A Strategic Approach to Laboratory Ventilation
Three Steps for Achieving Satisfactory Fume Hood Performance
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Laboratories are specially designed and constructed to attract top scientists and provide safe environments that support testing, research, and development of new products and innovative technologies. Laboratory fume hoods and their associated ventilation systems serve as the primary means of protecting people working in or around labs. However, fume hoods are not independent pieces of equipment. Rather, they are part of a complex fume hood ventilation (FHV) system with numerous interacting components, all of which must function properly to achieve required performance (see Figure 1). This makes FHV systems very costly and extraordinarily challenging to test and maintain. A single fume hood can cost $15,000 to $30,000 to install and an additional $3,000 to $5,000 annually for operation and maintenance. In addition, results of more than forty thousand tests by my company, 3Flow, indicate that one-third of fume hoods may neither function properly nor meet performance requirements described in the recent ANSI/ASSP Z9.5-2022 American national standard for lab ventilation.
Figure 1. Schematic diagram of a laboratory and fume hood ventilation system. Graphic created by Thomas C. Smith.

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Proper performance for the lifecycle of an FHV system can be achieved by employing a proven, risk-based, systematic approach. This three-step process includes a series of tasks for design, installation, and ongoing operation and maintenance. These tasks help reduce problems, promote more dependable operation, and require less effort to diagnose and correct deficiencies that often lead to project delays, continuing safety issues, and occupant dissatisfaction. Furthermore, incorporating the process into a comprehensive lab ventilation management plan (LVMP) improves lab safety, enhances risk management, minimizes energy consumption, and achieves better outcomes for lab facilities. More information about an LVMP can be found in the ANSI Z9.5 standard and the Smart Labs Toolkit from the International Institute for Sustainable Laboratories.
Employing the process during the design of a new FHV system or when upgrading an existing system can yield significant benefits including:  • proper design, installation, operation, and maintenance of fume hoods and lab ventilation  • conformance with national ventilation standards, reduced enterprise risk, and lower potential for liability  • coordination of efforts by relevant stakeholder groups including staff in the facilities, environmental health and safety, and research departments
• safe and controlled environments that support the occupants and promote good science  • minimized energy consumption and support for sustainability and decarbonization efforts 
Although FHV systems may not include all the components depicted in Figure 1, separating the elements as shown helps facilitate selection, design, installation, commissioning, and management of the system. The primary elements include:
Occupants. Their activities, hazards, and performance requirements define the demand for ventilation and serve as a basis for specifying the system’s design.
Fume hoods. Selection, design, operation, and performance of fume hoods and other exposure control devices (ECDs) such as biological safety cabinets, gloveboxes, and local exhaust ventilated devices provide primary protection from exposure to airborne hazards and minimize exhaust airflow requirements.
Lab environment. The lab is designed to meet the functional needs of the occupants and provide secondary protection from exposures. Critical factors include pressurization, space conditioning, air supply distribution, ventilation effectiveness, and control of airborne hazards.
Fume hood and lab airflow controls. These components, which regulate airflow through the lab and ventilated devices, are critical to achieving and maintaining safety performance.
Exhaust and air supply systems. These systems introduce, condition, transport, and exhaust air, providing safe environments while meeting the occupants’ demand for ventilation. 
Exhaust discharge and outside air supply. These elements provide proper indoor air quality and outdoor environmental air quality. 
Building automation and information system. The building automation and information system (BAS) provides access to the network of sensors, actuators, and controls that automate functions of the FHV system. In addition, the BAS facilitates monitoring, analysis, and reporting of operating information that helps verify and maintain proper performance. The BAS and graphical representation of the systems and operation are key elements of the ability to manage modern systems. For more information on BAS, see the article on the previous page.
Strategic Approach to Assured Performance A risk-based, systematic approach considers each of the FHV elements during design, construction, renovation, and ongoing operation. The approach is facilitated by a proven process that includes three major steps divided into a series of coordinated sub-tasks (see Figure 2), which enable safe, energy-efficient, and sustainable performance for the lifecycle of the FHV system.
Figure 2. Steps and tasks for ensuring proper design, installation, operation, and maintenance of fume hood systems. Graphic created by Thomas C. Smith.

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Step 1: Specify and Design the FHV System  The outcome of step 1 is a clear and comprehensive scope of work with supporting design documents for constructing or upgrading an FHV system and enabling compliance with all relevant codes, standards, and system specifications. The design documents should include information about occupants; risk assessment data; system drawings; engineering specifications; equipment schedules; the testing, adjusting, and balancing (TAB) plan; and the commissioning (Cx) plan. The TAB and Cx plans provide specific information about how the airflow control valves will be tested and adjusted to the design flow specifications. The TAB plan describes the process and the data to be collected and reported to demonstrate proper air balance. The Cx plan describes how the FHV system is to be tested to verify proper operation and tune the system to provide optimal performance of the FHV system over the range of possible operating modes from low flow to high flow. In addition, the TAB and Cx plans specify the data that must be provided by the TAB and Cx contractors to support the FHV system.
