A guidance was developed to find a sustainable balance between energy savings and heritage preservation when retrofitting heritage buildings. It was applied in a study on the retrofitting of typical Alsatian heritage buildings. Seven buildings were analysed before retrofitting to evaluate them on five criteria: energy savings, heritage preservation but also comfort in winter and in summer and moisture damage. Then, compatible retrofitting works on walls, ceilings, floors, front door, windows, ventilation and heating and hot production water systems were selected in order to create three retrofitting scenarios: a high-energy efficiency scenario with moisture-permeable materials, a balance scenario between energy efficiency and heritage preservation and a high heritage preservation scenario. The results of the study showed that these sustainable retrofitting scenarios preserve heritage while saving energy and are available in a web publication headed to Alsatian private individuals. The guidance in itself can be easily replicated to other types of heritage buildings.
Oporto’s traditional buildings are the major contributors for shaping the World Heritage Site Despite this, and as is the case in most European historic cities, they are not individually listed and any adaptations to make them comply with current energy efficiency requirements may cause negative impacts on their authenticity and integrity. This paper aims to identify which energy efficiency improvement measures can be applied without damaging the buildings’ heritage value. For this purpose, fieldwork and simulation data of ten case studies were used. On-site results revealed that the energy consumption in Oporto’s traditional buildings was below European average and the households expressed that their home comfort sensation was overall positive. Simulations showed that introducing insulation and solar thermal panels would be ineffective in terms of energy and cost efficiency as well as comfort improvement. This study reinforces the idea that traditional buildings perform better than expected in terms of energy consumption and can be retrofitted and updated at a low-cost and with passive solutions.
Abstract Environmental sustainability certification represents a strategic opportunity for improving energy efficiency, environmental quality, rational use of resources and design innovation in historic buildings, allowing greater transparency on energy uses and environmental management. To address these aspects, the Green Building Council of Italy has developed a new rating system, GBC Historic Building®, derived from the most diffused environmental sustainability assessment method worldwide (i. e. Leadership in Energy and Environmental Design - LEED®), in order to evaluate the sustainability level of restoration, rehabilitation and adaptation of historic buildings built before the end of World War II. This manuscript focuses on how this innovative assessment method addresses energy issues and indoor environmental quality aspects throughout the different thematic areas, introducing the new category “Historic Value”, distinctive of this protocol, aimed at improving the knowledge on the historic building and to support a sustainable approach in the restoration process.
Abstract This paper is aimed at achieving a better understanding of the original state before the restoration project in 1931 and the current structural state of the great Mosque of Mohamed Ali in citadel Cairo, Egypt. A 3-D finite element model for the whole Mosque was constructed for these purposes. Elastic analysis under static and lateral earthquake loads was conducted to verify the efficiency of the main covering domes restoration project in 1931 and to specify the positions of the critical stresses. The accurate and detailed information that was collected during the restoration project in 1931 concerning the structure of the Mosque was used as database for identifying the geometrical and structural properties of the model. The results provide insight to the structural behavior of the Mosque and the current state of stresses. The study also verifies the main causes for the valuable restoration project in 1931, where the stone domes and semi-domes covering the Mosque were replaced by reinforced concrete one . Also, the places of the Mosque that need more sophisticated analysis could be identified.
Abstract Pigeon droppings are implicated in spoiling and decay of buildings. Several studies have examined the effects and chemistry of accumulations of pigeon droppings under highly localised pigeon roosts. Scant information exists on the impact caused by individual pigeon droppings at perch sites, even though these constitute the majority of bird use in urban areas. This study experimentally examined the processes that affect masonry immediately after pigeon excreta have been voided from the body and what effects discrete, fresh pigeon droppings have on different kinds of sandstone. The experiments demonstrated the susceptibility of freshly deposited excreta to environmental conditions (relative humidity and precipitation). In real-life situations, with pigeon excreta deposited on window ledges, cornices and parapets, the majority of damage would occur within the first two weeks of deposition. After that, the majority of individual droppings would have either dissolved or desiccated to such a degree that they would have rolled off. Much of the observed staining is superficial. While individual bird droppings make a building look dirty, even for months at a time, the effect on the building material is not substantial unless other factors come into play such as colonisation of the excreta by mould or leaching of salts from the excreta.
