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Energy retrofitting is performed to reduce the energy demand from existing buildings. Different measures can be implemented; however, older buildings will likely never live up to the demands of new construction. Nevertheless, the potential for energy savings must be pursued. Additional insulation is a retrofitting measure that can reduce heat loss through the building envelope and thereby provide energy savings. Internal insulation is introduced when external insulation, a more robust and moisture-safe measure, is not possible. Besides energy savings, internal insulation can provide increased thermal comfort. However, the indoor climate may suffer from internal insulation, if not designed, installed, and managed properly. Internal insulation increases the risk of moisture accumulation behind the insulation, which increases the risk of mold growth and other degradation processes. The current paper presents a case study of a building complex from 1961, where six adjoining apartments were internally insulated in 2015. The external walls were 360 mm (14.2 in.) thick, consisting of yellow brick (externally) and lightweight clinker concrete (internally). The walls were insulated with 50 mm (2.0 in.) (façades) and 80 mm (3.1 in.) (gable) insulation with a semi-diffusion tight and supposedly capillary active system, while the wall in the stairwell (north) was insulated with 50 mm (2.0 in.) of diffusion open and capillary active calcium silicate. For 6 years, the hygrothermal conditions were monitored in the interface between wall and internal insulation, where there is high risk of moisture accumulation. Measurements were performed in both northern (façade), southern (façade), and western (gable) orientations. The paper presents methods used, results from the in-situ measurements, and analysis hereof. The results show acceptable hygrothermal conditions at the interfaces and very little risk of mold growth. Furthermore, 6-12 months after applying internal insulation, the built-in moisture was dried out. Energy retrofitting is performed to reduce the energy demand from existing buildings. Different measures can be implemented; however, older buildings will likely never live up to the demands of new construction. Nevertheless, the potential for energy savings must be pursued. Additional insulation is a retrofitting measure that can reduce heat loss through the building envelope and thereby provide energy savings. Internal insulation is introduced when external insulation, a more robust and moisture-safe measure, is not possible. Besides energy savings, internal insulation can provide increased thermal comfort. However, the indoor climate may suffer from internal insulation, if not designed, installed, and managed properly. Internal insulation increases the risk of moisture accumulation behind the insulation, which increases the risk of mold growth and other degradation processes. The current paper presents a case study of a building complex from 1961, where six adjoining apartments were internally insulated in 2015. The external walls were 360 mm (14.2 in.) thick, consisting of yellow brick (externally) and lightweight clinker concrete (internally). The walls were insulated with 50 mm (2.0 in.) (façades) and 80 mm (3.1 in.) (gable) insulation with a semi-diffusion tight and supposedly capillary active system, while the wall in the stairwell (north) was insulated with 50 mm (2.0 in.) of diffusion open and capillary active calcium silicate. For 6 years, the hygrothermal conditions were monitored in the interface between wall and internal insulation, where there is high risk of moisture accumulation. Measurements were performed in both northern (façade), southern (façade), and western (gable) orientations. The paper presents methods used, results from the in-situ measurements, and analysis hereof. The results show acceptable hygrothermal conditions at the interfaces and very little risk of mold growth. Furthermore, 6-12 months after applying internal insulation, the built-in moisture was dried out.

This report is one of five deliverables related to WP6 ‘Development and evaluation of guidelines and web-based preliminary assessment tool‘. The prime objective of WP6 is to develop and to assess written and web-based guidelines and a web tool (including a feasibility study of possible input and output data) for renovation of historic buildings with internal insulation. This deliverable contains the written guidelines, referring to Task 6.1, consisting of a guideline for setting the goal of applying internal insulation (Section 3), a guideline for deciding whether a building is suitable for internal insulation (Section 4), a guideline for selecting an internal insulation system (Section 5) and a guideline for evaluating the energy saving potential and the environmental impact (Section6). The written guidelines are also made accessible through a web-site, described in deliverable D6.3.

This report is one of five deliverables related to WP6 ‘Development and evaluation of guidelines and web-based preliminary assessment tool‘. The prime objective of WP6 is to develop and to assess written and web-based guidelines and a web tool (including a feasibility study of possible input and output data) for renovation of historic buildings with internal insulation. This deliverable contains the written guidelines, referring to Task 6.1, consisting of a guideline for setting the goal of applying internal insulation (Section 3), a guideline for deciding whether a building is suitable for internal insulation (Section 4), a guideline for selecting an internal insulation system (Section 5) and a guideline for evaluating the energy saving potential and the environmental impact (Section 6). The written guidelines are also made accessible through a web-site, described in deliverable D6.3.

