Printer Friendly

What we have learned from 20 years of HVAC system commissioning.

INTRODUCTION

Today facility owner groups such as Universities, Healthcare, Laboratories, Mission Critical, Developers and Large Retail are committed to the commissioning of their buildings. Design engineers, as well as contractors, have developed a positive regard for the importance of commissioning, especially in large and complicated projects. Recently, a design engineer related some of his experiences that solidified his belief that commissioning was needed.

1. "Reviewing a balance report with 150+ circuit setters -- only to get on-site and find that none of them were ever installed."

2. "Arriving on-site after an equipment start-up to find that the cooling coil had been "sucked" 3 inches closer to the fan inlet because the contractor didn't open any return air dampers when they started the unit (a lab unit with almost 10" of total static)."

3."I was once asked to price a design on a make-up air handler for an existing lab ... when I arrived on-site I found a modular home filled with lab hoods -- easily breaking about 100 OSHA regulations. Whenever anyone in upstate NY received mail that they thought may contain Anthrax, authorities would send the sample to this "lab" to process the threat -- I didn't stay long."

4. "While performing an energy study on a school in the Bronx the maintenance staff asked that I look at a new building that was nearing construction completion -- air handlers as large as 25,000 CFM were installed with filter and coil pull areas that had no more than 42" of headroom."

5. "While performing the same energy study in the Bronx I found a multitude leaks in the hot water systems throughout campus. The maintenance staff had also found the leaks -- and fashioned funnels under them, which they attached to hoses that went to the nearest drain. The estimated energy loss on these leaks was hundreds of thousands of dollars over the life of the systems."

The late 1960s began an era of the design/build construction delivery of commercial buildings. In many cases, the consulting engineer was left out. The result of which were many buildings that did not perform per the Owner's expectations. Many of these buildings had comfort issues as well as high energy consumption. This, coupled with the energy crisis of the early 1970s, shed light on the fact that buildings could be made more energy efficient without sacrificing comfort and, in many cases, improving it. Building commissioning (Cx) has emerged as the ideal method of verifying and documenting that building systems are installed and operating to provide the performance envisioned by the designer and Owner. Building Cx is relatively new, having its beginning in 1977 when Public Works Canada began to use Cx in its project delivery system. In 1984, the ASHRAE HVAC Commissioning Guideline Committee was formed. In 1988, ASHRAE published the HVAC Commissioning Guideline. Subsequently, the University of Michigan established a facilities evaluation and Cx group in 1988. In the first half of the 1990s, government agencies such as the General Services Administration (GSA), U.S. Corp of Engineers, Environmental Protection Agency (EPA) and Department of Energy (DOE) adopted Cx guidelines; and the first annual National Conference on Building Commissioning (NCBC) was held. In 1996, ASHRAE published Guideline 1-1996: The HVAC Guideline Commissioning Process.

The Building Commissioning Association (BCA) was incorporated in 1998. The same year, the United States Green Building Council (USGBC) LEED criteria included Cx. In 2004, the USGBC introduced LEED-EB that includes a prerequisite for retro-commissioning. The following year, ASHRAE published Guideline 0-2005: The Commissioning Process. In 2006, the ASHRAE Sustainability Roadmap sets an organization-wide agenda to lead the advancement of sustainable building design and operations and announces plans for a certification program for Cx and integrated building design. In 2008, USGBC restructures LEED[R]-EB as LEED[R] for Existing Buildings: Operations & Maintenance, allowing up to 4-points for EBCx and 2-points for ongoing commissioning.

The impetus leading to the evolution of Cx has been Federal Agencies, USGBC and ASHRAE. What started out as commissioning new building HVAC construction has expanded into existing building and ongoing or continuous commissioning. Building envelope commissioning is now common. Many Architectural/Engineering firms who specialize in critical mission facilities and laboratories require commissioning to be a part of the building process.

Commissioning today serves the construction industry to:

1. Ensure that the building will perform per the Owner's expectations.

2. Reduce performance liability for Owners, Designers and Contractors

3. Reduce the number of Change Orders.

4. Be a positive influence to the project schedule.

5. Shorten designers and contractors time at the end of the project.

THE COMMISSIONING PROCESS

My experience over the course of the past 20 years includes over 1,100 projects ranging from $250,000,000 and $100,000. I have first-hand experience to attest that the Cx process has been instrumental in identifying significant issues of performance and high energy consumption. These projects were new construction Cx, existing building Cx, and continuous Cx.

