FEDERAL ENERGY MANAGEMENT PROGRAM

Fume Hood Sash
Stickers Increases
Laboratory Safety
and Efficiency at
Minimal Cost:

Case Study at a GlanceTechnology used at UC Davis andSanta Barbara
Installed colorful sash position
stickers on fume hoods that:

Success at two Universityof California Campuses

1. 	Reminds workers to close the sash
after use.

Fume hoods represent the first line ofworker safety measures in a researchlaboratory. Providing supply and exhaust
air to fume hoods is highly energy intensive. A typical six-foot hood exhausting
air at 100 linear feet per minute (LFM)and open 18 inches exhausts almost
1.5 million cubic feet of conditioned air
every day. As opportunities for energy
and resource conservation are found inlaboratories, the clarion call of “shut thesash” goes forth, yet still many researchers don’t hear the call or forget themessage. It is not unusual to find unattended hoods opened beyond 18 inches
and remain that way for weeks.

3. Increases sash closure persistence.

Fume Hood Sash Sticker
Technology Overview

confused by labels placed at 18 inches
that say “Place Sash here for Maximum
Safety.” The authors of these labels haveconfused “maximum” and “minimum”,
not realizing that a hood is least safe
when fully open.

In response to this obvious waste ofenergy, elaborate campaigns achieve
essentially 100% compliance to close
fume hood sashes during initial publicity
efforts and from a period of incentives.
However, following this initial state ofheightened worker awareness, somedecay in their diligence follows withina month or two.
It is not surprising that researchers do nothabitually close sashes. They are very
focused on their research, not laboratorybuilding performance and energy conservation. Even when instructions on sash
use are given, they are often combinedwith many safety lessons. There is amixed message of “the hood is certified
safe when open” and “close the sashfor energy savings” that can be further

2. Maximizes VAV system efficiency
and worker safety.
4. Builds professional work habits.

Savings Achieved at UC Davis
Project effort with student assistance• Approximately 600 stickers
were installed.

Per hood installation cost = $5
Simple Payback at UC Davis• Estimated, at $7/CFM/yr = ~15 hours!

Return on Investment (ROI) = ~599!

A Basic Solution
To address the confusion at theUniversity of California, a lab manager
and a hood safety specialist designed abold vinyl sticker to attach on the exterior
sidewall of a fume hood (Figure 1). Thesticker cleverly uses the ubiquitous traffic
light color scheme, with a red zone above
18 inches, and a large arrow pointing
down with the words, “More Safe, Less
Energy” changing from yellow at themidpoint to green at the bottom when thesash is closed completely. Interestingly,a nearly identical sticker was designed
without words and installed at the Danish

Technical University in Copenhagen,where utility companies give rebates for
its placement. Since 2009, the design
has been shared with many campuses
from Denmark to Singapore. As a publicservice, UC Davis prints and can provide
this copyrighted sticker. From this casestudy, it appears the sticker promotes safeand efficient operation of fume hoods.

Implementation
In summer 2009, about 600 stickers weredeployed in ten buildings at UC Davisand about 200 stickers in seven buildings
at UC Santa Barbara. UC Davis hoods
were chosen with safety and energy
priorities. To improve safety awareness,
two UC Davis chemistry buildings wererecipients of the stickers even though
they predominantly had constant air volume (CAV) fume hood systems and, thus,
would see negligible energy reductions
compared to a variable air volume (VAV)
fume hood system. For safety and energy
savings, all buildings with VAV systems
were “stickered.” At UC Santa Barbara,
only VAV lab buildings were stickered.
Survey efforts
At UC Davis, visual surveys of sash-position status were conducted: before sticker
deployment; about 2 months after stickerinstallations; and again in spring, 2011,
to assess persistence. The survey method
estimated sash status by benchmarks inapproximate quartiles to streamline thesurvey effort. This also helped capture
information on VAV-system response.
These benchmarks were assigned values
as follows:• 24 inches: anywhere above the 18 inch

sash stop• 18 inches: at the sash stop
• 13.5 inches: between 9 and 18 inches• 4.5 inches: between 0 an 9 inches• 0 inches: less than 2 inches.

These benchmarks were incorporated
into energy savings calculations. Sashpositions were averaged by floors at eachsample time.

2FEDERAL ENERGY MANAGEMENT PROGRAMAt UC Santa Barbara, surveys wereconducted by collecting real-time sash
position data provided by the campus’
building monitoring system (BMS). Data
were collected for 10-day periods prior tosticker installation for select fume hoods,and one, two, and three months following
sticker installation. The average sash
height for each hood was calculated foreach 10-day period.