In historic masonry buildings, wood can be embedded in the walls as storey partition beams, or as supportive wall plates. Half-timbered masonry constructions, or wooden frames, e.g. combined with internal insulation, are other examples of wooden elements. Wood decaying fungi can cause serious damage to wood, which may lose mass and strength, ultimately yielding the risk of collapse. In addition, some fungal species may even be hazardous for occupants. All wood decaying fungi depend on favorable moisture and temperature conditions, although the threshold conditions may vary with various fungal species and types, and state of the wood. To predict the risk of occurrence of wood rot, several models have been developed, however most of these are based on a limited number of experiments, or very specific cases. For these reasons, the applicability of the models to other scenarios (fungal species, wood species) may not be appropriate. Furthermore, another failure mode for wood and moisture, is mold growth, which is initiated at lower moisture levels. An indication of risk of mold growth would indicate problems or risks before the initiation of wood rot. Mold growth does not deteriorate the wood, but is usually equally undesired due to health concerns of occupants. For this reason, there might be places where some mold growth would be acceptable, e.g. embedded beam ends if there is no transfer of air from the moldy area to the indoor air. Therefore, risk of rot could be important. The paper investigates models for mass loss due to wood decay and mold growth based on exposure time to favorable hygrothermal conditions. The investigation is based on inspection of wood samples (wall plates) from a full-scale experimental setup of masonry with embedded wood and monitored conditions, to which the prediction models will be applied. Monitored hygrothermal conditions were implemented in mold and wood decay models, and samples were removed from the test setup. The implemented models yielded high mold index and mass loss, whereas neither mold nor decay was observed in the physical samples. Results indicate that the implemented models, in these cases appear to overestimate the risks of mold and rot in the supportive lath behind the insulation.

Historical buildings represent cultural, historic and aesthetic value, whether preservation worthy or not. For this reason, the concept of internal insulation has been introduced as a possible energy retrofitting measure for such buildings. The application of the thermal insulation on the interior side of the wall reduces the heating energy consumption and improves the thermal comfort. But it also changes the hygrothermal conditions of that wall reducing the drying potential and leaving the original wall colder and damper when compared to pre-retrofitting. This may lead to undesired consequences like interstitial condensation, mold growth, wood rot and the general deterioration of the façade materials and components. The prediction of the hygrothermal performance of internal insulation solutions plays therefore an important role when designing successful retrofit measures. External loads, e.g. wind driven rain (WDR) and solar radiation, may vary largely depending the location and orientation and have a significant impact especially on historic buildings with porous masonry walls. This paper presents a simulation study for assessment of the hygrothermal performance of internally insulated historic masonryunder given conditions. A monitored case study made up the basis for this study that primarily focuses on the influence of orientation, indoor climate, façade color and brick type with regard to WDR, investigated through dynamic hygrothermal simulations. The results show that high loads from WDR inevitably increased the moisture content of the wall, but also certain material parameters and orientation, including solar radiation in combination with WDR play a role. Historical buildings represent cultural, historic and aesthetic value, whether preservation worthy or not. For this reason, the concept of internal insulation has been introduced as a possible energy retrofitting measure for such buildings. The application of the thermal insulation on the interior side of the wall reduces the heating energy consumption and improves the thermal comfort. But it also changes the hygrothermal conditions of that wall reducing the drying potential and leaving the original wall colder and damper when compared to pre-retrofitting. This may lead to undesired consequences like interstitial condensation, mold growth, wood rot and the general deterioration of the façade materials and components. The prediction of the hygrothermal performance of internal insulation solutions plays therefore an important role when designing successful retrofit measures. External loads, e.g. wind driven rain (WDR) and solar radiation, may vary largely depending the location and orientation and have a significant impact especially on historic buildings with porous masonry walls. This paper presents a simulation study for assessment of the hygrothermal performance of internally insulated historic masonryunder given conditions. A monitored case study made up the basis for this study that primarily focuses on the influence of orientation, indoor climate, façade color and brick type with regard to WDR, investigated through dynamic hygrothermal simulations. The results show that high loads from WDR inevitably increased the moisture content of the wall, but also certain material parameters and orientation, including solar radiation in combination with WDR play a role.

This report comprises a study of material threshold values, failure modes and related failure prediction models to enable an evaluation of adding internal insulation in historic brick buildings. Threshold values and prediction models have been investigated both within literature and through laboratory study, by for instance comparing prediction models to real field results and by testing threshold values in laboratory. The aim of this report is to find threshold values and suitable and reliable prediction models to be included in the decision guidelines and the web tool, which are the final outcomes of the RIBuild project. Failure modes included in the report are mould growth on building materials, rot and wood decay, frost damage and discoloration of facades. This report comprises a study of material threshold values, failure modes and related failure prediction models to enable an evaluation of adding internal insulation in historic brick buildings. Threshold values and prediction models have been investigated both within literature and through laboratory study, by for instance comparing prediction models to real field results and by testing threshold values in laboratory. The aim of this report is to find threshold values and suitable and reliable prediction models to be included in the decision guidelines and the web tool, which are the final outcomes of the RIBuild project. Failure modes included in the report are mould growth on building materials, rot and wood decay, frost damage and discoloration of facades.

This report comprises a study of material threshold values, failure modes and related failureprediction models to enable an evaluation of adding internal insulation in historic brick buildings.Threshold values and prediction models have been investigated both within literature and throughlaboratory study, by for instance comparing prediction models to real field results and by testingthreshold values in laboratory. The aim of this report is to find threshold values and suitable andreliable prediction models to be included in the decision guidelines and the web tool, which are thefinal outcomes of the RIBuild project. Failure modes included in the report are mould growth onbuilding materials, rot and wood decay, frost damage and discoloration of facades.