Hygrothermal performance of historic massive wall: when is 2D simulation necessary?

Hygrothermal analysis of historical building envelopes is crucial in ensuring their durability and enhancing their performances. The use of hygrothermal dynamic simulation is the most effective approach to predict moisture related damages or risk of mould growth on ancient masonry envelopes. However, simulating the hygrothermal behaviour of a historic wall composed by stones or bricks and mortar joints, with a detailed two-dimensional (2D) model, is typically a complex and time-consuming process. For this reason, in numerical models, composite walls are often simplified with a one-dimensional (1D) layer, neglecting the mortar joints. An oversimplified numerical model could affect the evaluation of a retrofit intervention and lead to inadequate design choices. This study evaluates when the description of a historic wall as a 1D homogenous layer leads to an acceptable level of accuracy and when it is necessary the use of a more precise 2D model. We quantified the error by comparing 1D and 2D simulations of different massive walls in three Italian climate conditions. We examined a possible retrofit intervention with different internal insulation systems considering vapor tight, vapor retardant and capillary active solutions. Although simplified 1D models are reliable for thermal parameters, we have identified a different behavior regarding the hygric parameters. Whereas for a capillary active insulation system the 1D and 2D simulations show a reasonable agreement, the 1D approximation is no longer acceptable in the case of vapour closed insulation systems as it leads to large deviations. Knowing when it is possible to implement a simplified 1D model and quantifying the introduced error will support architects and energy consultants in the design process. It will guide them in the choice of the most suitable model depending on their specific requirements

Applied Research of the Hygrothermal Behaviour of an Internally Insulated Historic Wall without Vapour Barrier: In Situ Measurements and Dynamic Simulations

The hygrothermal behaviour of an internally insulated historic wall is still hard to predict, mainly because the physical characteristics of the materials composing the historic wall are unknown. In this study, the hygrothermal assessment of an internally thermal insulated masonry wall of an historic palace located in Ferrara, in Italy, is shown. In situ non-destructive monitoring method is combined with a hygrothermal simulation tool, aiming to better analyse and discuss future refurbishment scenarios. In this context, the original U-value of the wall (not refurbished) is decreased from 1.44 W/m2K to 0.26 W/m2K (10 cm stone wool). Under the site specific conditions of this wall, not reached by the sun or rain, it was verified that even in the absence of vapour barrier, no frost damage is likely to occur and the condensation risk is very limited. Authors proposed further discussion based on simulation. The results showed that the introduction of a second gypsum board to the studied technology compensated such absence, while the reduction of the insulation material thickness provides a reduction of RH peaks in the interstitial area by 1%; this second solution proved to be more efficient, providing a 3% RH reduction and the avoidance of further thermal losses

Applied Research of the Hygrothermal Behaviour of an Internally Insulated Historic Wall without Vapour Barrier: In Situ Measurements and Dynamic Simulations

The hygrothermal behaviour of an internally insulated historic wall is still hard to predict, mainly because the physical characteristics of the materials composing the historic wall are unknown. In this study, the hygrothermal assessment of an internally thermal insulated masonry wall of an historic palace located in Ferrara, in Italy, is shown. In situ non-destructive monitoring method is combined with a hygrothermal simulation tool, aiming to better analyse and discuss future refurbishment scenarios. In this context, the original U-value of the wall (not refurbished) is decreased from 1.44 W/m2K to 0.26 W/m2K (10 cm stone wool). Under the site specific conditions of this wall, not reached by the sun or rain, it was verified that even in the absence of vapour barrier, no frost damage is likely to occur and the condensation risk is very limited. Authors proposed further discussion based on simulation. The results showed that the introduction of a second gypsum board to the studied technology compensated such absence, while the reduction of the insulation material thickness provides a reduction of RH peaks in the interstitial area by 1%; this second solution proved to be more efficient, providing a 3% RH reduction and the avoidance of further thermal losses

Characterization and thermal performance evaluation of infrared reflective coatings compatible with historic buildings

Two infrared reflective coatings recently developed as part of the EFFESUS European research project are characterized and evaluated in this paper. Thermal performance, durability, compatibility with historic fabric, and reversibility are all analysed. The results of extensive research that include laboratory analysis of selected substrates, measurements on a large-scale traditional masonry mock-up, thermodynamic simulations, and finally application in to a real historic building in Istanbul, all support the potential of the new coatings to improve the thermal performance of historic buildings, in keeping with their visual integrity and cultural value. Besides their reflective properties, proven by the thermal stress reductions on the treated surfaces, the new coatings are characterized by low visual impact, easy application, material compatibility, and reversibility after application, as well as durability over time.The EFFESUS project has received funding from the European Union Seventh Framework Programme for research, technological development and demonstration under grant agreement No. 314678. The authors are grateful to Arianna Vivarelli for her contribution to the activities of the project

Mucosal-associated invariant T cells augment immunopathology and gastritis in chronic helicobacter pyloriInfection

