Examples
Worked examples
- Is an instance
A university facilities and EHS office runs an annual "Shut the Sash" competition, walking labs monthly to record which fume hood sashes are closed versus left open outside active use and posting closure-rate rankings by department as part of campus energy/sustainability reporting.
- Is an instance
A lab manager writes "close the sash to its minimum position before leaving the bench" into the lab's SOPs and onboarding, tying it to the lab's participation in a green-lab certification program such as My Green Lab or LEAF (Laboratory Efficiency Assessment Framework).
Counter-examples
Looks similar, but isn't
- Not an instance
Keeping the sash at the posted working height (commonly around 18 inches for vertical sashes) while actively using the hood — this is standard safe operating practice tied to the hood's containment certification, not the "shut the sash" behavior, which applies specifically when the hood is idle.
- Not an instance
Closing the sash on a constant-air-volume (CAV) fume hood — CAV systems exhaust a fixed air volume regardless of sash position, so closing it is still good safety practice but does not reduce building exhaust energy draw the way it does on a VAV hood; "shut the sash" as an energy-conservation practice is calibrated to VAV-equipped buildings.
Editorial commentary
“Shut the sash” is both an instruction and the informal name for an institutional energy-conservation practice built around a single behavior: lowering a fume hood’s sash to its closed or minimum-opening position whenever the hood is not in active use. The phrase covers two related things — the physical habit itself, and the organized behavior-change campaigns (decals, competitions, dashboards, EHS newsletters) that laboratories and university facilities/sustainability offices run to get researchers to do it consistently.
Why it matters
Most fume hoods installed in newer laboratory buildings are variable-air-volume (VAV) systems: the building’s ventilation controls throttle the volume of conditioned lab air pulled through the hood in response to sash position. An open sash means a larger face opening, which the VAV controller compensates for by exhausting — and therefore replacing with newly conditioned makeup air — a proportionally larger volume of air. A sash left open on an idle hood, overnight or over a weekend, keeps that higher exhaust rate running the whole time for no safety benefit, since nothing is being manipulated inside the hood. Because laboratory air is typically single-pass (not recirculated, for containment reasons) and often heated, cooled, and humidity-controlled to a tighter tolerance than office space, the energy cost of over-ventilating an idle hood compounds significantly across a building with dozens or hundreds of hoods running continuously.
“Shut the sash” campaigns target exactly that gap: they don’t ask researchers to change how they work at the hood, only to close it when they step away. The most widely cited example is the program that originated at the Massachusetts Institute of Technology, which paired the behavioral ask with visible reminders and lab-by-lab feedback; the same basic model — decals at the sash line, periodic walk-throughs scoring which hoods were left open, and public reporting of results by building or department — has since been adopted, adapted, and renamed by EHS and sustainability offices at many other research universities.
How it differs from routine safe sash operation
“Shut the sash” is a distinct behavior from keeping the sash at its certified working height while actively working, which is a core chemical-hygiene and containment practice covered by a hood’s certification and posted operating instructions (see fume hood sash height and safe operating practices). The two behaviors are complementary but answer different questions:
- Working height — how far open should the sash be while I’m actively manipulating something inside the hood? (Answered by the hood’s posted certification, typically a fixed vertical opening the mechanical sash stop enforces.)
- Shut the sash — what should the sash be doing when nobody is working at the hood at all? (Answered by the energy-conservation practice this term describes: closed, or at the hood’s designed minimum opening.)
A lab can be fully compliant on the first point — every researcher uses the correct working height every time — while still leaving substantial energy on the table on the second, if sashes sit open on unattended hoods between uses. Campaigns built around this phrase exist specifically to close that gap without touching containment practice.
Worked examples
- A university facilities and EHS office jointly runs an annual “Shut the Sash” competition: staff walk labs monthly, record which fume hood sashes are closed versus left open outside of active use, and post rankings by department. Aggregate sash-closure rates and the corresponding reduction in exhaust airflow are reported to lab leadership as part of the campus’s broader energy or sustainability reporting.
- A lab manager writes “close the sash to its minimum position before leaving the bench” into the lab’s standard operating procedures, alongside routine chemical-hygiene housekeeping items, and references it in onboarding for new lab members as one of the lab’s requirements for participation in a green-lab or sustainability certification program such as My Green Lab or LEAF (Laboratory Efficiency Assessment Framework).
Counter-examples
- Keeping the sash at the posted working height while actively using the hood. This is standard safe operating practice, not the “shut the sash” behavior — the certified working height (commonly around 18 inches for vertical sashes) is what containment testing was performed against, and it should not be lowered further while someone is actively working inside the hood. “Shut the sash” specifically applies to hoods that are idle.
- A constant-air-volume (CAV) fume hood. CAV systems exhaust a fixed volume of air regardless of sash position, so closing the sash on an idle CAV hood is still good safety practice but does not reduce the building’s exhaust energy draw the way it does on a VAV hood. “Shut the sash” campaigns, as an energy-conservation practice, are calibrated to VAV-equipped buildings; a building running only CAV hoods needs a different set of energy interventions.
Related reading
Machine-readable encodings
Use in your systems
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