It is important to recall the Owner's issues that were the genesis of Cx. The Cx industry likes to use the phrase "buildings that don't work" when discussing needs. While this is true, it is an oversimplification. As it was, there were buildings that failed to meet the operational expectations of the Owner. Operational failures are more often than not multifaceted issues resulting from disconnect between Owner's expectations, unrealistic Owner's expectations, design issues, installation issues, operating issues and the finished product. Thus, the documented Design Intent and Criteria, or as it is now called, Owner's Project Requirements (OPR) is obviously essential. Owners who have an established building program with a planning, design and construction group are generally not susceptible to unrealistic expectations. The OPR ideally developed by the Owner or Owner/Architect/Engineer should be detailed enough to identify the design solutions; all design parameters; all local codes; all applicable ASHRAE guidelines and standards; and all process codes, guidelines and standards. The OPR should have information that provides expectations for all phases of the project. This document thus becomes the governing document for use throughout the project, including operations. As such, it is the measuring stick for project success. Thus, a well developed and documented OPR defines the project with all subsequent commissioning activities supporting it.

An 'Issues List' is developed by the Commissioning Authority (CxA) with input from the Cx team. All issues are documented; meaning they are dated when entered and dated when resolved with details regarding the action taken and responsible party identified. It is important to understand that an item is only an issue if it is not in accordance with the OPR. With that said, it is rare when all issues are clearly referenced in the OPR. Thus, it becomes the CxA's responsibility to resolve any ambiguity with the Cx team.

In new construction, Cx issues generally fall into these categories:

1. Resulting from lack of or poorly defined OPR.

2. Design issues resulting from documents lacking clear definition of scope; poor system flow and instrumentation diagrams, poorly selected equipment, clear and concise details, clear and thorough specifications; and a concise description of system operating procedures and goals.

3. Construction issues resulting from conflicting details to standard practice, guidelines, and standards; misinterpretation of sequence of operations; misunderstanding of system functionality; mislabeled vendor supplied equipment; shoddy workmanship; and a lack of qualified technical management.

4. Operational issues resulting from system performance issues, lack of 'record documentation', ineffective training and system understanding.

Below is a list of common issues found on projects:

1. Return air fans over pressurizing mixed air chambers. This condition can occur intermittently and is typical of volumetric control return fans.

2. Cross connection of chilled water piping. This occurs at wall penetrations and coil connections. In some cases labeling on the coil is incorrect.

3. Incorrect fill pressure. Incorrect diaphragm pressure in expansion tanks.

4. Instrument calibration not addressed.

5. Air monitoring stations installed in small mechanical rooms resulting in inaccurate readings.

6. AM and PM are switched on HVAC control schedules (or on the computer that the controls reside on) -- meaning that the equipment is scheduled to be occupied just as people are leaving and scheduled to unoccupied settings just before they arrive.

7. Controls contractors not tuning control loops. Recently, a controls contractor didn't tune a humidification loop (therefore ramping up humidity too fast) and repeatedly flooded the discharge air duct detector -- causing repeated nuisance trips and need for the detector to be replaced.

8. Safeties, such as freeze protection, wired to the building automation system (BAS) instead of hard wired.

9. TAB contractors not testing multiple pumps in parallel but rather individually. Parallel pump and system curves are not developed.

10. Wiring issues such as reverse phases. Incorrect size of overload protection.

11. Missing or inadequate record documents.

12. Poorly developed and inadequate O&M manuals from contractors. Lacking specific project related equipment information, and little system information. In most cases system information is left to the controls and TAB contractor.

