Definition:
Demand-Controlled Ventilation: Demand-Controlled Ventilation (DCV) is an intelligent HVAC strategy that adjusts the amount of outside air introduced into a building based on real-time occupancy levels or air quality measurements. By continuously monitoring factors such as CO2 concentrations or occupancy sensors, DCV systems optimize ventilation rates to maintain indoor air quality while minimizing energy consumption and operational costs.
Additional Facts
- CO2 Sensors: Demand-Controlled Ventilation systems typically use carbon dioxide sensors to monitor occupancy levels and adjust ventilation rates accordingly.
- Energy Savings: DCV can significantly reduce energy consumption by minimizing the over-ventilation of spaces during periods of low occupancy.
- IAQ Improvement: By dynamically adjusting ventilation rates based on actual occupancy, DCV helps maintain optimal indoor air quality and occupant comfort.
- Integration: DCV systems are often integrated with building automation systems (BAS) for seamless control and monitoring of ventilation alongside other HVAC components.
- Code Compliance: Many building codes and standards, such as ASHRAE 62.1, recognize DCV as an acceptable method for meeting ventilation requirements in variable occupancy spaces.
Fundamental Mechanisms
| Mechanism | Purpose | Key Components | Critical Issue | Impact of Failure |
|---|---|---|---|---|
| CO2 Sensors | Monitor indoor air quality and occupancy levels | CO2 sensor, signal processor, calibration system | Sensor drift and calibration inaccuracies | Improper ventilation rates, energy waste or poor air quality |
| Damper Control System | Regulate airflow based on CO2 levels | Actuators, dampers, control board | Mechanical failure or control signal issues | Inability to adjust ventilation, leading to over/under ventilation |
| Variable Frequency Drive (VFD) | Adjust fan speed to match ventilation demand | Inverter, control circuit, cooling system | Electronic component failure or overheating | Fixed fan speeds, reduced energy efficiency, system strain |
| Building Automation System (BAS) | Integrate and manage DCV with other building systems | Central processor, network infrastructure, user interface | Communication failures or software glitches | Loss of system coordination, manual intervention required |
| Air Handling Unit (AHU) | Condition and distribute air based on DCV input | Fans, coils, filters, mixing box | Component wear, filter clogging, coil fouling | Reduced air quality, increased energy consumption, comfort issues |