A review of the properties of recycled and waste materials for energy refurbishment of existing buildings towards the requirements of NZEB

In Europe buildings account for 40% to 50% of total energy consumption and the largest greenhouse gases emitters and urgent measures and valid instruments are therefore required to improve energy saving, use of renewable sources in moving towards a sustainable materials management where waste becomes a "resource". In this context, there is an increase in research into development and manufacturing of new eco-friendly building envelope components from recycled and waste materials as high value-added good circular economy practice. Waste management may have significant effects in the sector of sustainable building the ultimate objective being the alternative construction materials replacing traditional materials: the development of innovative techniques aims to incorporate wastes into the production of building materials - for examples rubber, fly ash and sludge, etc. - to enhance thermal insulation properties. An effort in the sustainability in building design process is to develop researches aimed at enhancing thermal performance of components using materials capable of reusing a high waste content. The goal of this paper is to examine the technical feasibility of using inert waste materials from the combustion of municipal solid waste or solid recovered fuel and highlight changes in thermal characteristics (thermal conductivity, specific heat and density) by adding recycled and waste materials to the construction materials. The paper explores the potential of the use of thus obtained materials for the energy-refurbishment of existing buildings or with the challenge of meeting stringent energy consumption limits which are typical of a NZEB (net-zero energy building).