The following tasks are associated with step 1:  • Task 1: assess risk and occupants’ demand for ventilation to determine appropriate types of fume hoods, ECDs, and other appropriate safety measures
• Task 2: establish design standards, operating specifications, and safety performance criteria that include the appropriate physical attributes and operating parameters to meet occupant needs and their demand for ventilation
• Task 3: review and approve “as manufactured” tests that demonstrate performance of the fume hoods, ECDs, airflow controls, and monitors to confirm satisfactory performance and establish operating specifications and failure modes
• Task 4: review and approve FHV system design, TAB and Cx documents, plans, and specifications prior to purchase and installation of the FHV system
Step 2: Install and Commission the FHV System  Following installation and adjustment of flow to the design specifications, all elements of the system should be inspected and tested to verify that operation and performance of the systems meet the design intent over the range of possible operating modes—for example, with the sashes closed and open, with the building occupied and unoccupied, and during flow and temperature setback modes as well as any other modes that vary operation. The outcome of step 2 is an FHV system that satisfies occupants’ demand for ventilation, meets design specifications, performs properly, and complies with all relevant codes and standards. The operation of the FHV system is clearly documented, including airflow and corresponding energy consumption across the entire range of potential operating modes. All documentation assembled throughout steps 1 and 2, including “as built” construction drawings and one-line diagrams that represent the final configuration of the FHV system, equipment schedules, the TAB and Cx reports, and a building airflow management plan, form the basis of an FHV system management plan.
The following tasks are associated with step 2:  • Task 1: inspect FHV system components during installation and startup
• Task 2: review ventilation TAB activities to verify proper test methods and flow calibration 
• Task 3: review commissioning efforts to tune ventilation system operation and the tests employed to verify proper operation of the exhaust and air supply systems and components 
• Task 4: review lab environment commissioning and functional tests to verify the airflow controls are meeting operational specifications across the range of operating modes 
• Task 5: observe precursive fume hood commissioning tests to verify that the fume hoods and labs are operating in conformance with design specifications prior to undertaking fume hood tests that verify and certify performance meets relevant codes, industry standards, and design specifications
• Task 6: observe and approve FHV system commissioning and certification tests to verify and benchmark performance prior to occupant use 
• Task 7: one of the most important deliverables for step 2 is provision of an FHV system management plan that documents operation, benchmarks performance, and provides procedures for monitoring, testing, and maintaining performance
Step 3: Test and Maintain FHV System Performance  To ensure continued performance, the FHV system must be monitored and maintained using a combination of physical, administrative, and management techniques described in the FHV system management plan developed in step 2, task 7. Available through the plan are the “as built” mechanical drawings, FHV system one-line diagrams, system component inventory list, airflow spreadsheet, TAB report, system Cx report, fume hood certification results, and key system metrics. The plan also includes procedures for testing and maintenance, use of the BAS to monitor operation, and a management of change process for identifying and reacting to changes in the occupants’ demand for ventilation or potential degradation in system performance. Incorporated into the FHV system management plan, the following tasks are conducted at least annually or as determined by monitoring, testing, or maintenance:
• Task 1: conduct exhaust and air supply system tests and maintenance to confirm that the exhaust fans and air handling units are operating properly and providing the required airflow through the building across the range of operating modes 
• Task 2: conduct lab environment and airflow control tests and maintenance to confirm the FHV system meets the required operating specifications over the range of operating modes
• Task 3: conduct fume hood and ECD tests and maintenance to confirm the FHV system meets operating specifications and safety performance criteria
• Task 4: identify and manage change by modifying the system’s configuration or operation to meet changes in the occupants’ demand for ventilation or accommodate changes in performance
BETTER OUTCOMES FHV systems are complex, costly, and particularly challenging to design, install, operate, and maintain. They are also the primary means of protecting people working with airborne hazards in labs and critical workspaces. In addition, they are the largest consumer of energy and contributor to greenhouse gas emissions in laboratory buildings. Unfortunately, the results of thousands of tests indicate performance of as many as one-third of fume hood systems is suboptimal, resulting in potential safety issues and excess energy consumption.
Where it is determined through a risk assessment that an FHV system is desired to help protect people from exposure to airborne chemical hazards, the selection, design, installation, and use of the system is facilitated through implementation of the three-step process described in this article. Incorporating the process into a lab ventilation management plan further aligns the efforts of all stakeholders involved in design, construction, and operation of the FHV system and helps ensure satisfactory performance throughout its lifecycle. Strategic deployment of the process enables better outcomes for the occupants, system stakeholders, and the laboratory facility in terms of safety, occupant satisfaction, energy efficiency, and environmental sustainability.
THOMAS C. SMITH is president of 3Flow in Cary, North Carolina, and a member of the ASHRAE 110, ASHRAE TC9.10, ASHRAE SPC 129, ASTMZ9, and ASTM Z9.5 committees.
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