Background: Many grocery stores are built fairly close to residential areas and have to address noise issues in order to be good neighbors. Some cities have noise ordinances with spe-cific requirements to keep equipment noise below the established threshold during evening/night-time hours. Various design solutions may be employed to accommodate these noise abatement requirements.
Problem: One design resolution to accommodate noise issues is the “stack attack” option shown in the figure. In this design, condenser fan stacks are installed on top of the condensing equipment. Unfortunately, this particular design solution creates service issues and increases costs associated with changing out the condenser fan motors. It is unlikely that these issues will be real-ized until problems arise associated with condenser fan motor failures (e.g., high head pressures).
When that occurs, it is likely that a crane will be required to safely lift the stacks so the condenser fan motors can be replaced and to reset the stacks onto the condenser when the work is completed.
The need for a crane greatly increases the both the costs and time required for what should be rou-tine maintenance. In this particular case study, the cost was increased by $5000 for local crane fees and the replacement took all day.
Lessons Learned: Reviewing the OPR and BoD early in this project should have enabled the identification of alternate design options to meet site noise abatement requirements that do not create costly service situations. This design solution created a very expensive service challenge and an unsafe maintenance process. In addition, once installation is complete, retrofitting this type of situation can be expensive, and the process of reviewing information and evaluating sup-porting systems may impact the operation of the store.
Photograph courtesy of NREL; credit John de la Rosa
Why are Those Stacks on the Condenser Fans?
Refrigeration Commissioning Guide for Commercial and Industrial Systems
Commissioning Process Scope and Budget
Identifying the equipment, components, and systems to be commissioned and assigning a budget to carry out the commissioning tasks is essential.
Depending on the size of the scope and budget, commissioning could be focused on just the control and operation of the equipment in the compressor room, or it could also include condensers, evaporators, piping systems, pumps, peripheral controls, etc.
Technical Procedures
All technical procedures that will be conducted for commissioning, as specified in the Commissioning Plan (see the section “Developing the Com-missioning Plan” in this chapter), must be reviewed, and the CxA must ensure that any information or data necessary for fulfilling a given technical proce-dure is included in the OPR.
Submittal Requirements
Specify how the submittals will be coordinated, reviewed, and approved and who will be responsible for these functions.
Project Documentation Requirements
With input from the owner’s technical representative and the CxA, specify what documentation will be required for effective commissioning, who will be responsible for providing it, and in what format it should be provided. Depend-ing on the nature of the facility and the owner’s preference, the documentation may include only refrigeration-related content or may address all aspects of the facility. Additionally, the owner should specify a method for retaining, storing, and/or displaying these documents in order to preserve them for the life of the system and to allow for updating as changes, additions, and improvements are made to the documents or the facility itself (see Figure 2-2).
Photographs courtesy of NREL; credit John de la Rosa
Figure 2-2 Examples of Displayed Project Documentation
As a best practice, documentation retention should include, at a minimum, the following:
• Owner’s Project Requirements
• Basis of Design documents
• Issues log
• Construction record documents, specifications, approved submittals, and the construction checklist
• Control requirements
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• Start-up records
• Commissioning report
• Systems manual (including operations and maintenance manuals)
• Training materials and optimization guidance
• Ongoing operating data
Ongoing operating data may include the following:
• Refrigerant leak and recharge records
• Oil usage log (additions and removal history)
• Maintenance and emergency repair records
• Equipment logs (periodic manually prepared forms and/or computer printouts)
Training Requirements for Owner’s Personnel
The CxA and all parties who will provide training information should be involved in the development of training requirements and expectations. Input from those who will be responsible for using the training materials is also important.
The expectation for sufficient training should be documented and commu-nicated directly with the expected trainer or included within any applicable RFP. Typically, system manufacturers will offer some sort of training for equipment that is considered unique or a new technology. For example, refrig-erated display cases may require training on how to properly load the cases or operate various features of the cases.
In addition, the training process and timing must be defined. While multi-ple entities may be involved with aspects of training, particularly on a large project or with new technologies, training coordination is necessary to ensure information is fully and effectively made available on a timely basis to the individuals who need it. Chapter 4 discusses how to review the training activ-ity during the Start-Up and First-Year Operation Phase.
Developing training requirements and implementing training for a project involves the following actions:
• Identifying who requires training, when, and how frequently
• Defining who will provide training (e.g., vendors, engineers, training or subject specialists, etc.)
• Establishing a training calendar for the project
• Identifying additional requirements for new technologies or special installation conditions
• Identifying certifications required of operating staff or contractors
• Specifying safety-related requirements per company policy and gov-ernmental agencies (e.g., local codes, Occupational Safety and Health Administration, Environmental Protection Agency, etc.)
• Providing safety training before start-up or change activities
• Providing safety training after completion, with hands-on inter-action
• Providing individual safety qualification on standard operating procedure (SOP), when applicable
• Providing training on remote access, control interface, and other data systems
• Defining the responsibility for maintaining and administering ongo-ing references and trainongo-ing support
Refrigeration Commissioning Guide for Commercial and Industrial Systems
Warranty Requirements
The terms of warranty for all systems and components to be commis-sioned should be collected and included in the OPR for reference so that all warranties may be preserved throughout the project. Chapter 4 discusses how to review warranty requirements during start-up and through the first year of operation.