Examples of issues that are more complex or rare are:

1. A chilled water plant was renovated to a capacity of 6,400 tons. The plant supplied chilled water to 11 buildings of a performing arts center. The new design called for Flow Limiting Devices. These were spool pieces that had a number of orifices that were spring loaded. The orifices would open or close based on a pressure drop across the spool piece. If the pressure drop got too big, spring loaded orifices would start to close. The VFD controlled pumps would, in turn, ramp down until the pressure drop was in range. These were designed and correctly installed on the condenser water return side of five chillers and the supply side 10 cooling towers. Each condenser water pipe from the chillers were between 12" and 16" in diameter. The main condenser water header was 30" in diameter and 100+ feet long. The pumps, chillers and towers were respectively in parallel to each other and connected by headers. The headers were connected in series. During pre-functional testing, the flow was checked with chillers off. With one chiller, pump, tower combination the system worked well. When a second combination of chiller, pump and tower were started the piping began to shake and move violently. After a considerable effort between the CxA, the design engineer and orifice manufacturer, it was determined that the flow limiting devices could be installed either in series or parallel but not both. The five devices were removed from the chillers and the system worked well.

2. A 36,000sf, BSL-3 bioresearch center with vivarium was nearing completion. Ownership decided that it would be prudent to commission the facility given problems with past projects of this nature. The facility was within several months of scheduled opening thus OPR review, design review, submittal review and construction review was moot. A heat recovery system was added by addendum shortly after drawings were released. Initial testing determined that the laboratory air handler would not provide the necessary air changes in the vivarium animal holding room under dirty filter conditions. Other testing found that the laboratory exhaust flow was substantially less than designed. Further testing determined that the air handler pressure was compromised by a system effect issue directly downstream of the unit. It was the result of a structural member that limited the placement of the air handler thus shortening the run out length of the discharge duct. In addition, the fan motor size was maximized. After reviewing all possible solutions including reducing the air exchange amount it was decided to remove the heat recovery coils in the air handler and exhaust duct. The result of which was higher energy usage.

3. A $220,000,000 maximum security correctional center with 2,000 beds and 18 buildings, included a central mechanical plant and an above ground one mile long piping loop. The balancing of the secondary chilled water loop proved to be virtually impossible. In a correction center, the internal load moves throughout the day almost in mass. The simile "like a dog chasing his tail" was appropriate. The result was the secondary flow would at times exceed the primary and flow backwards in the bypass for abnormally longer periods than expected resulting in the inability of the chillers to "see" the load. After a month of adjustments, the loop balance was improved so that the length of time in reverse bypass flow was reduced. As it was, there was overflowing of building flow control valves as building demand increased due to the pressure dependent pumping system. The solution was to add pressure independent flow valves the building take offs of the loop.

ISSUES FOUND IN EXISTING BUILDING COMMISSIONING

Recently Existing Building Cx (EBCx) has become popular and is gaining significant momentum. The popularity is the result of Owners realizing government incentives to engage a commissioning engineer to analyze high energy consumption. The benefit of which is to identify operational issues, indoor air quality issues and comfort concerns. Existing building commissioning is also known as Retro-Commissioning and Recommissioning. The more popular RetroCx is the commissioning of a building that was not originally commissioned. Typically these buildings have issues that have knowingly existed for years or even decades. ReCx pertains to a building that was previously commissioned.

Initially, in areas of the country where high energy cost was not an immediate concern and incentives were non-existent, EBCx primarily addressed nonperformance concerns resulting in resolving comfort issues, improving performance and energy efficiency. Other reasons for employing EBCx include indoor air quality (IAQ) issues.

Examples of issues found in EBCx:

1. During the initial walk-through of a 15 year old, 1,000,000 sf county operated hospital, it was noted that the chillers were operating at a two degree delta T across the chiller bundle. After discussing with the operating personnel, it was noted that the operators were told by their supervisor to maintain the two degree delta. This apparently was passed down from supervisor to supervisor over the years. If the delta T increased they were told to increase pump flow. Notification alarms were set to notify operators during off hours when the delta got greater. The hospital was one of three hospitals operated by the county and operators were routinely rotated. The matter was confirmed by the new manager, as he noted that he has discussed this with operators to increase the delta to 10 degrees. He added that there was some reluctance.

2. A three-story, three year old 500,000 sf office building was to be commissioned as part of the Owner's desire to attain a LEED-EB certification. The building was a design/build project. It utilized a under floor air distribution (UFAD) system with seven large packaged air handling units located on the roof. Chilled water was provided by a central chiller plant, also located on the roof. During the initial walk-through, it was noted that there was a large amount of return air flowing up the open stairwell and entering the return plenum on the third floor. Further investigation revealed that the UFAD system was not performing properly as the temperature profile of the space indicated even temperatures from floor to ceiling. The system was acting as a typical mixing system.

