The ventilation rate inside a building is directly dependent on the number of occupants in the space. If we had the ability to economically count each person as they enter and exit the space, then we could provide exactly enough ventilation air to meet the needs of the quantity of people in the space. But in most buildings occupancy is not tracked in real-time and therefore finding the right balance in ventilating your building is a challenge.

Most HVAC engineers and designers design ventilation system on the maximum anticipated building occupancy. This results in a waste of energy and money, due to over-ventilation during lean periods. Demand Control Ventilation (DCV) is a ventilation control strategy that provides just the right amount of outside air the humans need, and no more. This accomplishes two things. First it saves energy by not heating or cooling unnecessary quantities of outside air. Secondly, it can provide assurance that sufficient outside air is being supplied for the number of occupants present.

This 4-hr course provides the framework necessary for integrating DCV into a HVAC system and includes background on ASHRAE ventilation standards. The course will take reader through the design process and calculations needed to understand, how to properly implement DCV strategy.

Learning Objectives

• What is demand-controlled ventilation (DCV)?
• How is DCV different from fixed ventilation strategy?
• Which spaces would benefit most from DCV?
• What is CO₂ based ventilation and what is the relationship between CO₂ and the outside airflow rate into the space?
• How do you determine whether your space is appropriate for DCV?
• How to estimate the minimum ventilation rate and the base ventilation rate for non-occupant related sources?
• What are the primary differences between the ASHRAE 62-(1989 thru 2001) standards with ASHRAE 62-2004 standard?
• What type of CO₂ sensor specifications is appropriate for the ventilation control?
• What is the ideal location of CO₂ sensors for constant volume and variable volume systems? How quantity of CO₂ sensors is determined?
• What are the commissioning requirements for CO₂ based DCV?
• What are the important design issues that need to be accounted in design of CO₂ based DCV?
• What important building codes/standards other than ASHRAE apply to DCV?