Evaluation of demand control ventilation impact on indoor air quality and energy efficiency of an office space

Ventilation is the process of introducing outside air into a building space. Ventilated air is usually heated, cooled, and dehumidified, depending on the weather conditions. The amount of fresh air delivered by the Air Handling Unit (AHU) is proportional to the maximum design occupancy of the building. Even though the space is only partially occupied, the actual occupancy rarely reaches the maximum design occupancy, but the AHU continually operates at the maximum ventilation rate. This frequently leads to excessive ventilation, resulting in higher than necessary energy consumption. This paper proposes to evaluate the impact of Demand Control Ventilation (DCV) on the Indoor Air Quality (IAQ) in an office space and the energy savings achieved through the utilization of DCV. DCV is a control system that regulates the rate of fresh outdoor air entering the Heating, Ventilation, and Air Conditioning (HVAC) system in response to the real demand for ventilation. The amount of ventilation rate is adjusted by DCV based on the number of occupants. This investigation involves two steps: simulation of an office space with a constant ventilation rate, followed by simulation of an office space by utilizing DCV to control the ventilation rate. The actual data of HVAC set point, estimated occupancy, air-conditioned floor area, and estimated electrical equipment load were used as the Carrier Hourly Analysis Program (HAP) input data to simulate the monthly data for electricity consumption and indoor air quality. Through the utilization of DCV, it was possible to maintain the IAQ, while simultaneously reduce the energy consumption by an average of 38.9 %. This approach is more practical and leads to more consistent IAQ; thus, can be used in numerous retrofit or conservation programs