Another issue was the under floor pressure. The building pressure was maintained at 0.08 inches w.g. The under floor pressure was maintained at 0.05 inches w.g. Each was using the outside air as a reference. Thus airflow from the plenum to the space was not uniformed. This was improved by changing the reference for the unfloor pressure control to reference the space pressure. Other recommendations to the under floor duct runs were offered but not implemented due the cost.

Further investigation revealed that the roof mounted unit air return was not connected to the return shaft. As a result the return shaft was in essence a transfer duct however it was not sized to perform as a transfer duct. Thus the return air was returning via the open stairwells. Other significant issues were leaks at the under floor duct penetrations to the plenum. This resulted in supply air bypassed to the return shaft. This was not initially a problem as the return shaft was not a negative pressure shaft.

The return shaft issue was eventually resolved by installing two low rpm propeller fans in the return shaft above the second floor return openings. Once this was in place the UFAD operation worked as required as return air move to the shaft and not up the stairwell. The UFAD temperature profile improved but leakage at the duct penetrations t the under floor plenum got worst. These areas were caulked.

3. A 5 year old elementary school located near the confluence of the Ohio River and Mississippi River found mold growing throughout the building. It is not uncommon for the wet bulb temperature to reach as high as 78 to 80 degrees in the late spring, summer and fall months. Walk throughs and interviews confirmed that mold was found behind hanging pictures and at floor / wall junctures. The staff and students were complaining of sinus issues and several students with immune deficiencies were constantly sick and missing classes. The school district was looking at several lawsuits.

There were approximately 22 classrooms. The classrooms were cooled, ventilated and heated with self-contained wall units. Thirteen ventilators were 3.5 tons and the remaining were 3 tons. Hot water coils in the unit ventilators provided heat. Outside air was introduced through the ventilators. Several constant volume air handling units served the kitchen /dining area, gymnasium, library, and administration offices. The building was a single story, slab on grade, block and steel construction with a combination of carpet and tile flooring. Cellular insulation sheets were installed along the building perimeter under the concrete slab. The insulation extended 6 feet into the building.

A small BAS controlled scheduling and setbacks. The building was setback at night and during unoccupied periods of the summer. Integral thermostats controlled the unit ventilators. During occupied hours the ventilator fans were operated and outside air dampers were opened. The thermostats responded to the cooling and heating needs.

Investigation identified that the 3 ton units were sixed to handle 2 tons of outside air load and 1 ton of the remaining load. It was determined that the 3.5 ton units were oversized. It was also determined that units were not satisfying the code required amount of outside air. There was no dehumidification mode as the hot water coil was in the preheat position. During the spring, late spring, late summer and fall months wet bulb temperatures were typically high. In a typical classroom on a call for cooling the refrigeration cycle would engage, with the outside air damper in the open position. When there was no call for cooling the fan would remain running and outside air damper would remain open for ventilation purposes. This condition didn't appear to be problematic as they (unconditioned air introduction) were thought to be short in duration and as soon as the introduction of warm air raised the space temperature the refrigeration cycle would engage.

Unfortunately, there were two other situations that occurred. The classrooms occupancy would change during the day with periods of non-occupancy as students would be out for recess, library, gym, lunch and labs. The other was that during the spring and fall there were periods of rain when the outside temperatures were in the high 60s and low to mid 70s. The unconditioned air would enter and condense on the tile floor at the wall junctures. Forty eight hours later mold would appear. Mold will grow if there is moisture, organic material and time. When dry the mold would spread.

The solution was to install an outside air make up unit with a total energy recovery wheel and deliver air to the space at room temperature. The unit ventilators were modified to eliminate the outside air intake and change the compressors out to 1 ton. Energy usage was slightly higher.

4. A $125,000,000 Casino/Hotel expansion. Originally the facility was a small casino and a connected 9 story hotel. Two centrifugal chillers located in the facility served the casino's constant volume systems and the hotel fan coil units. The expansion tripled the casino floor and doubled the hotel space. A new standalone chilled water plant was installed on-site with underground hot and chilled water piping serving the building and connecting to the existing piping system. New large air handlers served the new floor with the smaller original air handlers relocated and serving smaller areas.

