Monitoring and thermal performance evaluation of two building envelope solutions in an apartment building

A bio-based multi-layer building envelope assembly has been developed for its integration in newly built and retrofitted buildings. Forest-based materials and biocomposite profiles are used as an alternative to fossil-based insulants and metallic framing, providing a well-insulated and low-thermal-bridge technical solution. The wall assembly has been installed as the external envelope of one apartment of a housing block in Donostia-San Sebastián (Basque Country, Spain). A comparative study has been performed for the bio-based wall and the reference wall of the building. Their in-situ thermal resistance has been obtained by means of three different methods: (1) the steady-state average method, (2) a semi-dynamic method from heat balance at the internal surface, and (3) a dynamic multiple regression method. Reasonably consistent results have been obtained with the three methods: a discussion is provided on the influence of measuring periods and boundary conditions. Outputs from this experimental campaign are valuable as a counterpoint to desktop studies and tests under controlled laboratory conditions. Learnings and outputs from the present study should contribute to a better understanding of the in-situ performance of building envelope assemblies and their assessment methods

Questioning the effectiveness of technical measures implemented by the Basque bottom otter trawl fleet : Implications under the EU landing obligation

The selective properties of a bottom trawl fitted with a 70 mm diamond mesh codend and a 100 mm top square mesh panel (SMP) for hake (Merluccius merluccius), pouting (Trisopterus luscus and Trisopterus minutus) and red mullet (Mullus surmuletus) were investigated over the period 2011-2013. The experiments were carried out over three separate cruises aboard two commercial Basque bottom otter trawlers in the Bay of Biscay area. "Fall-through" experiments were also undertaken to estimate the potential size selection of 100 mm square mesh for the same species. Results from the "Fall-through" experiments and the at-sea selectivity cruises demonstrated that a 100 mm SMP has the potential to enable undersized and immature individuals to escape through the meshes. However, the selectivity cruises demonstrated that in practice, the SMP was largely ineffective at releasing undersized individuals as only a small fraction of the fish entering the trawl attempted to escape through the SMP during their drift towards the codend. The fraction attempting to escape was quantified by the "SMP contact probability" and was less than 4% for hake and red mullet and less than 15% for pouting. Furthermore, for each species, the release potential for the diamond mesh codend was found to be significantly lower than the length-at-maturity and the legal minimum conservation reference size. On average, the proportions of the total catch of undersized individuals of each species retained by the gear, were 52%, 17% and 45% for hake, pouting and red mullet respectively. Based on our findings, we conclude that the gear currently deployed by the Basque bottom otter trawl fleet operating in the Bay of Biscay is largely ineffective at releasing undersized hake, pouting and red mullet. The introduction of the obligation to land all catches, under the 2013 reform of the EU Common Fisheries policy will create new challenges for the Basque bottom otter trawl fleet and thereby an incentive to improve selectivity to avoid unwanted catches of undersized individuals

Estimation of thermal resistance and capacitance of a concrete wall from in situ measurements: A comparison of steady-state and dynamic models

There is a growing interest in characterising the thermal performance of building envelopes when exposed to realistic weather and indoor conditions. In this study, data from a full-scale test of four uninsulated concrete panels is analysed using (1) a steady-state model as per the standard average method, (2) a dynamic lumped resistance-capacitance model with a stochastic method, and (3) a dynamic distributed capacitance model based on an analytical solution. These have been favoured over purely data-driven methods, since their physical formulation allows the characterisation of thermal capacity alongside the usual thermal resistance. The models are applied to different data subsets, sampling times and campaign lengths. For the sole estimation of thermal resistance, winter conditions with constant indoor heating allow campaign lengths around 72 h. For a strong indoor-outdoor temperature difference (e.g. 10 degrees C) steady-state models provide reliable estimates, and lumped capacitance models are found to suit lower temperature differences or less stable conditions. However, for estimating thermal capacity, fluctuating indoor and outdoor temperatures are preferred and only the distributed capacitance model provides consistent estimates for different time steps and data subsets. The present work might be helpful in establishing future guidelines for the use of dynamic methods with physical interpretation, presenting a case study of a simple well-known wall facing a variety of winter and summer conditions. It might also provide a basis for further research, extending the application of these models to more complex multi-layer walls and/or for the assessment of design scenarios including thermal insulation

An Optimization Procedure for the Friction Stir Welding FEM Model of Corner Fillet Joints

Friction stir welding (FSW) is an energy efficient and environmentally "friendly" (no fumes, noise, or sparks) welding process, during which the sheets are welded together in a solid-state joining process. FSW is mature for simple configurations but a significant lack of knowledge is found when dealing with different designs such as T-sections, box sections and corner welds. Although the latter joint morphology has traditionally been considered unfeasible for the process, it seems to have a great potential to be used also for T-joint configurations, a recurrent design pattern in transport applications. A specific tool has been developed and a set of experimental welds has been produced with it. In this paper, experimentally measured and numerically calculated thermal histories were compared and a response surface approach was applied in order to model the behavior of the error functions taken into account. Once the conflicting trend of the selected indicators was observed, a constrained minimization approach was developed. The numerical results, obtained utilizing the numerical parameters from the optimization procedure, showed a very good matching with the experimental evidence. According to the obtained results, the proposed model is able to represent a useful design tool for the process