Variable air volume (VAV) air handling units (AHU) are the primary AHU for office building air conditioning. However, the following problems are not uncommon:

• Excess airflow results in the excessive consumption of heating /cooling energy consumption
• Fixed outdoor air intake ratio at AHU level
• Fixed minimum air flow rates at the terminal box level
• Cannot guarantee fresh air requirement levels are achieved
• Poor building pressure control
• Compressor hunting for DX units
• High installation and ongoing maintenance costs due to the need for individual CO₂ sensors

 Digi-VAV^® Solutions:

• The indoor air quality requirements are satisfied by resetting the  minimum airflow for each zone based on the zone occupancy schedules and supply air quality
• The outdoor air intake ratio is reset based upon the building occupancy conditions
• The static pressure is reset based upon the fan airflow
• The floating compressor staging is used to prevent compressor hunting
• The building pressure is maintained properly using volumetric tracking return fan 

• Decreases heat/reheat energy consumption by about 30 – 80%
• Lowers cooling energy consumption by about 10 – 25%
• Reduces fan power consumption by about 30 – 50%
• Ensures  adequate indoor air quality, zone thermal control, and building pressures
• Complies with ASHRAE Standard 62.1 & CA Title 24 air quality requirements
• Eliminates the need for individual CO2 room sensors

• Virtual fan airflow stations: Measures the true supply and return airflows. 
• CO2 Sensor: Measures the supply air CO2 concentration level.
• Reset the Terminal Box Min Airflow: Resets the minimum airflow at each terminal box based on the supply air CO2 concentration.
• Optimizes the AHU outside air intake: Integrated enthalpy economizer and CO2 based demand ventilation control.
• Minimize Supply Air Fan Power: Reset the supply air static pressure setpoint based on fan efficiency and airflow.
• Minimize Return Air Fan Power: Control fan speed based on volumetric tracking.  

• Reset the terminal box minimum airflow based on the supply air CO₂ concentration. This ensures the fresh air requirements are met under design occupancy conditions at all times while significantly reducing the minimum airflow.
• Use fan airflow technology to measure both supply and return fan airflow.
• Reset the supply air static pressure based on airflow to minimize duct resistance and reduce fan power consumption.
• Control return airflow by tracking the supply airflow to maintain proper building pressure

• How does the Digi-VAV^®save energy?

The Digi-VAV^® dynamically resets the minimum airflow of each terminal box based on the supply air quality and the occupancy status. This allows for a lower and more accurate minimum airflow set-point, thus reducing unnecessary heating and cooling at the terminal box

The Digi-VAV^® dynamically resets the supply static pressure based on the measured building load.  It also lowers the set-point to allow the fan to run at lower speeds

• Does the Digi-VAV^®control the staging of the compressors?

Yes

• Does the Digi-VAV^®controller replace the existing AHU controller or terminal box controller?

No, the controllers remain

• Does the Digi-VAV^®communicate with the AHU controller or terminal box controller?

No, the Digi-VAV^® communicates with the BAS controller thus providing the revised set-point for the supply static pressure, return air fan speed, minimum OA damper, and terminal box minimum airflow

• Do the existing supply fan VFDs need to be replaced?

No, they do not need to be replaced

• Where is the Digi-VAV^®mounted?

The Digi-VAV^® is mounted inside the mechanical room next to the AHU

• How long does it typically take to install a Digi-VAV^®unit?

It takes approximately 3 hours to mount a Digi-VAV^® and 30 minutes to program each terminal box