Technology Safety Benefits
A fume hood’s primary purpose is tocontain hazards including fumes anderuptive events. It is clear that a closedsash hood is the safest hood, and for thesereasons alone sash closure needs to be aprofessional standard in all laboratories.
The personnel safety savings from one
contained event are precious, and will not
be assigned a monetary value here. Thesash stickers reinforce this training andremind workers of both the safety and theenergy implications of inattentive sash
management procedures.

Implementation
Assessment at UC Davisand UC Santa Barbara
Assessment of implementing the sticker
installation project was provided througha number of surveys. At UC Davis, thetime of the survey of low-use hoods was
not controlled because occupancy was
low regardless of time. For high-use
hoods, surveys were conducted during
the middle of the research day, and before
9 am when occupancy was very light.
At UC Santa Barbara, surveys wereprovided continuously by the BMS.

Energy saving persistence
Surveys at UC Davis of ten researchlaboratories, with a low-density numberof fume hoods, showed 90-100% compliance 22 months after installation withno additional reinforcement of closure.
Figure 2 shows typical response before,
2 months after, and 22 months afterinstallation. Averages less than 2.4 inches
open indicate essentially 100% compliance. Similarly, sticker installation had astrong impact on sash closure persistence
in a building at UC Davis with a highfume hood density, especially overnight.

At UC Santa Barbara, compliance results
were similar. In Figure 3, pre-installation
average night-time sash positions were15 inches in the ESB lab and 7.35 inches
in the CNSI lab. Following the sticker
installation, 23 months later, thesenight-time sash positions decreased to9.38 inches and 4.8 inches, respectively.
More importantly, hourly sash position
data for individual hoods trended in thebuilding control system highlight thewide differences between compliant andnon-compliant laboratories, and provide
impetus for strategically targeted outreach efforts. The data also provides
highly quantitative visual evidence ofthe problem, which is one of the best
ways to motivate behavior change
among scientists.

Estimating savings performance
Energy savings estimates based solely
on sash position are not straightforward.
To understand savings performance,
consider that a lab may have either ahigh-density fume hood count or a lowdensity fume hood count, based on thenumber of hoods per unit of floor area.
In a high-density situation, the volumeof lab exhaust air is dominated by fume
hood requirements. In a low-density
situation, the volume of lab exhaust air isdetermined by a required ventilation ratethat is provided in combination with ageneral exhaust. It is clear that sash position in a fume-hood-dominated lab will
significantly impact energy use and muchless in a low-density fume hood lab.
Fume Hood Density
A simple rule-of-thumb indicates whena lab may be fume-hood-dominated.
Many laboratory designs use ventilation
guidelines that set minimum airflow
at 6 air changes per hour (ACH) witha 10 foot high ceiling, or 1 CFM/SF.
Therefore, in a medium size lab of
1,000 SF, the total exhaust would be
1,000 CFM. Interestingly, this is nearly
equivalent to the exhaust flow rate of one
CAV six-foot hood, calculated as follows:with sash fully raised, the open area isapproximately 6 feet x 2 feet face area, or12 SF; fume hood face velocity rate isFigure 1: Fumes Hood Sticker.

3

FEDERAL ENERGY MANAGEMENT PROGRAM

Figure 2: Sash Closing Persistence at UC Davis, Genome and Biomedical Facility.

Technology Results
Data collected at UC Santa Barbara by
their BMS provides a view into howusers interface with their fume hoods andmanage sash positions. Figure 4 presents
hourly BMS trending of sash positions
over two 7-day periods; before and after
sticker installation. Non-complianceis indicated by high horizontal lines atnight in the uppermost plots. Targetedoutreach to improve sash management
was implied. Beneficially, BMS trending
supports follow-up outreach to be focusedin problem labs.
Improvement in night-time sash closureand frequent daytime openings, as wellas an apparent increase in day-time use,
is fairly are evident. The upper plot of
averaged values (red lines) indicates thatwithout sash stickers (uppermost plot
for each building), the opening remainedlarge without much daily variation.
Conversely, with sash stickers, theaveraged plot (blue lines, bottom plots)
shows a generally smaller opening thatchanged greatly between occupied andunoccupied periods.

Lessons Learned
Figure 3: Sash Closing Persistence at UC Santa Barbara.

typically set at 100 LFM. Therefore, theopen face area times flow rate = 12 x 100= ~ 1,200 CFM. Thus, in this generalized
scenario, a lab with only one six-footwide hood in a 1,000 SF lab the airflow
volume will not be appreciably affectedby sash position.

hood saves a guaranteed, fixed amount ofmoney. However, at UC Santa Barbara
in a lab building with a high fume-hooddensity, an average reduction of 185
CFM was verified that equates to $1,300savings annually per fume hood, using theairflow costs presented in the next section.