Abstract An archaeological cellar has been excavated under the Basilica of Our Lady in Tongeren, as part of an extensive restoration and revitalization campaign that started in 1999, Figure 1. The cellar will enable to descend to the early Roman history of the site under and surrounding the basilica. The excavation and construction of the archaeological cellar were finished in 2007. After that the air-conditioning system and the accessibility of the cellar were installed In successive phases. At present, the integration of the archaeological cellar under the basilica with the archaeological field around the basilica is under construction. Building in the large cellar under the complete church without endangering the stability of the building was a complex construction work, as explained further in the paper. The project was realized in successive phases, to enable continuous use of the church for services as well as its accessibility as pilgrimage site. After the construction of the cellar, the focus shifted to the conservation of the archaeological remains in view of the future (touristic) exploitation of the cellar. In view of that, climate control in the cellar is crucial. The foundation footings and walls have been covered underground during centuries, and are now suddenly exposed to an inside environment with higher temperatures and lower humidity. The climate control measures during the construction works are presented, as well as the performance of the final permanent climate control installation. The specific consolidation and conservation works on the foundation masonries are profoundly discussed.
Abstract In 2010 burnt lime blocks were accidentally mixed with limestone concrete aggregates at a Belgian limestone and lime production plant. The contaminated limestone aggregates were used in precast concrete factories. The concrete elements used in several constructions quickly showed pop-outs, caused by swelling of lime nodules. The appearance of pop-outs in suspected constructions was recorded. An extensive experimental program as well as on site observations have been made, to monitor the evolution of the pop-out phenomenon with time. The pop-out evolution in outside exposure conditions is compared to the evolution of pop-outs under inside climatic conditions. Outside, the phenomenon becomes marginal after about 2 years. In inside exposure conditions, the phenomenon still continues after 7 years, be it at a low rate.
AbstractReed (Phragmites australis(Cav.) Trin. ex Steud.) is a traditional building material in many parts of the world and provides service lives of more than 50 years when used for thatching. However, during the last decades a significant number of thatched roofs showed premature failure due to decay. Potential reasons for this are manifold but not clearly identified, yet. This monitoring project aimed therefore on investigating the moisture and temperature conditions within a thatched roof structure showing severe degradation after only seven years in service to obtain more information about the decay risk of reed and its potential causes. Highest moisture loads were found on the outermost layers of the North-faced roof, which also showed superficial growth of algae, lichens, and mosses. However, it stayed unclear if increased moisture content (MC)was the reason for or the consequence of decay. An increasedMCwas also found where the roof pitch turned from steep to flat. The use of so-called substitute sensors made from preservative treated wood turned out as a useful method to determine equilibrium moisture contents as well as time of wetness in reed structures and might be applied also for further field testing and monitoring with reed, straw, or other organic fibrous materials.
AbstractCalcareous materials such as limestone and lime-based mortars, widely used in the Built Heritage, are often subjected to degradation processes that can lead to loss of cohesion and material loss. Consolidation of these materials with liquid products via the surface is a common practice; however, the most used consolidation products (e. g. TEOS-based) show a poor physical-chemical compatibility with calcareous substrates. For application on calcareous materials, the so-called nanolimes, i. e. dispersions of lime nanoparticles in alcohols, are an alternative to TEOS-based products, thanks to their chemical compatibility with lime-based substrates. Nanolimes can help to recover a superficial loss of cohesion. However, their in-depth consolidation effect is not always satisfactory. Previous work has shown that a better deposition of lime nanoparticles in depth can be achieved by adapting the properties of the nanolime dispersion (kinetic stability and evaporation rate) to the moisture transport properties of the substrate, through optimization of the solvent. In this paper, freshly synthetized nanolimes were dispersed in pure ethanol and/or in binary mixture of ethanol (95 %) and water (5 %). These nanolimes were applied on Maastricht limestone and on a lime-based mortar by capillary absorption (method commonly used for laboratory tests) and by nebulization (method widely usedin situ). The aim of this research is to fill the gap between laboratory tests and on site application, providing an application protocol for restorers and professionals in the field. The research shows that results obtained by application by capillary absorption do not always correspond to those obtained by nebulization. This fact should be considered when deciding on the use of a consolidation surface treatment in practice.
