The occupants' behaviour has a great influence on the energy demand, management and consumption of a building. This paper investigates the influence of three parameters related to human behaviour through their modes of occupations (based on family size, management of the heating system and management of the heated area) on the housing heating loads of a standard dwelling in Belgium. Seven levels of insulation were tested: no insulation, two intermediate levels corresponding to 3 and 6 cm of insulation, the current standard for new buildings in Belgium, the low energy standard, the very low energy standard and the passive house standard. Multi-zone simulations were performed with a dynamic thermal simulation software. The impact of occupants' lifestyle and the interactions between occupation modes and insulation levels are highlighted. These results prove that the more the building is insulated, the more the lifestyle proportionally influences the heating loads. One important strategy for reducing heating consumption during the whole life cycle of the building is adapting the size of the house and its occupation modes to the evolution of family size. However, insulation is paramount, and increasing the insulation of the house provides generally better results than merely adapting the occupation mode. (c) 2012 Elsevier B.V. All rights reserved.