Historic, listed, or unlisted, buildings account for 30% of the European building stock. Since they are complex systems of cultural, architectural, and identity value, they need particular attention to ensure that they are preserved, used, and managed over time in a sustainable way. This implies a demand for retrofit solutions able to improve indoor thermal conditions while reducing the use of energy sources and preserving the heritage significance. Often, however, the choice and implementation of retrofit solutions in historic buildings is limited by socio-technical barriers (regulations, lack of knowledge on the hygrothermal behaviour of built heritage, economic viability, etc.). This paper presents the approach devised in the IEA-SHC Task 59 project (Renovating Historic Buildings Towards Zero Energy) to support decision makers in selecting retrofit solutions, in accordance with the provision of the EN 16883:2017 standard. In particular, the method followed by the project partners to gather and assess compatible solutions for historic buildings retrofitting is presented. It focuses on best practices for walls, windows, HVAC systems, and solar technologies. This work demonstrates that well-balanced retrofit solutions can exist and can be evaluated case-by-case through detailed assessment criteria. As a main result, the paper encourages decision makers to opt for tailored energy retrofit to solve the conflict between conservation and energy performance requirements.

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A rormd robin test programme was executed amongst several laboratories on the beam test recommended by the RILEM TC 162-TDF [1]. In the proposed test method, the mid-span deflection is to be measured on both sides of the beam (referred to as 81 and 62). A systematic fibre counting exercise was carried out on several beam sPecimens to investigate whether there is a correlation between differences between 8~ and 6z and the fibre distribution. The findings of the investigation suggest that differences between 8~ and 8z are not strongly linked with the fibre distribution regardless of concrete strength. It is likely that this phenomenon arises because the supports and loading points have enough degrees of freedom to accommodate any unevenness on the specimen surface. This reflects well on the robustness of the proposed test method as it means that the proposed boundary conditions are able to adapt and tolerate (to a certain degree) surface non-unifbrmity. However, it is also suggested that significant dift~ences between ~ and 82 may be brought about by experimental errors. The fibre count also reveals that toughness increases with the number of fibres across the critical section.1359-5997/03 9 RILEM

A round robin test programme was carried out on the beam-bending test recommended by the RILEM TC 162-TDF [1 ]. Plain concrete and steel fibre reinfbrced concrete (SFRC) beams were included in the test programme. The material variables for the SFRC beams consisted of two concrete strengths, three fibre dosages and three types of fibres. A comprehensive statistical analysis was carried out to determine the applicability and robustness of the test method. It was tbund that although inter-lab variations do occur, this was relatively small compared to the inherent material variation. It is also possible that the high variations observed could be due to the relatively small cross sections used for the test beams. Additionally, an investigation was carried out to evaluate the objectiveness of the calculation procedure proposed by RILEM TC 162-TDF to obtain the necessary design parameters. It was found that the prescribed calculation procedure was satisfactory, as the variation between the design parameters calculated at different laboratories was generally within the range of • An alternative method of obtaining the design parameters, by considering residual strengths, is suggested as it simplifies the calculation procedure and the test method. In general, the beam test was found to be a good robust test and relatively easy to carry out.. RESUMsUn programrne d'e.~ais comparatifi" entre laboratoires a dtO rdalisd pour le test de poutre soumise h la flexion, commepreser# par TC 162-TDF de la RILEM. Des poutres en b~ton normal et en b~ton de fibres m~talliqu~s" (BFM) sont inclues dans le programme d'es~i~. Pcatr les poutres en BFM, on a con~Mdrd comrne variables" de mat&'iaux: deux rdsi~tanc~es gl la compression, tro~ dosages" ate fibres et trois (vpes de fibres. Une anaO,se stat~tique exkxtustive a Ot~ erAcmOe l~mr determiner la pertinence c4 Ia solMitd de la m~thode d'essai. On a constatO que, bien que des variations de r~,~ltats entre les laboratoires existent, celles~'i sont relativement petites; surtout lorsque l',on compare avec lea' :mriations intrim~es des mat&iawc eux-m~mes. Ces derni~es variations peuvent ~re ~galement &4es cnec sections trans~ersales relativement petites qui sont utilis.~es pour les essais de poutre. Ensuite, une analyse a ~td rdalisOe en vu d'&,a.hter l'objectbeit~ de la mOthode de calcut q~d est proposd par TC 162-TDF de la R1LE]ff pour obtenir les paramfitres n~cessaires lots du dimemionnement. On a cons, taM que la m~thode de calcul prescrite" dtait satisftisante, parce que la variation des param~tres; calcut~e par les dij]~rents k~oratoires pour le dimensionnement; Otait d'un ordre de grandeur de +_5%. Une mdthode alternatfi~ est ndanmoins proposOe pout" obtenir les para,'n~es de" dimem'ionnement en prenant en comid~ration la r~sistance rds'iduelle. Cette m~thode sinwlifie la mdttuMe de cak~l et la m~thode d'essai. En gOndral, l ' essai de poutre soumise h la flexion simple, comme pre~crit par le TC 162-TDF de la RILE?r est un essai robuste et relativement simple ?t exdcuter. 1359-5997/03 ...

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Buildings of heritage significance due to their historical, architectural, or cultural value, here called historic buildings, constitute a large proportion of the building stock in many countries around the world. Improving the performance of such buildings is necessary to lower the carbon emissions of the stock, which generates around 40% of the overall emissions worldwide. In historic buildings, it is estimated that heat loss through external walls contributes significantly to the overall energy consumption, and is associated with poor thermal comfort and indoor air quality. Measures to improve the performance of walls of historic buildings require a balance between energy performance, indoor environmental quality, heritage significance, and technical compatibility. Appropriate wall measures are available, but the correct selection and implementation require an integrated process throughout assessment (planning), design, construction, and use. Despite the available knowledge, decision-makers often have limited access to robust information on tested retrofit measures, hindering the implementation of deep renovation. This paper provides an evidence-based approach on the steps required during assessment, design, and construction, and after retrofitting through a literature review. Moreover, it provides a review of possible measures for wall retrofit within the deep renovation of historic buildings, including their advantages and disadvantages and the required considerations based on context.

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