Worldwide, buildings, including residential and commercial buildings, consume approximately 25 per cent of global primary energy, which is responsible for 33 per cent of global CO2 emissions. In more detail, 60 per cent of the world’s electricity is consumed in residential and commercial buildings (Barker et al, 2007). However, there is a wide difference between developed and developing countries and countries from different climatic regions (Laustsen, 2008).