Abstract This study deals with the effect of using different silicic acid ethyl esters (SAE) on diverse sandstones and to estimate their influence on the properties of the treated stones. Prismatic samples of Baumberger Sandstone (BST), Sander Sandstone (SST) and Nievelsteiner Sandstone (NST) with the dimensions 50 mm×50 mm×100 mm were treated with three different consolidating agents based on silicic acid ethyl ester (KSE 100, KSE 300, KSE 510) in three different procedures (vacuum, 1- and 5- time impregnation). The aim of this study is to demonstrate that differences in application, for instance varying stone consolidation agents, other treatment procedures as well as using sandstone samples with different binders (BST: calcareous, SST: clayey, NST: quartzitic), cause in each case different results concerning the strengthening effect and the success of a consolidation action. Laboratory measurements were performed on treated and untreated material in order to estimate the effectiveness of stone consolidation actions. To detect the influence of subsequent treatment procedures, water vapour diffusion resistance (WVDR) and capillary water absorption (CWA) measurements were carried out. Furthermore, the effectiveness of a stone consolidation was analysed by measuring ultrasound velocity, compressive strength, flexural strength, bond strength by pull-off and the porosity of the stone samples. Due to varying treatment procedures the investigated sandstones showed different petrophysical and mechanical properties (no strengthening effect up to “over-treating”). Different treatment procedures lead to increasing amounts of strengthening agent in the pore space of the investigated stones and as a result to higher values in WVDR (except BST and NST samples), ultrasound velocity and to an improvement in mechanical strength (except compressive strength of NST). This applies in particular to 1-time, 5-time and vacuum impregnated SST and 5-time treated NST and BST, regardless of the used stone strengthener. On the other hand, these different treatment procedures lead often to a decreased CWA and to a reduction in total porosity. The performed measurements indicate a development in strength in case of 5-time and vacuum treatment, but also an increase of the possibility of sealing the pores, especially for SST samples.
Abstract The Swedish National Research programme for Energy Efficiency in historic buildings was initiated in 2006 by the Swedish Energy Agency. This article gives an overview of the programme: objectives, projects and the general results of the programme. The research programme aims to develop knowledge, methods and technical solutions that contribute to energy efficiency in historically valuable buildings without destroying or damaging the historical value of the buildings, including decoration, furnishings, interiors or equipment. The programme is not limited to listed and monumental buildings but covers a wider range of historic buildings that account for a large part of the energy use in the building sector. For one and two-family houses, around 25 % of the energy use is associated with buildings built before 1945. The same number for multifamily houses is around 15 %. The programme is currently in its third consecutive four-year-stage. Previous four-year-stages were completed in 2010 and 2014. Over time, the scope of the programme and the projects have developed from mainly dealing with indoor climate control in monumental buildings towards addressing more general issues in the much larger stock of non-listed buildings. Technical research, based on quantitative analysis, dominate throughout all three stages, however most projects have had interdisciplinary components. The results from the programme have been presented in 31 journal papers, 67 conference papers, five books and five PhD theses. The projects have also contributed to CEN standards and resulted in a number of Bachelors and Master’s theses. An equally important long-term effect of the programme is that the number of Swedish researchers in the field have increased from practically none in 2007 to 18 senior researchers and twelve PhD students from ten universities in 2014. The research programme on Energy Efficiency in historic buildings is unique in an international context. Hopefully it can serve as an example for other countries on how to address an important interdisciplinary research challenge.
