3.1 INTRODUCTION Since the large scale industrialization occurred, the profit oriented human activity has led to a constantly growing environmental degradation. Nowadays, that the actual severity of the prob- lem in hand is impossible to ignore and the spectrum of the future consequences emerges in its full extent, several actions towards the adaptation of sustainability principles in the most prob- lematic sectors of human activity are undertaken. One of these sectors is building sector, incor- porating the production, transport, use and replacement of building materials, the use of the building itself (energy consumption for lighting, ventilation, heating and cooling, water con- sumption etc), the reuse of the building or its materials, the demolition of the building and the disposal of the demolition products. The energy consumed in operating buildings serves as indi- cation of the building sector’s contribution to the total environmental aggravation induced by human activity. According to (OECD, 2003), in the European OECD countries, the building sector consumes the highest amount of energy (40%) in comparison to the transport (22%) and industry sectors (38%). Given the fact that the afore-mentioned quantities include the energy amounts consumed only for the operation of the building, while other processes – unbreakably bonded to construction – such as manufacture and transport of building materials, are not co- calculated, an estimation regarding the impact of the building sector on the environment can be drawn. Due to the increasing awareness about the consequence of the contemporary model of devel- opment in the climate change and to the growing international movement toward high- performance/sustainable buildings, more and more the current paradigm of building is changing. This is changing both the nature of the built environment as well the actual way of designing and constructing a facility. This new approach is different from the actual practice by the selec- tion of project teams members based on their eco-efficient and sustainable building expertise; increased collaboration among the project team members and other stakeholders; more focus on global building performance that on building systems; the heavy emphasis placed on environ- mental protection during the whole life-cycle of a building; careful consideration of worker health and occupant health and comfort through all phases; scrutiny of all decision for their re- source and life-cycle implications; the added requirement of building commissioning; and the emphasis placed on reducing construction and demolition waste (Kibert, 2005). Although there are several definitions for a sustainable building, generally speaking, it uses re- sources like energy, water, land, materials in a much more efficient way than conventional buildings. These buildings are also designed and used in order to produce healthier and more productive living, work and living environments, from the use of natural light and improved in- door environmental quality (Syphers et al, 2003). Therefore, sustainable building aims the proper balance between the three dimensions of the sustainable development: Environment, So- ciety and Economy. Building sustainability assessment involves various relations between built, natural and social systems. Therefore it comprises hundreds of parameters, most of them interrelated and partly Chapter 3 – Use of rating systems in the process towards sustainable construction Coordinator: Ricardo Mateus Contributors: Ricardo Mateus, Luís Bragança, Rijk Blok, Mauritz Glaumann, Christian Wetzel, Dimitrios Bikas, Christina Giarma, Ilker Kahraman, Yesim Aktuglu ______________________________________________________________________________________________________ Part I – Integrated Methods for Sustainable Constructions 51