Smart home implementation in residential buildings promises to optimize energy usage and save significant amount of energy because of a better understanding of user’s energy usage profile. Apart from the energy optimisation prospects of this technology, it also aims to guarantee occupants comfort and remote control over home appliances both at home locations and at remote places. However, smart home spending requires an adequate measurement and justification of the economic gains it could proffer before its realization. These economic gains could differ for different occupants due to their inherent behaviours and tendencies. Thus it is pertinent to investigate the various behaviours and tendencies of occupants for similar domain of interest and to measure the value of the energy savings accrued by smart home implementations in this domains of interest in order to justify such economic gains. This paper investigates the energy consumption in rented apartments for two behavioural tendencies (Finland and Germany) obtained through observation and corroborated by conducted interviews. These tendencies alongside the energy measurements from the smart home system is used to measure the payback time and Return on Investment (ROI) of their smart home implementations. The research finding reveals that building automation for the Finnish behavioural tendencies seems to proffer a better ROI and payback time due to a relatively higher energy usage for space heating during the dark winter times.