensive package of services that “support” the owner’s operations staff in their efforts to continuously commission their building beyond project completion. Still others will provide a periodic review and reporting function designed to validate projected energy and operational improvements that occurred as a result of the retrocommissioning project. The value and selection of these additional services will always be unique to the circumstances of the project.

RETROCOMMISSIONING AS AN ENERGY CONSERVATION TOOL

Retrocommissioning has the potential to produce large reductions in energy use at a relatively low cost. For this reason, it is becoming a popular cost avoidance tool among building owners and operators. To understand why these energy savings are available it is must be understood that most existing buildings were not commissioned when they were constructed. As a consequence, many buildings do not meet design intent at completion. The result is a large inventory of buildings that are likely to be operating inefficiently. That is not to say that construction projects lack quality control or specification compliance. Simply, it suggests that the historical effectiveness of the quality control mechanism during the construction process is insufficient to fully ensure that a new building operates in accordance with design intent. When factors such as building age, traditionally low investments in maintenance staff training, changes in space configuration, and multiple adjustments to building systems over time are added to that equation, the result is often a building that fails to operate in an energy efficient manner.

Unfortunately, buildings that were not commissioned during construction will have the greatest degree of problems in the very systems that are the most responsible for energy consumption. Heating, ventilating and air conditioning systems; supporting mechanical and electrical equipment; and the controls that govern the operation of these systems play a critical role in the energy profile of any building. In the absence of a comprehensive quality management process during the construction, much can be overlooked. It is not unusual to discover:

• Pumps installed backwards

• Fans and terminal boxes that produce incorrect air volumes

• Missing dampers and damper motors

• Economizers that are incorrectly sequenced

• Disconnected valve actuators

• Systems or equipment that is undersized or oversized

• Inappropriate building management and control strategies

• Simultaneous heating and cooling

• Lighting systems that remain active past occupancy

• Voids in the building envelope

• Equipment or devices that are missing altogether

Although these sort of static deficiencies are not uncommon, they are not the only source for concern. Another, and perhaps more important factor, is the impact that a lack of effective documentation and training at building turnover can have. Recognizing that the cost to operate a building is significantly greater over its lifetime than the cost of original construction, it must be accepted that operations and maintenance plays a critical role in a lifecycle cost analysis. Projects that lack sufficient documentation and allowances for training at completion simply have a greater likelihood for inefficient operation. Unfortunately poor documentation and ineffective training is more the rule than the exception.

Overall, retrocommissioning is a powerful tool for improving energy efficiency and building operator effectiveness. In a 2004 study sponsored by the U.S. Department of Energy[1] that focused on the results of retrocommissioning applications across the country, it was found that, on average, each building had a total of 32 deficiencies. In one building, a total of 640 deficiencies were discovered. Of all the deficiencies found as a result of this study, 85% were related to heating, ventilating, and air conditioning systems. Often, deficiencies like these go undetected for years, causing repeated comfort complaints from building occupants, wasting energy, and increasing the rates of equipment failure and repair costs. Given the frequency of these sorts of deficiencies in new buildings, it should not be surprising that building owners are reaping large energy conservation and operating cost rewards through the application of retrocommissioning.

Although the magnitude of savings that retrocommissioning can produce is dependent on the types of deficiencies discovered, the research sponsored by the U.S. Department of Energy[1] suggests that energy savings can be very significant. In that same 2004 study, which took into account the results from 106 separate projects, energy savings of between 7 and 29% were reported, with paybacks ranging from 0.2 to 2.1 years. Additional data from that study is shown in Fig. 1 below.

NONENERGY BENEFITS OF RETROCOMMISSIONING

In addition to the reasonably quantifiable energy conservation benefits of retrocommissioning, there exists a group of nonenergy benefits that are more difficult to quantify. Although these benefits will have differing values depending upon the type of building and owner motivations, they are none the less important considerations in a decision to proceed with a retrocommissioning project. For example, in the 2004 U.S. Department of Energy[1] study of existing building commissioning, it was discovered that although energy conservation was a primary motivator for 94% of the projects reviewed, a surprising number of projects were motivated by none-nergy benefits. See Fig. 2 below.

As evidenced by this study, issues such as systems performance, improved thermal comfort, and indoor air quality were all deemed to be important factors in choosing to proceed with a retrocommissioning project.

These benefits are difficult to quantify in monetary terms because they are the outcomes of equipment operation or building performance. However, when they are viewed in the converse, their value becomes clearer. For instance, in an office building where the loss of a major tenant can be a costly event to the landlord, maintaining a healthy, comfortable, and productive indoor environment is critical from both a business perspective and a liability standpoint. The value of the benefit in this case would accrue to the avoided costs of finding a new tenant for a vacated space and the avoidance of potential litigation costs associated with an indoor air quality problem.

In certain types of buildings, energy conservation investments can produce other types of financial benefits. An example of this would be the relationship between reductions in operating costs and asset valuation in the commercial real estate industry. According to the ENERGY STAR® Program, every dollar invested in energy efficiency, at a 20%-30% saving rate, is equivalent to increasing net operating income by 3%-4%, and Net Asset Value by $2.50-$3.75. Comparisons like these can be made for all kinds of buildings in all major industries.

