## 1 Introduction
### Energy Consumption and Carbon Emissions in the Building Sector Worldwide  
Energy use in the building industry contributes to a large proportion of overall energy use in developed countries. Building energy consumption in the EU was 37% of final energy in 2004,and increasing at a rate of 1.5% per annum [6]. Energy use in commercial and residential buildings accounts for 40% of primary energy consumption and is responsible for 24% of GHG emissions [7]. Energy use in the building industry accounted for 39% of overall energy use in the UK in 2004 and the proportion has been increasing annually at a rate of 0.5% since then [6]. The situation with energy consumption in the building industry in other European countries is broadly similar to that in the UK. The energy consumption of the building industry in Spain in 2004 was 23% of total energy use, and the energy demand in the building industry has continued to increase at rate of 4.2% annually [6]. Materials in the construction industry are responsible for 50% of total waste in Germany [8]. Energy consumption in the building sector accounts for 46% of total energy consumption in France [9]. The Department of Energy (DOE) in the United States announced that 41% of primary energy is consumed in the building sector, compared to 30% in the industrial sector and 29% in the transportation sector, whilst the latter are generally considered to be the two major areas of energy consumption [10]. The DOE also reports that building energy consumption is increasing at a rate of 1.9% annually [6]. When considering global energy consumption by the building industry, the energy consumption relating to non-domestic buildings accounts for a huge proportion of the energy use of human activities [11]. The global energy consumption of non-domestic buildings exceeded 1 billion tonnes of coal equivalent (TCE) in 2009 which accounted for 11.4% of total energy consumption in that year [11]. The DOE reported that 46% of energy was consumed in non-domestic buildings in the USA in 2012 [10]. A similar situation has been identified in the UK by the Department of Communities and Local Government (DCLG). According to a survey conducted by the DCLG, non-domestic buildings are responsible for approximately 20% of the UK's energy consumption and carbon emissions [12]. Separate research conducted by [PERSON] shows that energy consumptions in non-domestic buildings is more dominant in urban areas than in other areas in the UK [13]. The energy consumption of non-domestic buildings is also a major contributor to total energy use in other European countries. According Eurostat data published in 2016, the energy consumption from domestic buildings in the EU reduced by 6.51% in 2012 in comparison with 1996 levels, while the energy demand from non-domestic buildings increased by 15.7% over the same period. Among non-domestic buildings, office buildings and retail buildings were the most energy intensive building types and these accounted for over 50% of the total energy consumption of non-domestic buildings in USA, Spain and the UK in 2003 [6]. In the USA, the floor area of office buildings was 17% of the total area of non-domestic buildings and the energy consumption of office buildings was approximately 18% of the overall energy use in non-domestic buildings in 2003. The energy consumption in office buildings accounted for 3.2% of the total consumption in the USA in 2003 [6]. The proportion of energy consumption in office buildings in Spain was notably higher than in the USA, with office buildings accounting for approximately 33% of overall energy use in non-domestic buildings. However, this was 2.7% of the total energy consumption in Spain which is broadly similar to the proportion in the USA. In the UK, the energy consumption of office buildings was about 17% of the energy use in non-domestic buildings and this accounted for 2% of the total consumption in 2003 [6].