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Demand Controlled Ventilation
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Demand Controlled Ventilation

April 18, 2011


Ventilation is required so that the human occupants in buildings are provided with fresh air. The purpose is to provide oxygen and dilute other gases such as CO2 and human odors.

DCV is a ventilation control strategy that provides just the right amount of outside air that is needed by the occupants. Active control of the ventilation system can provide the opportunity to control indoor air quality. It can save energy. Demand-controlled ventilation adjusts outside ventilation air based on the number of occupants and the ventilation demands that those occupants create. DCV is part of a building's ventilation system control strategy. It is an integral part of a building's ventilation design.

CO2 sensors are best suited for highly variable occupancy in larger assembly spaces. They are an accepted method of determining occupancy for the purpose of controlling ventilation. The larger space (and volume) will allow the concentration of contaminants to grow more gradually. CO2 sensors take a little time to respond to changes in the environment. As the occupancy changes, the ventilation can easily keep up.

The largest benefit of CO2-based DCV is that the ventilation system can manage a wide range of occupancy and respond accordingly. This saves energy as well as providing good ventilation during peak periods. Single rooms, with single or multiple air handling systems are the most easily controlled.

EcoFresh CO2 Sensors

CO2 is used as a surrogate ventilation index for measuring Indoor Air Quality in PPM level. As the number of people in the building increases or the level of activity goes up, so will be the CO2 concentration. High Concentration of CO2 indicates poor Indoor Air Quality (IAQ) which causes drowsiness, discomfort and an inability to retain information and respond . . . low productivity..

EcoFresh CO2 Sensor detects and displays the parts per million (ppm) of CO2 in the air. The unit may be mounted on a wall or ceiling of the occupied spaces of a building or in an aspiration box attached to the return air duct.

CO2 control provides a good balance between comfort control and energy savings by assuring an adequate amount of fresh air based on actual occupancy. CO2 Sensor controls the ventilation system according to ventilation requirements (ASHRAE standard 62).

EcoFresh CO2 ideal for Monitoring IAQ in:

  • Office buildings
  • Conference Halls
  • Retail Stores
  • Restaurants, Pubs
  • Dry Ice Facilities
  • Ware Houses
  • Green Houses
  • Animal Houses
  • Theatres
  • Museums
  • Schools
  • Hospitals

ASHRAE* Recommended Ventilation Rates Rates / Person Ventilation Application cfm (cmh)

Office Space 20 cfm (34)
Resturants 20 cfm (34)
Bars 30 cfm (51)
Conference Rooms 30 cfm/room (51)
Auditoriums 15 cfm (26)
Classrooms 15 frm (26)
Patient Rooms 30 cfm (43)


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