Friendly “shut the sash” feedback

When you leave a freezer door ajar in your kitchen, what happens? The refrigerator beeps, right? This warning is a simple and effective signal to avoid a problem. Behavioral scientists might describe that “beep” as an auditory prompt. It’s a cue to help people extinguish an unwanted behavior. The MASH alarm works in a similar way. The device beeps after no motion is detected for three minutes at a hood when the sash has been left too far open.

The chart below from MIT Green Labs demonstrates a clear trend. The MASH alarm helps people to remember to close sashes. This allows labs to quickly save tons of energy! MIT has published two studies on the utility of the MASH alarm: The use of feedback in lab energy conservation: fume hoods at MIT and Active fume hood sash height monitoring with audible feedback. More recent observations have shown that the MASH alarm effect is long lasting. In other words, people in the lab don’t start ignoring the device over time.

Safe and economical

Scientists know that fume hoods are important for lab safety. This equipment protects users from hazardous chemicals, using a combination of air flow and physical barriers. Hoods can account for up to 50% of lab energy usage. While many scientists use hoods on a daily basis, there are many different kinds of hoods. Researching “best practice” for energy consumption for each type of hood is time consuming. However, it’s worthwhile to know that a variable-air volume (VAV) hood is designed to provide a constant temperature air flow and that this type of hood reduces air draw from the room when the sash is closed. With a MASH alarm scientists can safely automate energy efficient use of VAV hoods and synergistic-ally affect HVAC room air exchange systems - without distraction from lab work

The other great part about the MASH device is that it is economical. It only costs around $32 to assemble a MASH alarm. On average this device saves 3,500kWh of electricity (~$500 USD) and 3 metric tons of CO2 per year.

Please check out MIT Green Lab’s MASH Alarm web page for the “How to” video and a pre-loaded Amazon cart.

Don’t fume hoods outfitted with an automated sash closer already solve this problem?

Yes and no. The answer depends on the lab type. Certainly fume hoods with automatic sashes are used in many labs, especially in industry. A variable-air volume (VAV) hood with an automatic sash will save 30% of energy over its life time. The problem is that these hoods don’t match the safety needs of many academia labs. Environmental Health and Safety departments must ensure the safety of people new to the lab, in a transient scientist population. The average work time spent in an academic lab is only ~2 years. An automated hood sash is far more likely to surprise a grad student returning a flask of a hazardous substance to the hood, from the bench. A grad student is also more likely not to be wearing gloves, a lab coat or goggles when it happens. Therein lies the issue.

What is the feedback from scientists?

Scientists have been impressed with how well the device integrates into lab work. MIT lab managers report ease of use and no complaints. MIT green labs coordinator Jennifer Ballew says that a couple of labs whose devices were accidentally damaged requested replacements, which speaks to the MASH alarm’s value in labs.

Please consider conserving energy in your lab by building and installing a MASH alarm. Not only will you be reducing your lab’s environmental impact, but you will also be using science funding responsibly. Best wishes to all!

“All of the labmates gave me good feedback!  When people use the hood and then they need to work back on their bench, it is easy to forget to shut the sash.  MASH alarms give us reminders, so that we can always keep the hoods closed and save energy!”

- Xiuyun Hou, Hammond Lab Manager, MIT Dept. of Chemical Engineering