The difference between actual and calculated energy is called the ‘energy-performance gap’. Possible explanations for this gap are construction mistakes, improper adjusting of equipment, excessive simplification in simulation models and occupant behaviour. Many researchers and governmental institutions think the occupant is the main cause of this gap.
The contribution of buildings to climate change has become widely acknowledged. On 3 December 2015, the United Nations Environment Programme (UNEP) held the first ‘buildings day’ at COP 21 (the UN Climate Change Conference) devoted to the decarbonization of the building stock. There are several forms of negative contributions that buildings make to climate change, but high on the list are embodied and operational energy demands, which largely depend on fossil fuels and result in greenhouse gas emissions.