During the first two years of operations the casino was very negative in the winter resulting in a cold floor and requiring the casino to shut down tables near the main doors. The top three floors of the 9 story new hotel could not be used in the winter. The construction delivery method utilized a Contract Manager, a Construction Manager and multiple trade contractors. The project was phased for the purpose of keeping the casino operating. There were multiple piping, sheet metal and control contractors.

During the initial investigation the major issues became evident. The chilled water underground piping was leaking. It was discovered that the contractor had changed the specified fiberglass pipe to a C900 PVC push joint pipe. The underground hot water pipe was leaking. The contractor had used the specified fiberglass pipe but had not installed the specified anchor system. The chilled water and hot water systems were not operating at the required fill pressure and pump pressure. The chilled water plant had 5chillers and 4 cooling towers.

The cooling towers had no flow control at the towers thus the flow was unbalanced.

The new hotel major issues were insufficient chilled and hot water pressure; air in the piping system; and toilet exhaust without balancing dampers. The toilet exhaust fans were located on the roof. The makeup air unit was located at the first floor and also did not have balancing dampers at the floors. This combination of issues resulted in the top floors very negative with outside air entering the floor from the elevator shafts and stairwells and consequently cold. Thus the floors could not be used.

The casino negative pressure issue was complex but in essence it was a combination of issues that included a lack of sufficient outside air delivered by the air handling units. The new air handling units had a energy recovery wheel and as such had limited ability to introduce outside air. Some of the existing airs handling units were not capable to handle outside air. Other issues were that there were multiple TAB reports completed as phases were completed but there was no TAB performed with all phase completed. Controls and the BAS had the same issue.

The major issue of pipe leakage remains. Completion of EBCx was limited as a result.

Other examples of issues found during EBCx are:

1. While conducting EBCx on a large retail store, a gas pipe that was running along the roof was kicked and it fell apart -- the pipe had never been threaded, it was just laying inside the elbow -- dry-fit. (That particular store had one of the highest gas usages per square foot in NY, and was one of the oldest in upstate NY). The day that this was found the roof was being redone ... with torches.

2. While conducting EBCx on a high-rise building in NYC, 30-year-old induction units with filters that had never been changed were discovered -- some of the nozzles were completely solid with dust and debris, building was typically seeing about 30% of their designed airflow (some spaces were seeing -0- airflow).

3. A university residence hall was in its second year of operation. It had been commissioned. The administration offices were very uncomfortable. The chilled water system was composed of 2 loops one to air handler serving the administration offices and the other serving the 5 story residence hall fan coil units. The distribution pump was controlled by a pressure sensor located on the fifth floor riser. The problem was the air handler which was located about 25 feet from the pump had a higher pressure drop.

4. A historic six-story seminary was renovated into offices. About 350 water source heat pumps were installed. After three years of operation, compressors on the top floor began to fail. It was found that the fill pressure in the water loop was low and incorrect.

5. Attached are photos of other issues found during EBCx.

LESSONS LEARNED

The list below does not include lessons learned that would be best served in passing onto design engineers. That is, answers or considerations for such topics as: What is the most ideal location for a VAV discharge air pressure sensor? Where is two thirds or three fourths of the duct length? Why there? Which method of controlling return air fans works the best?

1. Owner commitment to the commissioning process is essential to a successful project. A commitment of involvement by the Owner's team includes an understanding of the commissioning process and expectations. Occasionally Owners or Owners' representatives take an inactive role in the commissioning process. When the Owner becomes inactive while maintaining a semblance of Owner involvement with an uninformed or misguided Owner's representative the Cx process will be ineffective and the benefits not realized It is a rare project where this management style is successful. Without Owner commitment it is highly possible that there will be no value added from the Cx process and as such is not a wise investment.

