Wood is an orthotropic material used since ancient time. A literature research about the mechanical properties of density, fracture toughness, modulus of elasticity, and Poisson’s ratio has been done to have a broader view on the subject. The publications relating to the topic were found through the two search engines Scopus and Google Scholar that have yielded several papers, including articles and book sections. In general, there is no standardization on the method of analysis carried out on wood, underlining the great difficulty in studying this complex material. The parameter of density has a great variability and needs a deeper investigation; fracture toughness is not always available in literature, not even in the different directions of the wood sample. Interesting is the modulus of elasticity, which provides a correlation with density, especially in longitudinal section but, again, it needs to be studied in detail. The parameter of Poisson’s ratio is provided as single values in three different directions, but mainly for softwood. All the parameters require a more in-depth study for both softwood and hardwood. Furthermore, the type of analysis, whether experimental or modelling, needs to be standardized to have more comparable results.
Under constant temperature conditions, air relative humidity variations affect hygroscopic objects, such as wood, modifying their moisture content and provoking, at low values, damages and fractures. The parameters (amplitude, counts, and energy) derived from the acoustic emission non-destructive technique are calibrated with respect to equilibrium moisture content values using 14 samplings of Pinus sylvestris. The experimental procedure uses multi-technique approaches involving a universal testing machine, digital image correlation, and acoustic emissions, and notes that the three parameters of acoustic emission strictly depend on the equilibrium moisture content. For a better interpretation, a statistical approach is applied to model the equilibrium moisture content variations radially and longitudinally. Amplitude, counts, and energy are calibrated as a function of the equilibrium moisture content, indicating that all three parameters are necessary to have an integral vision of the conservation of a wooden material. Moreover, the shape of the macro-fractures that occur at the surface can be associated with the level of moisture or dryness of the sample. Finally, the proposed method can be used in situ because, through acoustic emission monitoring, it is possible to quantify the fingerprint of the state of conservation of a material.
Portugal, Italy, and Norway differ by energy performance of buildings and gross domestic product (GDP). Portugal has significantly highest thermal discomfort with harsher winters. In 2021, 80% of Portuguese buildings had a low energy rating, with 75% of buildings without thermal insulation, highly contributing to the energy poverty (EP) of the country. In Italy, despite a generally mild climate, the building stock has low thermal performance. The most affected areas are the suburban and peri-urban ones, with an EP rate in southern regions between 13% and 20% compared to 8.8% at national level. Moreover, 65% of buildings were constructed before the first law on energy saving criteria and a 25% of it has never undergone any work of maintenance or improvement. Norway, despite the limited studies performs well respect to other European Economic Area and European Union countries, in investing and using indicators to enhance and monitor the green energies’ use. Because of energy price growth, seasonal price fluctuations, and different energy tariffs, energy inequality is increasing. EP risk is underestimated, masked by Norway’s high GDP and regional price disparity. Energy inequality is increasing due to energy price growth, seasonal price fluctuations, and energy prices’ geographical inequality. The barriers in reducing EP are the underestimation of risk masked by the high GDP, and the need of homogenized prices in Norway. This study provides an overview to discuss EP awareness and it assesses the drivers and barriers that influence building’s energy efficiency renovation.
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