To achieve indoor air quality (IAQ) the right amount of ventilation air must be delivered and the exhaust removed from the occupied space. A constant flow ventilation system will deliver the ventilation air once properly balanced by a professional test and balance contractor. While IAQ may be achieved with a constant flow system the energy use, carbon impact and operating cost will be high.

The solution is to advance to a demand control ventilation (DCV) system. By adding active airflow control to the design, it is now possible to deliver just the right amount of ventilation air to achieve IAQ based on real time-space use. The rest of the time, the reduced airflow will deliver improved energy usage, low carbon emissions and reduced cost. To deliver DCV, an active airflow control system is used where each zone is controlled either by an occupancy, VOC, or CO2 sensor (See Fig. 1).

FIG. 2 shows actual ventilation airflow data and energy usage for an office building in Sweden. The system delivered the necessary IAQ while reducing the airflow on average to 42% of the design ventilation requirement resulting in greatly reduced energy use, carbon impact and operating cost. Real-world experience supports the demand control opportunity.