How Do Thermally Actuated Diffusers Conserve Energy in Commercial Buildings?
by Mike Collins |

With HVAC systems and fans comprising over 35% of a building’s overall energy consumption, it’s imperative to incorporate energy-saving devices into the HVAC system design. Thermally Actuated Diffusers are useful devices to help conserve energy while creating more comfortable environments.


What are Thermally Actuated Diffusers?


Thermally Actuated Diffusers are air diffusers that incorporate a thermal actuator that can operate the diffuser using only a difference in temperature, usually within a couple of degrees. There are a few types of thermally actuated diffusers on the market, but the majority of them can be broken down into two main categories:


  • Thermally actuated diffusers that regulate the quantity of airflow. These types of diffusers are usually square ceiling diffusers or linear slot diffusers that incorporate a damper and a thermally actuated mechanism that will restrict airflow that gets above or below a specific temperature. Thermally actuated square ceiling diffusers from Greenheck would be models XG-MSC or XG-MSCVH.

Greenheck Thermally actuated square ceiling diffusers - MSCVH

MSCVH Cutaway



  • Thermally actuated diffusers that control the direction of airflow. These diffusers change the direction of airflow depending on temperature which is a highly effective method to reduce thermal stratification (i.e., when the temperature near the ceiling is much higher than the temperature near the floor). During the heating mode, the product changes the airflow orientation to be vertical in order to enhance the mixing of the air in the room and stabilize the temperature throughout the space. In cooling mode, the product uses a horizontal airflow direction to enhance the mixing of the cool supply air into the room. Using a thermally actuated diffuser like this decreases the amount of time required to condition a room and also saves substantial amounts of energy. An example of this type of thermally actuated diffuser is the Greenheck XG-MLAD linear anti-stratification diffuser.
Greenheck XG-MLAD linear anti-stratification diffuser


An Energy-Efficient Solution


In addition to helping reduce thermal stratification as mentioned above, thermally actuated diffusers that regulate airflow can also provide an energy-efficient solution to another frequent problem with air conditioning systems, which is having certain zones with inadequate cooling or heating. This can lead to local discomfort of occupants and can decrease productivity in an office environment. For example, if an occupant in a zone is not comfortable, they can adjust the thermally actuated diffuser in their zone to have a different temperature set point. By doing this, the occupant can change the amount of cooling or heating provided to that area by increasing or decreasing the amount of conditioned air in that space, which will improve their comfort level. Typically, this is accomplished with VAV systems and electric thermostats, or other electronic control methods. However, a thermally actuated diffuser can accomplish the same benefits without using any electricity.


Thermally actuated diffusers are extremely useful in reducing energy costs for large buildings. Consider using thermally actuated diffusers to improve energy efficiency and occupant comfort in your commercial building projects.

Click here for more information on Greenheck thermally actuated diffusers or contact your nearby Greenheck representative.

Grilles, Registers & Diffusers

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Mike Collins
Mike Collins
Mike Collins
Mike Collins is a Segment Engineering Manager for grilles, registers, and diffusers (GRD) at Greenheck. Mike holds a bachelor’s and master’s degree in mechanical engineering from Florida State University with an emphasis on heat transfer and fluid dynamics.
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