Benchmarking Requirements
Beyond requiring that benchmarking must be part of the Commissioning Plan, the owner must specify what the benchmark targets will be, when the benchmarking should happen, what the means of measurement are, and what the benchmark deliverable needs to look like. The CxA should help develop these requirements to ensure that the commissioning work performed and the generated deliverable is as meaningful as possible. For example, if weather data and facility conditions are not recorded when the system benchmark is recorded, then the information cannot be used to its full potential. Chapter 4 discusses the documentation of performance benchmarks during first-year operation.
Operation and Maintenance Requirements
Include expectations regarding the yearly maintenance budget and the expected capability of the service contractor. To realistically set these require-ments, collaboration with the service technician may be required.
Load and Sizing Calculations
Designate the responsibility for performing load calculations and define the operational parameters, derating or safety factors, and related system-siz-ing criteria. Adherence to these design parameters and responsibilities should be maintained during the development of the design. Once the system becomes operational, commissioning feedback should be provided regarding the efficacy of the load and sizing calculations and methods.
Environmental Sustainability and Energy-Efficiency Goals
Environmental goals can be expressed in the OPR in many ways, such as dictating what type of refrigerant to use, what the total refrigerant charge should be, how much energy the refrigeration system should use, or even what the system’s total equivalent warming impact (TEWI) or life-cycle climate performance (LCCP) number should be. As previously discussed, depending on the level of internal technical representation available to the owner, the spe-cifics of how to achieve these environmental goals may or may not be included in the OPR. The requirement should still be firm, but it may leave more of the means and methods up to the designer to achieve the end goal.
Any requirements for obtaining building ratings or certifications (e.g, bEQ, LEED®, Green Globes, GreenChill, or ENERGY STAR®) should be specified. The targeted level of awarded certification should also be expressed.
The energy goals of a project are directly related to the environmental goals and, similarly, there are many different ways to address the require-ments. Some of the ways to set the energy requirements are
• requiring equipment to meet a specified payback period,
• referencing an industry energy baseline and requiring that the system either meet this baseline or achieve a certain percentage deviation from it, or
• requiring that the equipment meet a certain preset performance spec-ification that can be verified through kilowatt-hour monitoring.
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System Type The system type is requirement that cannot necessarily be set until after the environmental and energy goals have been identified. Sometimes, the environmental and energy goals will require the use of a type of system that the owner has no experience with. While some owners may give the designer the authority to simply pick a system type and manufacturer that fits their design, many owners have a selection of approved manufacturers and system types that they will require to be used.
Community Requirements
The owner should understand the surrounding community and set requirements to make sure that the team and the installed systems do not neg-atively impact that community. Sometimes community engagement will be necessary to successfully complete a project. For example, projects where vis-ible and/or audvis-ible rooftop equipment will be installed may require approval from surrounding neighbors. With the use of some “natural” refrigerants, the Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA) may come into play and require that certain steps are taken to properly engage the community.
Refrigerant Charge Calculations and Refrigerant Management
The OPR should clearly define the responsibility for calculation of refrig-erant charge(s), confirmation of actual system charge, and identification of any leaks or adjustments needed to accurately define the proper operating sys-tem charge. In order to improve future designs, also define the responsibility for investigating variances from the expected charge and report reasons.
Define the management systems for tracking refrigerant use from start-up through the first year of operation, including continuity between construction and maintenance record keeping.
Adaptability The OPR should specify whether the installed system should be able to adapt and expand to meet the predicted future needs of the facility and, if it should, to what degree it should be able to do so.
Systems Integration Requirements
Include any requirements to integrate the refrigeration system with other systems such as space heating, water heating, lighting, facility control, etc.
Acoustical Requirements
List baseline acoustical requirements and express additional requirements for special situations. Examples of special situations include mechanical room walls that are shared with other tenants or neighbors that are in close proxim-ity to rooftop condensers.
Vibration Requirements
List vibrational requirements, especially when nontypical roof systems or mezzanines are used to support condensers and compressors. Also include seismic requirements for projects that are located in special seismic zones.
Constructability Requirements
In addition to recording any known constructability restrictions specific to the project site, the owner may choose to require that a constructability review be performed by the installing contractor once the CD permit set is issued. The project schedule and construction schedule should be reviewed to make sure that the pieces can come together in the right order. One example of this is ensuring that roof curbing is set before condensers are craned to the roof so that the racks can be ready to run when the evaporators are needed to refrigerate.
Maintainability and Accessibility Requirements
Set requirements for equipment accessibility to allow for proper and effi-cient maintenance. This is a requirement that will demand some architectural coordination to ensure that spaces adequately allow for proper clearances and
Refrigeration Commissioning Guide for Commercial and Industrial Systems
pathways. Proper storage and trash handling should be addressed to reduce garbage and clutter around equipment.
Communication Requirements
Include any remote monitoring requirements for the purposes of mainte-nance, trend logging, or performance comparisons.
Systems Communication and Controller Requirements
Aside from specifying which controls manufacturer should be used, spec-ify what communications should take place between integrated systems.
Beyond this, the expectation should be set for the designer and the controller programmer to closely coordinate throughout the project to ensure that the design intent is executed in the final control of the system (refer to the sidebar