An additional nonenergy benefit of retrocommissioning can be derived from improvements in productivity for maintenance and operations staff. This benefit can be sourced from the reductions in occupant comfort complaints that result from improvements in building systems performance. With this reduction comes improvement in productivity or the amount of time that existing staff can expend on deferred maintenance items, other specific activities that impact energy use, or training opportunities that support those functions. Once again, these improvements are difficult to quantify in monetary terms and studies to date have failed to produce definitive findings. It is not difficult to accept, however, thatimprovements such as these can only have a positive impact on a building operator’s time and on the overall cost of operations for any building.

RETROCOMMISSIONING AND MAINTENANCE ACTIVITIES

Retrocommissioning can provide a host of benefits in existing buildings, and studies conducted by many respected individuals and organizations supports that observation. Maintaining those benefits through the life of a building is, however, largely a function of how well the building is operated and maintained during the post-retrocommission-ing period. It has been revealed through several studies that the quality of maintenance activities will impact the persistence of energy savings, and equally, the nonenergy benefits that are dependent upon equipment performance.

The relationship between maintenance activities and the persistence of the energy and non-energy benefits of retrocommissioning has received considerable attention. In a 2003 study[2] jointly sponsored by the Department of Energy and the California Energy Commission, the researchers noted that energy savings that averaged 41% of total energy used in a building decreased by 17% over two years. These findings also indicated that the long-term persistence of energy savings hinged on the abilities of the building operators to troubleshoot and understand how the systems in the building were supposed to operate.

Units Number of projects Min Bottom 25% Median Average Top 25% Max
Commss.oned ‘ic.lr area fr 100 5,000 85.101 151.000 208,7201 271.05D 1,014.133
Comrrussioning Costs
Total S2003,’butldmg 102 3,214 20.112 33.696 48.442 45,802 478.554
Normalized – excluding nor-er.e-gy impacts. 1 = 1- S2D03m’ 102 0.03 013 0.27 041 0.45 3.86
Nonnalized – onEyfor cases including non-energy impacts. NEts’ 32003,’^ 11 -0 27 0.04 0.17 0.41 045 1.BS
Cx agent fee as percentage of tula commissioning fee % 6 32% 35% 67% 57% 71% 70%
Costs paid by.
Striding owner % 31 0% 32% 50% 47% £0% 100%
Utility (e.g as rebate J % 46 20% 50% 84% 75% 100% 100%
Other (e.g. research grant) % 7 33% 1G0% 100% 00% 100% 103%
Utility rebates (included in above costs) 32003/butlding 46 017 11.832 20.500 23.085 25.000 76.725
as % of total costs % 46 20% 50% 84% 75% 100% 103%
Deficiencies
Per building N umbentiu lo ng 65 0.7 5.0 11 32j 21.0 640.0
Per 100kft2 Number* 1MkfF 65 0.1 2.S 6 24. 18.3 225.6
Measures
Per building Numbetfbu tiding 75 1.0 4.5 9.0 20.3 ie.o 481.0
Per 100M12 N umber* lOOkft1 00 0.1 2.5 5.9 6.SI 12.7 216.6
Total Energy Cost Saving
Raw data (mixed energy pnoes and years) nomina1 Sfbuilding-yr 100 -25.752 11.739 33,629 66.469 75.&40 679,101
Local energy prices S2003ltjuiltfing-yr 100 -26.59 S 13.351 37,376 75.393 60.ei5 1.034,667
Standardized US-average energy prices £2Q33.’buildirg-yr 57 -30.043 14.545 44,629 105.158 08,706 1,778,371
Percent energy bill savings 74 -3% 7% 15% 18% 28% 54%
Normalized Energy Cost Savings
Raw data (mixed energy prices and years) nominal S/fP-v 100 -0.00 0 11 0.24 0.42 0.45 3 63
Local energy prices i^nraiff.vT 100 -0.09 0 11 0.27 0.47| 0 52 4.33
Standardized US-average energy prioe 56 -0.13 0.11 0.26 0.54 0.72 3-23
Monetized non-energy Impacts (one-tinr>e3
Per project 32003/project (tOOOs) 10 -2B1 -31 -17 -4E -11 -1
Normalized by floor area S2003/ft2-yr 10 ■0 55 -0.45 -0.18 -0.26I -0 10 OKI
Energy Savings
Electnqty kWhff-yr 57 -0.7D 0.84 1.7 2 2 2.70 8.73
Percent savings % 46 -5% 5% 9% 11% 15% 30%
Peak electrical power*1 W.’ff” e 01 0.4 0.6 0.7 0.6 1.0
Percent savings % 3 1% 2% 2% 7% 9% 17%
Fuel kBTu-fr-yr 29 -14.2 2.3 6.5 15.8 13.5 209.5
Percent savings % 18 -10% 1% 6% 13% 23% 6714
Thermal (chilled w hot water, steairit kBTU/fr-yr 18 0 32 64 84 122 350
Percent savings It 16 13% 23% 36% 37% 46% 63%
Total kSTUff-yr 57 -15 7 17.0 40.3) 58 357
Percent savings % 4e -7% 15% 10% 29% 57%
Payback Times [undtscounted]
Raw data (mixed energy prices and years) years 99 -1.5 0.4 1.0 2.1 2.0 20.7
Local energy prices and inflalfor-corraoted cx yea’s 99 -1.5 0.3 1.0 2.1 2 4 20.1
Standardized U.S. energy prices and inflation-coneoted cx costs years 50 -1.0 0.2 0.7 17 Z1 104

* Norvenergy impacts (NEis] include ncreases or decreases in first or operating costs due to changes in maintenance costs, contractor callbacks, equipment life. and ” Most are averaged over the entire year, hence true “peak” savings are significantly higher than shown here.