Abstract In recent years, thermal performance improvements have been applied to an increasing number of historic buildings towards the achievement of the legally binding Scottish carbon dioxide (CO2) emission reductions. Over 20 % of the built environment in Scotland was constructed pre 1919 and the targeting of fabric improvements in these buildings can pose a performance risk if inappropriate measures are applied. This paper discusses through a case study a Building Performance Evaluation (BPE) approach used in conjunction with the design process for refurbishment of a community owned historic building, located in Arisaig, Scotland. The community received funding to improve the energy performance of this nineteenth century stone building and committed to a 75 % reduction in CO2 emissions. BPE was conducted in 2014 as part of the design process and repeated post-refurbishment in 2015 to validate the design. The initial BPE identified high heat losses, inefficient heating and lighting systems that resulted in occupant discomfort, high running costs and consequently the loss of a community facility during the winter months. The resulting BPE quantified improvements to the building fabric, occupant comfort and reduced energy consumption, which advocated this design approach as a beneficial tool for informing historic building refurbishment.
Abstract In restoration work, the compatibility between old and new building material is the key point for sustainable repair of buildings or monuments. Consequently, conservation scientists are looking for an alternative method to the traditional procedures to determine the aggregate grading curve and the binder/aggregate-ratio of the historic material. The problem of using the traditional methods is the frequent major intervention in an existing building. These destructive methods are not allowed. Whereas, to get information about the historic mortar, a new technique, the digital image analysis (DIA), is applied in this paper. Moreover, small amounts of the historic material have already been prepared as thin sections and analysed with a microscope. Modern microscopy techniques allow investigations of quantitative and qualitative composition of historic material. Incentive of this work was to get all the required information to recreate the historic mortar by using the DIA with an open source program only at one thin section. In addition, to examine the accuracy and the significance of the DIA, all results were compared with a known mixture, and in a second test series, the results of the DIA were compared with the traditional methods. The results show that the DIA of thin sections of a historic mortar is highly effective for analysing decisive factors like the binder/aggregate-ratio and the grading curve of the aggregates. Furthermore, it is possible to analyse the mortar only by having one thin section using an open source program ImageJ. Especially in the case of carbonate rock as aggregate, DIA is the only method to analyse these characteristics of a mortar.
Abstract Local voluntary groups often play an important role in the day-to-day care for historic churches, therefore the perspective of laypersons is very relevant for their conservation. In this paper, we investigate laypersons’ valuation of historic buildings, their experiences of thermal comfort in those buildings and contrast this with their views on the appropriateness of energy efficiency measures. This paper presents four case studies of medieval churches in Groningen, Netherlands. We applied interviews and photo-elicitation to investigate the values held by local committees that take daily care of the churches in our sample. Our theoretical contribution lies in the combination of valuation studies and heritage approaches. Valuation studies is used to investigate the values that are attached to historic buildings by various stakeholders. We apply the ‘heritage-as–a-spatial-vector’ approach which focuses on using heritage as a resource and to position heritage in relation to developments in society. We conclude that for a more balanced assessment of historic buildings, laypersons’ valuations should be further integrated in heritage studies. In particular, community values and comfort needs should be more fully addressed in value assessments.
Abstract The restoration of St Martin church started end of the 1990’s by lacing-up the building with stabilizing steel frames. The layout of the lacing-up frames was inspired by the assumption that the observed cracks and deformations in the building were caused by differential settlements of the foundations. Further investigations during the final restoration works in 2011–2012 revealed that cracks were caused by inappropriate foundation interventions as part of an earlier restoration project in 1949–1950 as well as by non-balanced forces from the vaults. Based on the new findings the global restoration concept was adapted and strongly simplified.
