Demand-controlled ventilation in new residential buildings : consequences on indoor air quality and energy savings

Abstract

The consequences on indoor air quality (IAQ) and potential of energy savings when using a variable airvolume (VAV) ventilation system were studied in a newly built Swedish building. Computer simulationswith IDA Indoor Climate and Energy 4 (ICE) and analytical models were used to study the IAQ andenergy savings when switching the ventilation flow from 0.375 ls1m2 to 0.100 ls1m2 duringunoccupancy. To investigate whether decreasing the ventilation rate to 0.1 ls1m2 during unoccupancy,based on Swedish building regulations, BBR, is acceptable and how long the reduction can lastfor an acceptable IAQ, four strategies with different VAV durations were proposed. This study revealedthat decreasing the flow rate to 0.1 ls1m2 for more than 4 h in an unoccupied newly built buildingcreates unacceptable IAQ in terms of volatile organic compounds concentration. Hence, if the durationof unoccupancy in the building is more than 4 h, it is recommended to increase the ventilation rate from0.100 ls1m2 to 0.375 ls1m2 before the home is occupied. The study showed that when the investigatedbuilding was vacant for 10 h during weekdays, increasing the ventilation rate 2 h before occupantsarrive home (low ventilation rate for 8 h) creates acceptable IAQ conditions. In this system, theheating requirements for ventilation air and electricity consumption for the ventilation fan weredecreased by 20% and 30%, respectively.QC 20150429</p