What is Demand Controlled Ventilation (DCV)?
Demand Controlled Ventilation (DCV) is an energy-efficient system that adjusts the ventilation rate in a building based on real-time occupancy. Using sensors to monitor CO2 levels, DCV optimizes airflow by decreasing ventilation during low-occupancy periods. This intelligent approach ensures a comfortable and healthy indoor environment while minimizing energy waste and reducing operational costs. DCV is commonly used in commercial buildings, schools, and spaces with fluctuating occupancy levels.

XCSpec’s Smart Ventilation system implements a Demand Controlled Ventilation (DCV) strategy that adjusts the amount of outdoor air ventilation based on the current demand in a space. The primary goal is to minimize energy consumption.

Why do you need to consider DCV?
Building codes mandate ventilation opening requirements are based on the building’s use (gym vs. office) and the maximum number of people the space is designed to hold. When a building is OCCUPIED, if a DCV strategy is not employed, the ventilation settings go to a full occupancy ventilation setting, independent of how many or if any people are present. Depending on the outside air condition, it is most likely that the new air introduced must be conditioned (heated, cooled, or dehumidified) for the space temperature and humidity needs.

The picture below shows a building running on a fixed occupancy schedule with No DCV. During the day anywhere from 1 to 25 people are occupying this space. Since this is on a fixed occupancy schedule, the building ventilation is at the maximum occupancy setting from opening time to closing. The amount of new air being introduced is represented by yellow. This air will need to be reconditioned throughout the day, including heating in the morning and cooling and dehumidifying later in the afternoon. Reconditioning the air incurs significant operating costs.

If an occupancy-based sensor is used, the ventilation opening changes, as shown below. However, note that ventilation fluctuates between the minimum and maximum settings. The amount of new air being introduced is represented in blue. Although this is reduced, since the space is never at maximum occupancy, we are still reconditioning air unnecessarily and wasting significant energy.

If the XCSpec DCV solution is used, the figure below shows that the ventilation openings align with building occupancy. This is determined by measuring CO2 levels in the building spaces. The measured CO2 data is sent to an Economizer Control, which adjusts the input air damper or PI, managed by the AQ Extender. As shown, this results in little to no wasted energy.

When a building utilizes XCSpec’s Smart Demand Controlled Ventilation (DCV) strategy, it adjusts the outdoor air ventilation based on the current demand in the space. The primary goal is to minimize energy consumption.

DCV systems dynamically regulate ventilation rates based on occupancy levels or indoor air quality indicators. Sensors monitor real-time data, and the ventilation system responds accordingly.

1. Continuously measuring environmental factors: AQ TstatPro Plus and AQ Indoor with CO2
   - CO₂ Sensor: Detect carbon dioxide levels as a proxy for occupancy.
2. Communicates up to 4 zones of environmental Factors
   - CO₂ Control: The highest CO2 readings from all zones are sent to the AQ Extender
3. Control by the AQ TstatProPlus
   - Selectable 0-10 or 2-10V output to the economizer controller
   - Control is based on the highest CO2 ppm from all zones.
   - DCV output range is configureable at install.
   - PPM High - sets the high PPM input for the DCV output = 10 volts.
   - PPM Low - sets the low PPM input for the DCV output = 0 volts or 2 volts (if 2-10V is selected).

1. Energy Savings:
   - Reduces heating, cooling, and fan energy costs by avoiding over-ventilation during low occupancy.
   - Particularly impactful in spaces with variable occupancy, such as offices, school, auditoriums, and gyms.
2. Improved Indoor Air Quality:
   - Responds dynamically to pollutants and CO2 levels, maintaining a healthier indoor environment.
   - Reduces potential for sick building syndrome (SBS).
3. Compliance:
   - Meets vuilding codes like ASHRAE 62.1, Title 24, or local ventilation standards.
4. Sustainability:
   - Lowers the buildings carbon footprint by optimizing energy use.