Mucosal-associated invariant T (MAIT) cells produce inflammatory cytokines and cytotoxic granzymes in response to by-products of microbial riboflavin synthesis. Although MAIT cells are protective against some pathogens, we reasoned that they might contribute to pathology in chronic bacterial infection. We observed MAIT cells in proximity to Helicobacter pylori bacteria in human gastric tissue, and so, using MR1-tetramers, we examined whether MAIT cells contribute to chronic gastritis in a mouse H. pylori SS1 infection model. Following infection, MAIT cells accumulated to high numbers in the gastric mucosa of wild-type C57BL/6 mice, and this was even more pronounced in MAIT TCR transgenic mice or in C57BL/6 mice where MAIT cells were preprimed by Ag exposure or prior infection. Gastric MAIT cells possessed an effector memory Tc1/Tc17 phenotype, and were associated with accelerated gastritis characterized by augmented recruitment of neutrophils, macrophages, dendritic cells, eosinophils, and non-MAIT T cells and by marked gastric atrophy. Similarly treated MR1−/− mice, which lack MAIT cells, showed significantly less gastric pathology. Thus, we demonstrate the pathogenic potential of MAIT cells in Helicobacter-associated immunopathology, with implications for other chronic bacterial infections

Francisella tularensis induces Th1 like MAIT cells conferring protection against systemic and local infection

Mucosal-associated Invariant T (MAIT) cells are recognized for their antibacterial functions. The protective capacity of MAIT cells has been demonstrated in murine models of local infection, including in the lungs. Here we show that during systemic infection of mice with Francisella tularensis live vaccine strain results in evident MAIT cell expansion in the liver, lungs, kidney and spleen and peripheral blood. The responding MAIT cells manifest a polarised Th1-like MAIT-1 phenotype, including transcription factor and cytokine profile, and confer a critical role in controlling bacterial load. Post resolution of the primary infection, the expanded MAIT cells form stable memory-like MAIT-1 cell populations, suggesting a basis for vaccination. Indeed, a systemic vaccination with synthetic antigen 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil in combination with CpG adjuvant similarly boosts MAIT cells, and results in enhanced protection against both systemic and local infections with different bacteria. Our study highlights the potential utility of targeting MAIT cells to combat a range of bacterial pathogens

Drugs and drug-like molecules can modulate the function of mucosal-associated invariant T cells

The major-histocompatibility-complex-(MHC)-class-I-related molecule MR1 can present activating and non-activating vitamin-B-based ligands to mucosal-associated invariant T cells (MAIT cells). Whether MR1 binds other ligands is unknown. Here we identified a range of small organic molecules, drugs, drug metabolites and drug-like molecules, including salicylates and diclofenac, as MR1-binding ligands. Some of these ligands inhibited MAIT cells ex vivo and in vivo, while others, including diclofenac metabolites, were agonists. Crystal structures of a T cell antigen receptor (TCR) from a MAIT cell in complex with MR1 bound to the non-stimulatory and stimulatory compounds showed distinct ligand orientations and contacts within MR1, which highlighted the versatility of the MR1 binding pocket. The findings demonstrated that MR1 was able to capture chemically diverse structures, spanning mono- and bicyclic compounds, that either inhibited or activated MAIT cells. This indicated that drugs and drug-like molecules can modulate MAIT cell function in mammals

Energy Efficiency Solutions for Historic Buildings. A Handbook

This handbook holistically summarises the principles for the energy retrofitting of historic buildings, from the first diagnosis to the adequately designed intervention: preservation of the historic structure, user comfort, and energy efficiency. The content was developed by an interdisciplinary team of researchers. The wide range of different expertise, design examples, calculations, and measuring results from eight case studies makes this manual an indispensable tool for all architects, engineers, and energy consultants

The “Cost Optimality” approach for the internal insulation of historic buildings

The Directive 2010/31 UE (EBPD) introduces the “Nearly Zero Energy Buildings” linked to cost optimality, where energy benefits are related to economic benefits. The “Cost Optimality” methodology is applicable both to new and existing buildings, as introduced in the Regulation 244/2012. This methodology has been largely applied to existing building, but the literature on historic buildings lacks. However, given the potential of energy retrofit of this kind of buildings, it would be appropriate to develop a specific methodology for the economic valorization of the heritage, considering also the conservation and the historic value of the patrimony. In fact, on the one hand this methodology could be useful for the “energy valorization” of a historic building in relation to the minimum requirements of European and national legislations and budgets. However, on the other hand, we noted the absence of shared information at national level and examples of the “historic reference buildings”. For this reason, case studies on historic buildings become an important starting point to create common typological and repeatable models for applying this methodology. This research aims at evaluating the economic benefits of energy retrofit of a traditional historic masonry, using the “Cost Optimality” methodology. This method is structured into the following parts: (i) definition of the type of masonry; (ii) selection of the insulation systems; (iii) assessment of the energy benefits related to the insertion of various insulation materials; (iv) evaluation of the Life Cycle Costing; (v) evaluation of the optimal insulation performance and cost-effectiveness; and (vi) comparison of energy consumption and Life Cycle Cost to define the most appropriate interventions for the historic wall