Measurements of occupancy levels in multi-family dwellings—Application to demand controlled ventilation

The occupancy level of dwellings is an important parameter to know to determine the energy efficiency, energy use and indoor air quality, especially in low-energy buildings where the user-related energy uses, such as household electricity and domestic hot water heating, are significant parts of the energy balance in a building. For residential buildings, there is a lack of occupancy level data, which also needs to be resolved over time, in a way so that both short term and long term variations can be described. As a part of an ongoing study, occupancy levels were measured as building average levels in 18 apartment buildings containing 342 apartments in total with readings every 30 min for more than a year. Averages and standard deviations of occupancy level, and variation in occupancy during the year, week and day respectively are presented. The results show a highly varying occupancy level over time, which indicates the potential of demand controlled ventilation in dwellings.

► A method to continuously measure occupancy level.
► Reference data on typical variations in occupancy levels.
► Improves verifications of user related energy uses.
► Improves prediction of energy use.