The Motion and Sash Height Alarm, or MASH for short, was developed by students and staff in the Lab Energy Assessment Center (LEAC) at MIT as a way to encourage energy-saving user behavior regarding chemical fume hoods. LEAC has been working for a few years now to gather data and design this device - in fact, our first iteration of a fume hood alarm and the results we saw using it were published in Energy Reports!

In the summer of 2018, LEAC undergrads and grad students worked to design a new version of the Jetson-based monitor system described in that paper - we were going for something a little less ‘smart’, and a lot more cheap. If we already knew that alarming users as a way to incentivize them to shut their sashes worked - maybe all we needed was a simple gadget that could detect motion and hood position?

After many hours spent researching, designing, developing and testing…..


This streamlined yet “home-built” version of a fume hood alarm utilizes an easy to work with Arduino Uno platform, coupled with a simple IR motion detector and a magnetic binary switch.

The concept is that if the device detects no motion for a set time (default 3 minutes) and the sash is open (more than 1 inch), it will alarm audibly and visually until either motion is detected or the sash is shut.
MASH plugs into a standard 110V hood outlet, and can be installed on any vertical sash in less than one minute.

This all sounds pretty simple and cool, right? But of course the real question in any scientific endeavor is - does it work?

As you can see here:

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It sure does!
In our pilot, monitoring the sash height of 17 hoods in one building, we found:

75% reduction in average sash height
, which translates to over 3,500kWh saved per year, per hood! That’s 3 metric tons of CO2, or $500 in savings!

Check out one group’s results for their 4 fume hoods - imagine this kind of sash height reduction in your own labs!

Check out one group’s results for their 4 fume hoods - imagine this kind of sash height reduction in your own labs!

****It is important to note that all data seen here is not collected or stored by the MASH alarms themselves.
We have piloted and tested this device in buildings which already contain management systems and hardware which measures and records the sash height position over time. ****

Wondering how MASH actually operates in the laboratory? Watch this video to find out! This video is brought to you by the immensely talented MIT UROPs, Ethan Munden and Anupama Phatak.

Now that you know more about the way MASH works… we bet you’re really excited to make your own, for your laboratory! These devices will work on any VERTICAL fume hood - unfortunately, they don’t have as much positive impact on a combination sash with horizontally sliding windows. To reap the benefits of saved energy, you’ll need to install them on a hood with VAV capabilities…however, the increased safety for your users is reason enough to make sure every hood has a MASH!

First off, let’s get you set up to succeed… Click on the icon to the right for a
pre-loaded Amazon shopping cart with everything you need to build 20 MASH alarms.

Below you will find an informative schematic on the wiring and assembly for building a MASH, along with a fun POV instructional video on the assembly and steps involved!

Want to see how easy it is to build your own MASH for use on your fume hoods?

CLick to download the mash wiring schematic

click to download the template for creating the mash box

Finally, the most important component of any programmable device - the programming itself!
These files are INO and are meant to work on an Arduino platform. The one potentially complicated factor here is that there are two types of magnetic sensors that you could potentially purchase: Normally Open, which reads as 0 when the circuit is open (the magnets are not touching) and Normally Closed, which reads as one in this instance. The brand in our Amazon shopping cart is Normally Open, but if you purchase a different type you may need the second program.

CLICK HERE to download the program that works for a “Normally OPEN” magnetic sensor

CLICK HERE to download the program “Normally CLOSED” magnetic sensor

Any questions? Feedback? We want very much to hear from the global community as to how our device is helping to enable energy savings in your laboratory, so please email to let us know of your experience!

Meet the team that made M.A.S.H. a reality!

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Daniel J. Preston

Dan is oft referred to as the Godfather of LEAC (whether he likes it or not), as he founded the center in 2016 with grant money from a GreenLabs/Office of Sustainability competition. We owe it all to Dan!


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Ethan is responsible not only for finalizing and optimizing the MASH design, but creating the majority of the helpful schematics and videos you see above!


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ANupama phatak

Anupama also worked on designing and building the first round of MASH alarms we used in our initial pilot.


Dheekshita Kumar

Dheekshu is one of the first members of the LEAC team, and remains involved with campus energy reduction projects as well as designing the next version of the MASH alarm. Stay tuned!!


Ariel s. anders

Ariel’s computational and programming knowledge was key in making sure that our MASH alarms function properly and predictably.


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Johnathan kongoletos

John’s experience manipulating data and writing research papers has been instrumental in collecting and presenting our findings to the outside world.



Jennifer ballew

As Program Coordinator, Jen doesn’t always contribute much in terms of technical input (whats a Python code??) but she works to reach out to labs at MIT and beyond for feedback and participation.


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Mohamed Ibrahim

Mohamed is a fourth-year PhD student in the Electrical Engineering and Computer Science department. He has been instrumental in designing the updated, easier to assemble version of MASH that will be released soon! Stay tuned!