This document discusses the history and current state of chemical fume hood design, use, and energy efficiency in university laboratories. It notes that while fume hoods were originally intended to control fires, they are now widely used to protect health without clear definitions of risk. The document outlines challenges around balancing safety, costs, and energy efficiency and suggests taking a holistic risk assessment and management approach. It also provides several examples of strategies universities are using to reduce fume hood energy usage without compromising safety.

1. Sponsored by:
American Chemical Society, Campus Consortium for
Division of Chemical Health & Safety Environmental Excellence
http://www.dchas.org http://www.c2e2.org

2. Ralph Stuart, CIH
Environmental Safety Manager
University of Vermont

3. • Design History
• Open windows
• Laboratory furniture
• Pre-installed building equipment
• Integrated laboratory ventilation systems

4. • In the 1980’s, the rule of thumb was that
face velocities between 100 and 150 fpm
were the best indication of “safety”
• In the 1990’s, studies indicated that
measuring face velocity was not enough, so
tests using tracer gas were developed
(ASHRAE 110 testing)

5. • 1980’s: “It’s the labs’ problem”
• 1990’s: OSHA Lab Standard led to
Environmental Safety certification of face
velocity
• Around this time, maintenance workers
began to deal with hoods more systematically
• Upward exhaust
• Managing combined exhausts
• In the 2000’s, ASHRAE tracer gas testing of
containment “as installed” has become
common

6. • From an energy point of view, hoods are the
equivalent of a open window year round.
• Energy considerations focus on the volume of air moved
(air changes per hour) rather than its speed.
• Traditionally, facility managers have erred on the safety
side by over-ventilating laboratories
• As the number of hoods has proliferated and fuel
costs have risen, energy concerns have made
assessing “hood performance” more complicated
• Many ways of reducing the air volume exhausted have
been proposed.
• HVAC engineers now speak of “high performance” hoods
with regard to energy use, but (hopefully) without a
change in safety performance

7. • Laboratory buildings represent 15-20% of
campus floor space, but consume around 40%
of the campus’ energy
• Studies have found that only about 20% of the
installed hoods are used and someone is at
used hoods only 20% of that time.
• These observations lead to questions:
• Are chemical hoods and laboratory ventilation are the
best approach to laboratory safety?
• Do our laboratories really need to be open 24-7
with full HVAC services?
• Can we make assumptions about chemical risks
in the lab?

8. • Fume hoods were developed to control flammable
chemicals to control fires
• The chief reason for the popularity of fume hoods is that it is a
very adaptable design
• The design has been re-purposed to serve as containment
devices to protect human health from unclear potential risks
using the ALARA approach
• However, user behavior can trump design:
• To achieve ALARA, it’s important that lab workers follow good
hood work practices
• Proper use of a chemical hood requires a risk
assessment of the chemicals used so that the
protection strategy is clear.

9. • ANSI Standard Z9.5-2003
• Outlines a Laboratory Ventilation Management Program
with appointment of “responsible person” to oversee
laboratory ventilation systems.
• The general approach of the standard follows the
“management system” approach.
• This standard is referenced by many designers as well
as in the Labs-21 proposed LEED criteria

10. • Process Analysis
• Plan: Design
• Do: Use
• Check: Cost of operation
• Act: System maintenance
• Stakeholders
• Laboratory Designers
• Laboratory Workers
• Upper administration and
sustainability office
• Facility Operations and
Maintenance

11. • Laboratory Designers:
What hoods should we buy?
• Laboratory Workers:
When should I use hoods?
• Upper Management and Sustainability Office:
Do hoods have to cost so much?
• Campus Facility Managers:
How much money do I need to operate and
maintain hoods?

12. • External standards
• Fire Protection: NFPA 45
• Containment: ASHRAE 110
• Energy Use: LEED and Labs-21
• Possible design criteria
• Hoods must pass ASHRAE As Installed (0.1 ppm
leakage at 4 liters/minute); passing face velocity must
be established at installation
• Energy conservation in design: basis of design
documentmust describe design features (occupancy
sensors, sash sensors etc.) and be translated to users

13. • 40% workforce turnover every 2 years
• User signals and training:
1. Tell tales to determine if the hood is on
2. Warning signs in first 6 inches of hood
3. Safe Operating Height sticker
4. Close the sash reminder poster

14. • GHG impact: one chemical hood is the energy
equivalent of about 3 houses
• Each hood represents about $5000 to
$10,000/year in energy costs
• Laboratory buildings represent at least 35% of a
research campus’s energy use

15. • Hood maintenance needs:
• Face velocity check
• Calibration of alarms and controls
• Preventive maintenance of fans and hood
components
• Repairs
• System adjustments during renovations
• Re-commissioning and retro-commissioning
for proper hood performance, with regard to
both safety and energy

17. Robin M. Izzo
Associate Director
Princeton University
Environmental Health and Safety

18. • Effective at lower face
velocity
• Pass ASHRAE, EU tests
• Problems – design and
use
• Higher first costs
• Larger footprint

19. • Close sash when no one is
using the hood
• Princeton Step Pad Study:
time in front of hood = 5%
• Technology has improved
• Issues:
• Auto close vs. open
• Timing
• Proximity vs. motion

21. • Variable Air Volume is almost the standard
• Set back when unoccupied
• Timers
• Light switch
• Sash position
• Occupancy Sensors
• Higher first costs, quick payback
• Higher maintenance than Continuous air

23. • Especially useful with VAV systems
• Maximum number of hoods in use with sash
open at the same time
• Significant first cost savings
• Be realistic!!
• Always design n+1

24. • Teaching lab solution
• Three settings:
• On
• Off
• Set-up
• Lab instructor controls with key
• Princeton: per week
• on 15 hours, off 153 hours

25. • Not really fume hoods
• Limitations
• Filters
• Flow
• Code requirements
• Maintenance
• Limited application
• Gaining popularity
• Emerging technologies

26. • Old School: minimum 10-12 ACH (air
changes per hour) occupied
• New School: varies
• Computational Flow Dynamics Modeling
• Active Chemical Monitoring
• Some have gone to 4-8 ACH occupied or
lower based on these

27. • Know the applications
• Know the building
• Maintenance is key
• Still need a minimum airflow in the lab
• Limiting factor - USERS

28. • Very few regulations specifically about fume
hoods
• Many guidance documents
• International Mechanical Code 510
• Adopted by many municipalities
• 2006 version includes exemptions for labs
• Your mileage may vary

29. • Defines Hazardous Exhaust
• Precludes manifolding
• Requires sprinklering within the duct
• Requires detection within the duct
• MOST LAB APPLICATIONS fit under the
laboratory exemption
• Documentation is the key

30. • Work with your design team
• Talk to the users
• Understand the applications
• Look beyond those applications
• Try the options on for size
• Installation, visits, meetings
• There is no panacea – just because it works
for Princeton…

32. Sponsored by:
American Chemical Society, Campus Consortium for
Division of Chemical Health & Safety Environmental Excellence
http://www.dchas.org http://www.c2e2.org