Why Should You Install VFD?

Managing a building or facility in today’s highly competitive market requires you to fulfill multiple goals simultaneously such as ensuring everything operates smoothly, enhancing occupants’ comfort level, being environmentally responsible as well as reducing operational costs. Since the HVAC system is an important component of a building system as well as a major energy consumer, certain additions or modifications can make it more efficient and also bring down energy costs. Once such addition is installing VFD or variable frequency drive on your HVAC unit. In this article we take a look at what exactly are VFDs and how they work better together with your commercial HVAC system.

What is VFD or Variable Frequency Drive?

Usually, HVAC systems are set up to function at a constant speed irrespective of the demands. However, in practice, the actual building load demand on HVAC systems constantly fluctuates. A VFD also known as AFD – adjustable frequency drive – allows such systems to adjust the speed at which the motor runs and is dependent on how much power the mechanical systems require to fulfill the demand of the building which is also referred to as the “load” of the system.  By changing the speed, the motor can meet the building load demand without spending extra energy and reducing energy costs.

Most of the time, HVAC systems only need to work at peak load 1 to 10 percent of the operational time- which means a VFD is able to reduce the amount of energy wasted during more than 90 percent of the operational time. With the installation of VFD on the HVAC system, you can see energy savings by more than 50%. With that being said, here are some of the top reasons why you should install VFD on HVAC system:

Energy savings – VFDs produce significant energy savings. This is because motor energy consumption is a function of speed and the most common motor in HVAC systems is the induction motor. For induction motors, the power used by the motor differs with the cube of the motor’s speed. This means that if the motor can be reduced by 25 percent of its regular operating speed, its energy use can be lowered by almost 60 percent and with a 50 percent decrease in speed, energy use can be reduced by almost 90 percent which translates into significant energy savings and reduced energy bills.

Lower demand charges- Another benefit of installing VFD on HVAC is that since it reduces energy use of the building system during its peak demand period, it will also mean reduced demand charges. This will also reflect on reduced electricity bills.

Increased lifespan of the system – A VFD allows the motor to start softly rather than all at once unlike regular motors which means less energy is spent to start the motor. This ultimately reduces wear and tear on the motor, thereby increasing the lifespan of the system.

Less repair costs- Again, due to the soft start and reduced wear and tear on the motor, less frequent repairs are needed, reducing repair costs. In addition, it also lowers chances of motor failures. 

More precise control over flow rates – Another advantage of using VFD is that it gives exact control over a range of flow rates. For example, the flow rate generated by pumps in building HVAC systems can be adjusted to the building load through the use of a VFD. This reduces load on motor, wear and tear on pump, as well as energy use. 

In addition, VFDs can also be used in other applications such as hot and cold water systems to maintain a constant pressure irrespective of demand levels. This also helps in preventing water leaks or pipes bursting due to high pressure.

Maximize efficiency – Most HVAC systems are designed to handle extra loads such as new parts or a greater number of people. With VFD, you can get a more exact assessment of motor load and speed which ensures optimum efficiency of the system.

Deliver diagnostic data– With VFD, you can get constant updates on how the HVAC system is functioning. As a result, you can track and monitor any defect early on before it becomes a major problem and prevent costly repairs. 


A VFD is a diverse and hugely beneficial energy management tool that has a wide range of applications. Today’s VFD can be installed on any commercial or institutional HVAC system and can offer significant energy savings of from 35% to 50% and result in a return on investment of six months to two years. A-TECH Engineering Ltd. – a leading HVAC controls contractor in Toronto can help you with setting up VFDs, upgrading HVAC controls, efficient coil cleaning and more for improved efficiency and maximum energy savings. Connect with us today!