f a c t
s h e e t
Energy Efficient Fume Hood Management
Fume hoods are big contributors to two things in laboratories: safety and energy
consumption. Engineered to prevent exposure to hazardous chemicals and gasses, fume
hoods are among the most commonly used pieces of engineered safety equipment for
conducting chemical research. However, with providing this essential protection to
researchers comes a large energy cost due to the air exchange used by the fume hood.
Fume hoods function as an engineered safety mechanism by exhausting air through the
hood face to the outside of the building, therefore removing any harmful fumes away
from the researcher. It is in this design that the energy consumption increases, as energy is
used not only to run the equipment, but to also move the air (heated and cooled) from the
lab through the hood. In other words, each chemical fume hood used in MIT’s
laboratories can use as much energy as 2-3 single family homes. With over 1,100 fume
hoods on campus there is a lot of opportunity for energy savings in each lab.
Key Facts
Fume Hood Issue Resolution:

There are approximately 1100 fume hoods between MIT and Lincoln Labs. Of
the 1100, 600 are variable air volume (VAV) and 500 are constant air volume
(CAV).

CAV fume hoods move the same amount of air regardless of the sash position
and operate at maximum air exchange at all times.

VAV hoods use sensors to calculate the pressure differential necessary to
maintain a constant face velocity. Air volume may be adjusted using a closedloop or open-loop control. Closed-loop control uses a small air speed sensor
embedded in the hood to measure the face velocity and adjust dampers to
change the air volume accordingly. Open-loop control hoods use sash position
sensors to calculate the necessary air volume. Venturi air valves are used to
control the flow of air between the hood and the exhaust network. Either
design drops the air flow through the hood substantially. The hood usually
operates at minimum air exchange, if workers properly close the hood when it
is not in use.

Ventilation plays a key role in the energy consumption as the air that moves
through the fume hood is generally heated and cooled for the comfort and
safety of the occupants.
Department of Facilities –
SAPweb Building Service
Environment, Health & Safety
Office – environment@mit.edu
Take Action - SHUT YOUR SASH!



Regardless of the type of Fume Hood your lab uses, Shut the Sash
Post stickers to Shut the Sash on fume hoods as a reminder
Contact Facilities through SAP to report an equipment operating issue and have it
repaired
GreeningMIT is an initiative of
the Campus Energy Task Force.
For more information visit or
contact:
http://web.mit.edu/mitei/
be-green@mit.edu
Energy Efficient Fume Hood Management Fact Sheet  Page 1
Impact
Department of Chemistry Conservation Program
A campaign to close fume hood sashes within the Department of Chemistry lead to the
following savings:



net savings of about $24,000/yr in energy in building 18
$41,000/yr throughout the entire department
averted approximately 93 tons of CO2 in building 18 and 160 tons of CO2
department-wide
These savings were achieved with approximately $12,000 in initial investment, and
minimal continuing cost.
Resources & Information
Refer to the following websites for more information about energy use from fume
hoods in laboratories:
 MIT’s Closing the Loop: http://sustainability.mit.edu/projects/fume-hoods
 Labs21 2008 Annual Conference – ‘Constant Flow, Variable Flow, and All the
Space Between’ by Jim Coogan, P.E. http://www.i2sl.org/elibrary/coogan2008.html
Visit the following website for ‘Shut Your Sash’ posters and stickers for your lab:
 http://sustainability.mit.edu/resources/tools-and-templates
Energy Efficient Fume Hood Management Fact Sheet Page 2