VAV Energy Saving Benefits
A laboratory fume hood system is usually
CAV or VAV. Airflow volume in CAV
laboratory buildings will not change
appreciably relative to sash position, andthus have negligible energy savings fromsash closure. Whereas, in a VAV laboratory building, airflow volume should varysignificantly depending on the number offume hood sashes that are open. Also ina VAV lab space, if fume hood exhaustis less than laboratory air change rate,then fully closing sash(es) will havenegligible impact on energy use, suchas in the low-density spaces describedabove. Therefore, not every closed fume

Airflow Cost
Savings will result by reducing fume
hood exhaust that is greater than neededto achieve a required ventilation rate
in a lab room. A common metric (in2011) for the value of conditioned air is$7 per CFM per year assuming 100%
once-through outside air. Note that thisvalue would increase with very hot, coldor humid climates. Thus annually, using
a 6-foot VAV fume hood at 10% fullopen for experiment set up, 25% at 18
inch working opening and keeping thesash closed 65% of the time would save
approximately $6,000 every year compared to constant fully open hood.

Good worker safety practices, including
carefully monitoring sash position, will
become increasingly important as laboratory ventilation designs are reduced tominimize operating costs. Some laboratories are already designed or retrofittedwith setback ventilation or demand
control ventilation making the positionof fume hood sashes a critical element ofboth safety and efficient operation. Datafrom this case study shows that design
diversity factors (number of closedhoods) may be increased substantially,
reducing laboratory building cost.

Reinforcement Needed
The case study indicated that persistence
in closing the sash was not absoluteand may be influenced by fume hooddensity and type of scientific research.
Some decrease in sash closure rates wasobserved over time at both UC Davisand UC Santa Barbara, highlighting
the need for some level of continuous
reinforcement of the sticker message. In
one facility, there was low compliance4FEDERAL ENERGY MANAGEMENT PROGRAMAcknowledgements
Primary Case Study Author:
Geoffrey C. Bell, P.E.
Lawrence Berkeley National Laboratory
One Cyclotron Road
M.S. 90-3111
Berkeley, CA 94720
Voice: (510) 4864626
e-mail: gcbell@lbl.gov
Primary Research Contributors:
Allen Doyle, Sustainability Manager
University of California, Davis
436 Mrak Hall Dr.
Davis, CA 95616-5203
Voice: (530) 752-2075
e-mail: apdoyle@ucdavis.edu
Figure 4: Average sash position before and after sticker installation at two UCSB buildings.

in high-density, high-use hoods regardless of time of day, indicating thatadditional reinforcement of sash closure
behavior is needed. An extra measureof reinforcement is especially importantin laboratories that are fume-hooddominated. Therefore, issues that centeron fume hood dominance in a lab willneed particular attention during worker
training exercises relating the importanceto safety and energy savings, with thissticker reinforcing those lessons.

CAV versus VAVThe complexity of CAV versus VAVfume hood system designs need not confuse a hood user during training. From
the worker’s perspective, all hoods look
the same and need to be treated with thesame habit: Close the hood sash unless
your arms are working inside the hood.
The importance of this simple message
cannot be stressed enough.
BMS Enhances Compliance
Buildings equipped with BMSs can havealarm tools designed to alert maintenancestaff of problems within the buildings.

These tools can also be used with minimal
effort to provide real-time feedback tofume hood users. Staff can periodicallyreview sash behavior and address problem
labs individually, or the system can be
set up to send automatic e-mail alerts tolaboratory managers or occupants whensashes have been left open overnight. In
either case, having real data to present tousers illustrating their behavior can beeye-opening; many users close their sashes
much less reliably than they think they do.

Next Steps
The energy savings realized from thisproject exceeded all expectations. The
trivial cost to install the sash stickers
is dwarfed by the operating cost reductions due to the decrease in airflow in
VAV fume hood systems. The safety
benefits gained by good sash operatingprocedures are realized in both CAV andVAV laboratories. Therefore, since thebenefits of installing the sash stickers are
so dramatic, we believe that this type ofsticker should be installed on every fume
hood in the U.S.

Amorette Getty, Ph.D.,
Postdoctoral Fellow,Laboratory Efficiency
Institute for Energy Efficiency
University of California,
Santa Barbara, CA
Voice: (805) 323-6769
e-mail: amorette@iee.ucsb.edu
Student Volunteers included the UC
Davis CalPIRG team and Physics major
Ziming LiUCSB Laboratory Research andTechnical Staff (LabRATS) interns
assisted in sticker installation.
Jesse Bickley at UCSB EnvironmentalHealth and Safety collaborated in theinitial sticker design

For more information on FEMP:Will Lintner, P.E.
Federal Energy Management Program
U.S. Department of Energy
1000 Independence Ave., S.W.
Washington, D.C. 20585-0121
Voice: (202) 586-3120
william.lintner@ee.doe.gov

For more information and resources, visit the FEMP website atwww.femp.energy.gov.
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CSO 23029
March 2012