Fig. 1 Result summary with quartile analysis—existing buildings.

Reasons for existing building commissioning.

Fig. 2 Reasons for existing building commissioning.

In concluding why retrocommissioning benefits would persist in some applications and not in others, the study observed that persistence was influenced by a group of factors. The most notable of these appeared to be the working environment and operator training. Successful projects, where savings tended to persist, were those with working environments that provided high quality operator training, time to study and optimize building operation, and a management group that was focused on optimizing the performance of the building and reducing energy costs. In addition to the working environment and training, the study concluded that performance tracking and adequate documentation could impact benefit persistence as well. In the case of performance tracking it was suggested that energy use tracking and trend data analysis were important factors for persistence. Proper documentation concerning building equipment and its operating intent could also provide building operators with information on how to effectively operate the building.

Creating benefit persistence through building operator training can have a profound affect on how valuable a retrocommissioning project can be through the life of any building. This factor has been particularly well documented through the experiences at Texas A&M University over a number of years. Since 1993 the school has deployed a process called Continuous Commissioning® in more than 130 large campus buildings and has made training for building operators in this process a cornerstone of its maintenance efforts. The results of this focus have been dramatic, producing maintained energy savings for the school of between 15 and 25%. In a 2001 study conducted under the California Energy Commission’s

Public Interest Energy Research Program and involving ten buildings at Texas A&M, the Continuous Commissioning process was projected to deliver $4,255,000 in energy savings over a four-year projection.1-3-1

Given the magnitude of energy savings and other benefits available from retrocommissioning, and the impact that maintenance functions and training have on the persistence of those savings, it is not difficult to conclude that a well-trained, effective, and supported maintenance program is essential for any building.

RETROCOMMISSIONING AND LEED CERTIFICATION

Commissioning and retrocommissioning have both found their way into the U.S. Green Building Council’s LEED certification and point award process. This clearly illustrates the value that the USGBC places on these processes and provides further evidence that their application can have a positive impact on environmental and energy issues for any building.

The LEED certification process provides award points that encourage “green” building design, construction, and operation. Depending upon award points attained, a building can be ranked as LEED Certified, LEED Silver, LEED Gold, or LEED Platinum. It is important to point out that these award rankings can be achieved only if a new construction project is commissioned or an existing building is retrocommissioned. It is also important to note that in all rankings, LEED places a great deal of emphasis on the very systems in a building that account for the greatest impact on energy costs. This emphasis is similar for commissioning and retrocommissioning, and in many ways these processes, and the intent of the LEED rating system, are functionally complementary. Both have a positive affect on energy consumption, and therefore, a similar impact on the environmental footprint a building will make.

In existing buildings, retrocommissioning is regarded as a cornerstone of the LEED certification process. The LEED points available for existing buildings focus attention on building operations, testing, monitoring, repeated commissioning, and continuous improvement. Points are available for such things as the development of a Building Operations Plan, a commitment to 24 hours of training for building operators each year, performance monitoring of equipment operation and maintenance best practices. It is not coincidental that the most successful retrocommissioning projects encourage and support similar activities.

CONCLUSIONS

Retrocommissioning offers excellent energy conservation and operational improvement opportunities for existing buildings, with minimal investment. It can improve the effectiveness of operations and maintenance staff, provide a group of nonenergy benefits and can assist in the attainment of a LEED certification. However, the most important factor the reader can take away from this section is that commissioning during construction can eliminate many of the problems that owners inherit at the acceptance of their project. Ultimately, as commissioning is more widely adopted in new construction projects, the need for retrocommissioning could be eliminated altogether.

In the meantime, however, retrocommissioning is gaining an impressive following of supporters.

It is encouraging that the Department of Energy, ENERGY STAR®, American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the Association of Energy Engineers, the California Department of General Services, the California Energy Commission, The U.S. Green Building Council, and many others now recognize the impact that this application brings to energy conservation and environmental protection. In California, retrocommissioning has found its way into the State’s Green Building Action Plan by requiring that all buildings 50,000 ft2 and over be retrocommissioned and that periodic recommissioning take place in the following years. In another signal of the value of this application, utilities in California are now offering rebates and incentives to encourage building operators and owners to implement retrocommissioning in their buildings.

Given the numbers of buildings in North America that have not been commissioned, and the ever increasing pressures to reduce energy consumption, it is not difficult to envision that retrocommissioning will become a very popular energy conservation measure in the years to come.

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