ZEMCH 2015 - International Conference Proceedings | Page 586

Introduction
The introduction of new standards for the levels of indoor comfort required the adaptation of existing buildings . These , in most cases , do not satisfy the required value of thermal transmittance . This has resulted in the development of new strategies for the adaptation of the building envelope , beginning in northern Europe and concerned the adjustment of the energy performance in the case of cold climates . Later on , also for Mediterranean areas , and then in the case of hot climates it became an important strategy to introduce thermal insulation systems for the building envelope . The need to improve the thermal insulation of the building envelope determine a growth of the industrial field based on the production of insulating materials of different origins , for example , the cheaper , but less sustainable , are the synthetic ones . At the same time , it has developed the production of eco-friendly insulating materials . This new materials field could contribute , as well as the use of renewable resources of energy , also to economic development in those countries where , at the present time , these resources are found in abundance but they and are not well used .
The energy retrofit
The energy retrofit consists of all the actions aimed to renovate the existing buildings stock , by adapting their performances to the ones required by current laws . To act on existing buildings means the possibility to choose between different strategies , each that cannot however dispense with proper thermal insulation of the building envelope , the main regulator of the heat exchange between external and internal environment . Among the most common retrofits we can find the following ones :
• Insulation of the building envelope ;
• thermal inertia increasing ;
• replacement of windows with innovative systems ;
• introduction of solar shading devices ;
• replacement of air-conditioning systems ;
• replacement of lighting systems ;
• use of natural sources of thermal energy ;
• introduction of renewable energy . Among the systems above , there are methods of intervention that allow to work directly on the building structure increasing its thermal performance , by reducing therefore the use of mechanical systems of air-conditioning . These passive actions , provide above all initials contained expenses , easily amortizable over the short term , thanks to the considerable reduction in energy bills due to their implementation . In recent years , the research and experimentation on the building envelope have spread different kind of materials and technologies , ever more efficient , able to significantly increase the energy efficiency . To insulate the opaque envelope , in fact , allows to contain the main heat losses and to ensure adequate levels of interior comfort for extended periods of time . The choice between the insulating materials changes depending on the case , not only relating to the level of thermal conductivity of each panel , but also to the geographical context and , therefore , the needs which must be meet . Furthermore , such a choice implies that the requirements ever more restrictive than the law now imposes in each climate zone ( Italian Law no . 10 of 1991 “ Regulations on the rational energy use ,
584 ZEMCH 2015 | International Conference | Bari - Lecce , Italy