Drives for fans in commercial buildings

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Optimize comfort and energy consumption in building ventilation

With user-friendly interfaces, distributed intelligence and reduced power consumption, Danfoss AC drives optimize the performance of fans.

The VLT® HVAC Drive and VLT® Refrigeration Drive convert velocity pressure sensor values into flow values, enabling setup based on fixed flow or fixed differential flow. This optimizes both comfort and energy consumption. To improve comfort levels even further, drives connected to fans can be set to avoid the frequency bands which create resonance and damage in the ventilation system.

Extended building management system capacity

When integrated into a building management system network, to extend the capacity of the controller, all HVAC drive I/O points are available as remote I/Os. For example, room temperature sensors (Pt1000/Ni1000) can be directly connected to the system. 

Improved air-handling performance

The VLT HVAC Drive and VLT Refrigeration Drive are fitted with a built-in Smart Logic Controller and four auto-tune PID controllers to control air-handling functions with fans, valves and dampers. The direct digital controllers of the building management system are released and valuable data points are saved lowering air-handling costs.

The VLT HVAC Drive handles logical rules and input from sensors, real-time functionality, and time-related actions. This enables the AC drive to better control a wide range of functions:

  • Weekend and working day schedules
  • Cascaded P-PI for temperature control
  • Flow balancing between fresh and outlet air
  • Belt monitoring – from the relation between current and speed, the AC drive is able to reliably recognize a broken belt. Lack of air flow is detected immediately so that action can be taken to reduce costs and downtime 

Safety in hospital ventilation

Hospital ventilation has strict requirements regarding safety, compliance and efficiency. Danfoss provides AC-drive solutions for fire and smoke safety, heat dissipation, harmonic mitigation, and EMC and seismic compliance.

Fail safe with no trips

In hospitals, failure for any reason can jeopardize lives. Drives powering pumps and chillers must be extremely reliable and virtually immune to mains supply disruptions. To achieve this reliability, Danfoss AC drives are designed to ignore voltage sags and even short outages, maintaining full performance at all times.

Protect applications and operators 

The VLT® HVAC Drive FC 102 provides the STO (Safe Torque Off) function in compliance with ISO 13849-1 PL d and SIL 2, according to IEC 61508 / IEC 62061. In high demand applications, this can be expanded with the VLT® Safe Option MCB 140, an external module that provides functions such as Safe Stop 1 (SS1), Safely Limited Speed (SLS) and Safe Maximum Speed (SMS), control of external contactors and safety door monitoring and unlocking.

Reliable harmonic mitigation

While AC drives increase precision, save energy and extend application lifetime, they also introduce harmonic currents to the hospital grid. If not kept under control, harmonic currents can affect the performance and reliability of generators and other equipment.

To ensure minimal disturbance, read more about our harmonics application know how, software tools and harmonic mitigation solutions.

Tunnel ventilation

Metro and motorway tunnel operators demand strict ventilation performance for safe operation and optimized cost of ownership. The VLT HVAC Drive offerings, from low to high power, fulfill smoke and fire safety requirements and comply with seismic regulations. All our units offer the same HVAC-dedicated functionalities, standards compliance and compatible soft starters, filter and fieldbus communications options.

Airport ventilation

With hundreds of thousands or even millions of passengers annually, ventilation is a top priority for international airports. To improve traveler comfort and safety, and to combat rising electricity prices, drives are increasingly being used to control and optimize the operation of air-handling units and reduce energy consumption.

VLT HVAC Drives extend from low- to high-power solutions. They come equipped with HVAC-dedicated functionalities and compatible soft starters and filters for EMC and harmonics mitigation. And the complete range of fieldbus communications options enables effective integration with the building automation system.

EC+ Concept

When building an HVAC system, to get the highest performance and system efficiency, the individual components – motor, drive and fan – need to be flexible and broadly compatible with each other. For instance, if you specify a high-efficiency motor that is only compatible with lower efficiency fans, the overall system efficiency would suffer and would not reflect the high performance – and investment – in the individual components.

Danfoss Drives’ EC+ concept allows ventilation system designers to combine a VLT® HVAC Drive with the most efficient fan and permanent magnet motor.

Advantages of the EC+ concept

  • Free choice of motor technology: PM, asynchronous or synchronous reluctance with the same AC drive 
  • Device installation and operation remain unchanged
  • Manufacturer independence in the choice of all components
  • Superior system efficiency thanks to a combination of individual components with optimum efficiency
  • Retrofitting of existing systems is possible
  • Wide range of rated powers for standard, PM and synchronous reluctance motors

World’s greenest hotel uses 60% less electricity

Designed for sustainability, Crowne Plaza Copenhagen Towers is truly engineering tomorrow, with 60% lower electricity consumption than comparable hotels operating conventional energy technology, in 2015. Deploying the best environmental and energy technology, the hotel comes close to achieving carbon neutrality.


  • DrivePro® Life Cycle Services

    Every AC drive application is different. DrivePro® Life Cycle Services is a collection of tailor-made products designed around your needs.

    From optimized spare part packages to condition-monitoring solutions, customize our products to support your business through the different stages of your AC drive’s life cycle.

  • Enhanced VLT® HVAC Drive FC 102
    VLT® HVAC Drive FC 102

    This tough and savvy FC102 drive enhances pump and fan applications in building management systems, and runs outdoors in most climates.

  • VLT® Refrigeration Drive FC 103
    VLT® Refrigeration Drive FC 103

    FC103 is dedicated to controlling compressors, pumps and fans for significant energy savings in refrigeration plants.

  • VACON® 100 FLOW
    VACON® 100 FLOW

    Dedicated functionality that improves flow control and saves energy in industrial pump and fan applications.

Case stories

  • Danfoss ensures sustainable luxury in the heart of Sønderborg

    DENMARK: Hotel Alsik is proud to be 76% CO2-neutral, with sustainable solutions reflected throughout the entirety of this magnificent hotel – from the energy-efficient solutions in the hotel rooms, the design of the building and the power supply, to the 380 m2 solar cells on the roof.

  • Cool tech for ice hockey ensures perfect match conditions
    Cool tech for ice hockey ensures perfect match conditions

    When talking about ice hockey arenas, whether you are a player or a spectator, you’re always on the winning team with Danfoss.

  • Equinix server rooms – Totally reliable air conditioning
    Equinix server rooms – Totally reliable air conditioning

    Equinix connects the world’s leading businesses to their customers, employees and partners inside the most interconnected data centers.

  • Copenhagen Cityringen – Tight spaces made manageable
    Copenhagen Cityringen – Tight spaces made manageable

    Cityringen brings a new, completely automated underground line to the center of the Danish capital.

  • Danfoss building technology: reliability at its best
    Danfoss building technology: reliability at its best

    Three departments, one solution: the reliability of Danfoss building technology took centre stage at the newly build eye clinic in Tübingen. Danfoss components meet the highest requirements of medical centres, while being reliable and energy efficient.

  • World’s greenest hotel uses 60% less electricity
    World’s greenest hotel uses 60% less electricity

    VLT® HVAC Drive helps Crowne Plaza Copenhagen Towers hotel optimize energy efficiency and cost effectiveness.

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