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This article depicts the effect of carding and pressing on hygrothermal properties of hemp fibers nonwoven mats, trying to understand if their implementation can improve their behavior when employed as insulation materials in buildings. Hemp fibers belonging to Cannabis Sativa species and coming from local area (Apulia - Italy) were examined, then samples of carded and pressed hemp fibers nonwoven mats were prepared. According to European standards, the thermal conductivity, the vapor permeability and the fire reaction of hemp fibers samples were measured. Results were compared to each other and with those of a commercial nonwoven mat made with hemp (90 wt. %) and synthetic fibers (10 wt. %), used as reference. We observed that carded and pressed hemp fibers were characterized by a lower thermal conductivity when compared to unprocessed hemp fibers, likely because the removing of wood elements. On the other hand, not processed hemp fibers show higher breathability when compared to carded and pressed ones, as well as with respect to the commercial nonwoven mat. Moreover, it was proved that the absence of synthetic commingled fibers in hemp fibers allows a better behavior in fire reaction. At last, the improvement in terms of insulation properties of a hollow brick when filled with hemp fibers was verified, by comparing the thermal conductivities of an empty and a filled hollow brick; as expected, the filled hollow brick shows a lower thermal conductivity, underlining the effectiveness of hemp fibers as insulation material.

Mediterranean deep retrofit markets are characterized by common barriers and bottlenecks, which barely have been identified as shared challenges, and this has led to a lack of dedicated solutions and to a substantial delay in achieving the 2020 EU policy targets. This situation is addressed by the H2020 HAPPEN project by proposing a new MedZEB approach characterized by the following features: Holistic, i.e., aimed at integrating the most relevant aspects of the retrofitting supply chain; Transparent, i.e., aimed at putting on the market novel tools for enhancing investors’ trust; Adaptive, i.e., aimed at enhancing “added values” of the retrofitting such as flexibility, well-being, etc. Having arrived at its midpoint, HAPPEN has produced an advanced version of its main outputs, among which are: the HAPPEN cost-optimal technical solutions, developed according to a step-by-step logic; the HAPPEN financial solution, fully integrated with the step-by-step logic, and aimed at funding the retrofitting process by relying on the energy savings achieved; the MedZEB protocol conceived as a guarantee scheme for the achievement of retrofit targets; the HAPPEN platform, an assisted digital marketplace aimed at matching demand and offer according to a one-stop-shop logic, at defragmenting the retrofit value chain, and at supporting actors with dedicated tools. These outputs have been developed also thanks to an extensive living laboratory and pilot-building program, carried out within ten pilot sites across seven EU Med countries; this has made it possible for a large engagement of potential users, which resulted in the ideation of the HAPPEN program, an overall framework aimed at integrating project outputs into an exploitable renovation procedure powered by the HAPPEN platform. This paper describes the first simulation of such a procedure in its entirety based on a real case study. After characterizing the building according to the HAPPEN reference buildings and climates lists, a step-by-step cost-optimal package of solutions was calculated, followed by the application of the HAPPEN financial solution, and by the draft issue of the MedZEB protocol. Results provide the first evidence of the effectiveness of the MedZEB approach in potentially unlocking the deep retrofit market in the Med area, with special attention to the possibility of funding the interventions by relying on the economies generated by the energy savings achieved. Further, the project activities will be aimed at co-creating, together with relevant stakeholders, a go-to-market strategy for the HAPPEN program.

This paper presents the results of the lab-scale thermophysical characterization of materials for the next generation of solar receivers employed in CSP plants. The receiver material plays a crucial role in absorbing sunlight, minimising heat losses and transferring heat to the working fluid. Therefore, new receivers should be mechanically tough and highly thermally conductive. Porous SiC and SiSiC were the two industrial grade solutions investigated for this purpose. The Laser Flash Method was employed to analyse the transient thermal behaviour of the materials. The results of the measurements in terms of thermal diffusivity, specific heat and thermal conductivity are provided and compared with the literature data available.

The thermal and mechanical properties of a lightweight alkali bonded material were investigated in correlation with the microstructure and porosity. The material was produced using fine granules of expanded perlite as raw powder and potassium di-silicate aqueous solution as alkaline activator, instead of the commonly used sodium silicate, to improve thermal performances. After consolidation, the material was subjected to microstructural analyses, as well as to thermo-physical and mechanical tests. Density was 467 ± 40 kg·m−3, the total porosity 80 vol%, the average pore size 0.2 µm and compressive strength was 1.5 ± 0.5 MPa. It was observed that, besides the action of potassium di-silicate as an alkali binder, expanded perlite granules reacted on the surface forming geopolymer nano-precipitates. Laser Flash Method was employed to evaluate the whole thermal behavior within the temperature range 25–550 °C: thermal conductivity was 0.084 m−1K−1 at 25 °C and 0.121 W·m−1K−1 at 550 °C. At high temperature, the thermal conductivity resulted similar or even lower when compared with commercial perlite – sodium silicate materials with lower densities in the range 180–260 kg/m3. Results show that lightweight alkali bonded expanded perlite materials can be produced with improved thermal properties by exploiting potassium silicate and overcoming the poor temperature resistance of organic binders.

The transient behaviour of a micro thermoelectric cooler is described in the present paper through the theory of the thermal wave, involving the relaxation time. The internal heat generation due to the sudden application of the electric current is taken into account by means of the Heaviside function. The governing equations of both the semiconductors are solved by a modified Separation of Variables Method that allows us to have a better description of the device which can be obtained at early times. As regards the performances, the cooling load shows discontinuities due to the contributions of the travelling wave fronts of both the semiconductors. The results show that the coefficient of performance (COP) of the device obtained with the hyperbolic model is lower than that provided by the parabolic model at early times.