If the responsibility is assigned to a member of the project team the success rate improves but is not ideal as there exist a conflict of interest. The Building Commissioning Association (BCA) recognizes this conflict and considers it an essential attribute which is so fundamental to effective building commissioning that all members agree in writing to adhere to them whenever they serve as a project's Commissioning Authority. The attribute as stated is "The CxA is an objective, independent advocate of the Owner. If the CxA's firm has other project responsibilities, or is not under direct contract to the Owner, a conflict of interest exists. Wherever this occurs, the CxA discloses, in writing, the nature of the conflict and the means by which the conflict shall be managed."(1) Conflict of interest exists when the CxA is trying to serve the owner's interest while under contractual obligation responsible for design, construction management, equipment supply, or construction, whose interests may include making a profit, meeting a schedule, or protecting their reputation. A conflict of interest is inherent to such an arrangement. Ethical professionals may be able to manage it to the mutual satisfaction of the concerned parties. The BCA believes that the conflict of interest and the means of managing it should be clearly identified, understood, and documented. The BCA also believes that uncensored communication between the CxA, the owner, and the other members of the commissioning team is an essential component of effective conflict of interest management.

With LEED splitting the Cx process into Fundamental (Pre requisite) and Enhanced a more common method is to split the Cx responsibility into two contracts with Fundamental Cx contracted to the CM and Enhanced Cx to the Owner. Fundamental Cx typically represents 65% to 80% of the total cost of Cx. Thus Fundamental Cx cost is assigned to the project construction cost managed by the CM. The CxA becomes responsible to the CM and organizationally appears the same as the trade contractors. Thus the CxA is selected on lowest bid without a strenuous vetting of qualifications. Today some Federal agencies along with some Universities are employing this methodology. Inherently this jeopardizes the Cx process as a "quality-oriented process" with the unintentional result to water it down and thus become ineffective.

The common denominator of all successful projects over the last 20 years is a high degree of Owner involvement in the Cx process.

2. Equally important to the success of the Cx process is the Owners Project Requirements. It is rare to find failure when a detailed and thorough OPR has been developed and approved. As with all such plans it must be revised and monitored throughout the project. Most importantly it is the measure of project success.

The quality of the document is typically lacking especially in performance detail. Any and all assumptions that the Architect and Engineer make must be identified including Owner and User requirements; design parameters for load calculations; equipment selection criteria; energy efficiency goals; environmental and sustainability goals; indoor air quality requirements; equipment and system operational expectations; building occupant and O&M requirements; and interpretation of applicable standards, guidelines and codes.

The OPR is initially used by the CxA during the Construction Documents review. Any omissions, variances, ambiguities or confusing interpretations of the document is identified and resolved with the Cx team. In effect this is a potential problem exercise with the purpose of strengthening the documents so that they meet the intent OPR.

No better example of the importance of an OPR is exemplified then during the Retro or EBCx 0f a building. Without exception the common denominator of poorly performing buildings is a vague OPR or lack thereof.

3. As mentioned, commissioning is a quality-oriented process, in essence a quality management process. Many commissioning efforts are minimized because there is a lack of technical expertise on of the CxA. Knowledge of the technical aspects of the project is paramount to the commissioning success of the projects.

Some Commissioning firms mistakenly address only the functionality of equipment or systems meaning they checkout the Controls and Sequence of Operations but they do not consider the performance requirements thus they miss the operational requirements of the OPR. In other words how do the systems and subsystems perform as the load moves from one design extreme to the other? Confirming that a damper opens but missing considerations of continuous operations of the damper. Confirming the TAB results of a pump balance but not investigating pump performance during parallel pumping. Single event testing alone is not performance testing. With technical knowledge of system performance single event testing can provide information that assists the CxA.

The industry must do a better job in establishing qualifications of firms not only in the application of the process but in the technical understanding of systems and their applications.

4. To quote one of our Project Engineers "What is remarkable is how minor the items are that I can name on projects I've commissioned -- probably because being on site mitigates so many ridiculous deficiencies from ever happening. The worst stuff that I've ever found was as a design engineer that could have been avoided by performing commissioning":

It has become evident that projects where Owners have employed commissioning services there are the unexpected benefits of reduced issues or deficiencies. In 2001 a 70,000 sf plant science research lab had 858 construction issues. A more recent 40,000 sf bioresearch lab completed in 2010 had 132 construction issues. This is not an anomaly it is consistent with other projects. It is a significant trend among Owners such as Universities who have committed to the Cx process over multiple projects.

The majority of issues eliminated are installation details of accessibility, maintainability, piping details such as reducing pipe sizing from a control valve to a coil connection. Duct details such as duct fabrication details, sealant, insulation and duct support and connections. Temperature control issues related to inadequate point to point documentation and vague temperature control diagrams.