Abstract The equestrian statue of D. José I, in Lisbon, is a masterpiece of the sculptor Joaquim Machado de Castro. It weights over thirty eight tons and was made in a single casting by Bartolomeu da Costa in a copper alloy (brass). After over two centuries exposure, the statue presented an unappealing heterogeneous appearance and showed some deterioration features that required attention. Preliminary studies showed that the deterioration phenomena were typical of copper alloys exposed to outdoor urban environments. The proximity of the seacoast also contributed to some specific decay mechanisms. The highly contrasting patterns of the superficial patinas consisted of black dense deposits covering an original cuprite layer side by side with the common green deposits of basic copper sulfates, hydroxides and chlorides. The highly corrosive nantokite was present in sheltered areas, where chlorides are able to accumulate. The conservation intervention included cleaning, mostly carried out with low pressure jets of round glass beads. Onsite tests were made to select the cleaning levels required to match the areas of black and green patinas. A reddish brown cuprite layer was found underneath most of the areas with black dense deposits, while it could only be perceived by transparency on the green covered areas. When a high contrast remained between the two areas, these were mitigated with the application of water colors during the final protection phase. Nantokite active areas were passivated with sodium oxalate after the entire statue was first washed with clean water and treated with lime water to leave an alkaline reserve to slow down the eventual corrosion process, and the sculpture rinsed with ethanol to accelerate its drying. The final protection was made with Paraloid B44 and microcrystalline waxes.
Abstract The forthcoming restoration campaign of the former house of the Flemish Baroque painter Pieter Paul Rubens (1577–1640) in Antwerp includes the design and construction of a new glass canopy. It is to replace the actual non-transparent roof structure, which was erected in the 1990s to protect the portico, separating the inner court yard of the house from the gardens, and especially its sculptural artworks from further material loss. The design parameters of the new glass canopy were evaluated based on the distribution probability of the rain on the portico as a function of rain intensity and wind velocity, while the rain distribution was determined based on the raindrop trajectories combining the vertical raindrop velocity and the horizontal drag from the wind. A minimum wind velocity of 40 km/h is required before rain can reach the feet of the sculptured artworks during intense rain showers. Statistical analysis of the hourly wind velocity and rain shower duration and intensity reveals a return period of approximately 4.2 years when the portico is protected by a glass canopy with identical dimensions of the actual provisory roof structure. Although the influence of intermittent wind gusts and squalls, which will more frequently drag along rainwater to the critical areas, and increase the amount of rainwater attaining the artworks during storms, could so far not be studied more in detail. The above risks are however considered acceptable to prevent future damage accumulation.
AbstractThe roof of the Ensor-gallery at Ostend is a cylindrical vault, constructed as a coarse grillage of reinforced concrete, with embedded reinforced concrete roof panels with prismatic glass tiles. The concrete ribs of the roof shell were heavily damaged by long term exposure to the chloride containing sea air, causing severe reinforcement corrosion. The paper presents the experimental data on the degradation, as well as the alternative approach used in the restoration project to avoid the loss of a major part of the authentic material. The approach is based on a combination of galvanic cathodic protection with embedded and bored in sacrificing anodes, the application of a chloride-inhibiting impregnation followed by a re-alkalizing treatment on the preserved parts, concrete repair and reconstruction with a self-compacting, shrinkage-compensating, polymer-modified repair mortar. Completely denuded steel reinforcement bars were replaced by glass fiber reinforced polyester rods.
Abstract This article reviews the carbonation process through biomineralization referred to as Microbial Induced Calcium Carbonate Precipitation (MICCP) for the conservation of carbonate stone monuments and historic building materials. This biological process widely occurs in nature as microbes produce inorganic materials within their basic metabolic activities. The first patent, which explained this method dates from approximately twenty-five years ago. Since then, different research groups have investigated substitute methodologies and various technical applications to provide a protective calcium carbonate layer on the surface of deteriorated historic buildings and stone monuments as well as to consolidate their inner weakened structure through this biodeposition process. The article reviews selected literature, highlights open queries and promotes discussion of a selection of issues, production mechanisms, application techniques, performance and bonding with stone structure. While many questions regarding this significant method have been focused in published sources, there are considerable possibilities for new research.
Abstract The restoration of the ruins of the Abbey-Tower in the city centre of Sint-Truiden in Belgium is presented as an example of the tedious and comprehensive task involved in all restoration or rehabilitation projects, where the extra cost of the restoration must be justified by the added value connected with the conservation of authenticity and with the contribution to sustainable development. The development and evolution of the project took 28 years, between the damages caused by the fire in 1975 and the start of the restoration in 2003. Since 2004, the restored ruin started a new life as a beacon of the city of Sint-Truiden, highly appreciated by tourists as well as by the inhabitants.
