One problem in today’s indoor air quality lies within insufficient ventilation. Dynamic ventilation can be obtained by implementing a Demand-Controlled ventilation (DCV) system. DCV systems adjust the ventilation in a building by calculating the impact made by its’ occupants. This is done by sensors, the most common one are carbon dioxide sensors. A different solution would be to calculate the number of occupants and then calculate the carbon dioxide levels from that number. This paper describes the development of a sensor fusion system for presence detection. The system will be using sensors that have been proved being able to detect human presence. Results show that the system detects presence in 97.5 % of the given cases. The system also detects the number of occupants with an error of 1.77 %.