5. The impact of commissioning is intended to positively influence building operations and maintenance. There are several areas where this has been lacking, record 'as built' documentation, O&M training, and Lessons Learned meetings. This is true in spite of close out specifications and various guidelines. Typically, the close-out specifications of a project are not enforced and ignored or lack specific details. ASHRAE Guideline 4-2008 provides O&M close out details that are very seldom specified.

In the case of O&M staff training the commissioning provider is not involved in actual training but is to review lessons, and confirm that it has been provided by the contractors. The O&M manual in nothing more than a collection of vendor supplied equipment O&M manuals. Occasionally the manual will include approved equipment submittals. While equipment training by vendors is typical there is generally no system training with exception to BAS / Temperature controls training by the Temperature Control Contractor. Improvement in this is needed. First the commissioning provider must have a direct involvement including providing system training with assistance from the design engineer. The design engineer must tighten the specifications and provide more detail of contractor expectations.

Lessons Learned meetings are an important way to pass on the valuable information learned as the result of the commissioning process. Unfortunately they are seldom used. Obviously there have been lessons learned by all participants in the course of the commissioning exercise.

THE FUTURE OF HVAC COMMISSIONING

I think that, generally, while we've learned a lot over the last 20 years (as an industry) there is still a long way to go. It seems that systems have become more complex with the changing technology. A visit to the tri-annual AHR Expo trade show in Chicago provides the visitor a glimpse of the enormity of the industry as well as the changing technology. The era of sustainable design including a refocus on energy efficiency, indoor air quality, and smart grid technologies has raised the bar. Furthermore, the construction industry is constantly searching for new or improved project delivery methods to improve productivity and reduce builders' risk.

The more complex systems get -- complicated DDC, etc. -- the more expertise it takes to install the systems and make them work correctly ... which means they are more often misapplied, specified incorrectly, installed poorly, or not maintained properly. Some of the corrections that we make every day seem extremely subtle because we are catching controls issues or tuning buildings rather than just finding gross errors that make buildings unusable -- but their economic impacts are often significant.

When the commissioning process was introduced it was popular to think of it as a "management process", not necessarily performed by engineers. In other words, if the process is followed then personnel with unsophisticated HVAC technical expertise could successfully implement it. Commissioning training was centered on the process. It then followed that when existing building commissioning became popular the focus was also on the process. We have learned that this is

Thus, it has become more and more evident that commitment of continuing training of commissioning personnel is imperative if commissioning is to be of value to the Owner. Commissioning personnel should undergo continuous internal and external training in the commissioning process of both new and existing buildings, mechanical and electrical building system analysis, BAS and temperature control systems, new technologies, sustainable design, ASHRAE Standards, and equipment and systems operations and maintenance.

At the turn of the century commissioning was primarily employed on new construction. Building commissioning was focused on mechanical systems, indoor air quality and ancillary electrical systems such as emergency or stand by power. Ten years later new building construction includes building envelope, and Existing Building Commissioning has move to the forefront with new challenges. On the horizon is Continuous Commissioning and data monitoring which will be driven by the sustainable design movement and smart grid technology. Systems will become more complicated and the technical demands of the commissioning provider will increase.

Initially, the building commissioning process was developed to address 'buildings that didn't work' as the Owner expected. Today we can say the when the Commissioning Process is implemented properly it works -- building commissioning is here to stay!

FOOTNOTES

(1.) BCA Essential Attribute number 2

REFERENCES

ASHRAE Guideline 0 - 2005: The Commissioning Process

ASHRAE Guideline 4 - 2008: Preparation of Operating and Maintenance Documentation for Building Systems

BCA Essential Attributes of Building Commissioning

E. Thomas Lillie, P.E.

ASHRAE Life Member

E. Thomas Lillie, PE is a former Secretary/Treasurer of the Building Commissioning Association and Partner at Horizon Engineering Associates, LLP, St. Louis, MO.
COPYRIGHT 2012 American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2012 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Lillie, E. Thomas
Publication:ASHRAE Transactions
Article Type:Report
Geographic Code:1USA
Date:Jul 1, 2012
Words:6023
Previous Article:Occupant perceptions of an indoor thermal environment in a naturally ventilated building.
Next Article:Modeling and optimization of HVAC systems using artificial intelligence approaches.
Topics:

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters