عملکرد محیطی سازه های چوبی مختلف برای سقف های شیبدار Environmental performances of different timber structures for pitched roofs

1. Introduction Considering and fulfilling the dimensions of sustainability represent the most important challenge for humankind at the beginning of the 21st century. The climate change phenomena registered in the last decades have led to a growing public awareness regarding the critical situation that current generations have to confront. Conjointly, the current rates of natural resources consumption are considered to be unsustainable, jeopardizing the Earth’s capability of fulfilling our basic needs in the future. Therefore, in order to minimize the negative effects of our daily activities over the Earth’s ecosystem, and to offer an equitable chance at development for the next generations, society as a whole must drastically reduce the volume of raw materials used and the amount of emissions to the natural environment, and at the same time increase the number of applications/technical solutions which make use of renewable resources. Taking into account the amount of raw materials and energy consumed in the construction sector, and the volume of greenhouse gases emitted from the various processes that are specific to the built environment, this industry justifiably represents a key factor in satisfying the primary aspects of global sustainable development (Agusti-Juan et al., 2017; Brejnrod et al., 2017; Ding, 2014; Lu et al., 2017; Margarido, 2015; Maxineasa et al., 2015; Pacheco-Torres et al., 2017; Sathre and Gonzalez-Garcia, 2014; Sinha et al., 2016; Vacek et al., 2017; Yao, 2013; Zhao et al., 2017). An important phase from the life cycle of a structure that has a significant impact over the total environmental footprint of the construction industry is represented by the manufacturing of building materials (Hafliger et al., 2017). At the global scale, it is estimated that compared with other industries, the construction sector is the most substantial consumer of natural resources, a significant volume of which is being used before the operation stages of the built structures (Estrada et al., 2012). Of the total environmental footprint of a construction, only 8%e20% results from the materials’ production stage (the pre-operation phase of a structure), thus, it can be considered that the negative effects of building materials do not represent the industry’s biggest ecological problem (Hays and Cocke, 2009; Huberman and Pearlmutter, 2008; Ortiz et al., 2009, 2010). Nevertheless, if we take into consideration the fact that in the near future the environmental impact of the operating stage of a building is expected to signifi- cantly decrease due to the development of new carbon neutral operations systems (Estrada et al., 2012), the choice of materials should be regarded as an important element in reducing the effects of the built environment over the natural one.