Several recent studies have highlighted the potential of Actively Heated Fiber Optics (AHFO) for high resolution soil moisture mapping. In AHFO, the soil moisture can be calculated from the cumulative temperature (normalTcum), the maximum temperature (normalTmax), or the soil thermal conductivity determined from the cooling phase after heating (λ). This study investigates the performance of the normalTcum, normalTmax and λ methods for different heating strategies, i.e., differences in the duration and input power of the applied heat pulse. The aim is to compare the three approaches and to determine which is best suited to field applications where the power supply is limited. Results show that increasing the input power of the heat pulses makes it easier to differentiate between dry and wet soil conditions, which leads to an improved accuracy. Results suggest that if the power supply is limited, the heating strength is insufficient for the λ method to yield accurate estimates. Generally, the normalTcum and normalTmax methods have similar accuracy. If the input power is limited, increasing the heat pulse duration can improve the accuracy of the AHFO method for both of these techniques. In particular, extending the heating duration can significantly increase the sensitivity of normalTcum to soil moisture. Hence, the normalTcum method is recommended when the input power is limited. Finally, results also show that up to 50% of the cable temperature change during the heat pulse can be attributed to soil background temperature, i.e., soil temperature changed by the net solar radiation. A method is proposed to correct this background temperature change. Without correction, soil moisture information can be completely masked by the background temperature error.

No abstract

Hemp-lime composite is a natural material, which is being increasingly used and studied in the construction sector, thanks to its recyclability, hygrothermal comfort and healthiness features. The aim of this paper is to test the benefits in terms of energy efficiency achieved through the use of hemp-lime composite as insulation in a possible refurbishment intervention. With the aim of extending the knowledge about the benefits achieved through from the integration of this natural material into construction production process, a real building in south of Italy was selected and a substitution of the standard gypsum-lime plaster with a hemp-lime one was simulated by means of a specific software (Termus® by Acca Sotware, Bagnoli Irpino, Italy), serving for the assessment of the energy performance. Case study analysis highlighted the good thermal insulation properties of hemp-based plaster, allowing thermal dispersion to decrease in the winter season and improve the summer performance of the walls by approximately 20% compared to traditional plaster. This results in a one-level improvement of the building in energy classification according to Italian regulation.

No abstract

7Measuring water content in buildings of historical value requires non-invasive techniques to avoid the 8 damage that sample taking or probe insertion may cause to the investigated walls. With this aim, a stepped 9 frequency ground penetrating radar (GPR) system was tested to assess its applicability in moisture 10 measurements of porous masonry elements. The technique was tested on a real scale wall made with yellow 11Neapolitan tuff bricks, a material commonly found in historical buildings of Campania (Southern Italy). First, 12 the antenna was calibrated to find its characteristic transfer functions. Then 64 GPR acquisitions, coupled 13 with gravimetric measurements of the volumetric water content, were performed on the tuff wall in 14 laboratory controlled conditions. A full inverse modelling of the GPR signal on tuff was used to retrieve 15 dielectric permittivity and electrical conductivity of tuff at various water contents. By linking these 16 characteristic electromagnetic parameters to the water content, the calibration relationships specific for 17 yellow Neapolitan tuff are defined, which can be used for moisture measurements by GPR in real case 18 studies. The experimental results lead to a robust identification of clearly defined monotonic relationships 19 for dielectric permittivity and electrical conductivity. These are characterized by high values of the 20 correlation coefficient, indicating that both parameters are potentially good proxies for water content of 21 tuff. The results indicate that GPR represents a promising indirect technique for reliable measurements of 22 water content in tuff walls and, potentially, in other porous building materials. 23