Digi-VAV™ Optimizer
Main Features
- 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
Applications
Buildings: Airport facilities; Office properties; healthcare facilities; schools; universities; fitness centers; conventional and conference centers; food servings and entertainment facilities; and others.
HVAC Units: Single duct variable air volume (VAV) units, Dual duct VAV units, Direct Expansion (DX) or rooftop VAV air handling units.
Principles
Digi-VAV™ measures fan airflow using virtual fan airflow station (Digi-FAS), and CO2 concentrations of the outside, return and supply air. Digi-RTU™ determines the optimal minimum outside air damper position based on DCV principal; the optimal static pressure set point based on fan airflow; and the optimal minimum terminal box airflow based on measured air freshness and occupancy condition by following ASHRAE Standard 62.1 and/or CA Title 24.
For DX roof top units, Digi-RTU™ installs three air property sensors (Digi-APS) to measure temperature, relative humidity, enthalpy, and dew point of outside air, supply air, and return air. Digi-VAV™ determines the compressor sequences to minimize the compressor power, and determines the on and off time to minimize the on and off cycling of the compressor.
Digi-RTU™ communicates with the BAS and updates the optimal set points.
Benefits
- Ensures satisfactory indoor air quality levels in each room
- Decreases heating/reheating energy consumption by up to 30% to 80%
- Lowers cooling energy consumption by 20% to 50%
- Reduces fan power consumption by an average of 40% to 70%
- Increases the compressor efficiency by 30%.
- Reduces compressor cycling by 80%.
- Typical energy cost savings: $0.30 to $0.75/ft2/yr
Case Study
Building Information
134,000 Sq Ft Medical Facility – Omaha, Nebraska
Building HVAC System Information
- Two single duct VAV Air Handling Units
- Over one hundred VAV terminal boxes with hot water reheat
- Siemens BAS System
Annual Energy Savings with Digi-VAV™
- Fan Power: 65%
- Hot water pump: 71%
- Chilled water: 46%
- Steam: 44%
Building HVAC
FAQs
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
Specify Digi-VAV™ Optimizer for your facility
For specifications, pricing, or to scope a deployment, reach out by email.