Twelve Years of Energy Efficiency in Historic Buildings in Sweden

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.

Quantitative Analysis of Historic Mortars by Digital Image Analysis of Thin Sections

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.

Valuation of Medieval Churches; Taking Account of Laypersons’ Views

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.

Building Performance Evaluation – A Design Approach for Refurbishment of a Small Traditional Building in Scotland

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.

Guidance for Finding a Sustainable Balance between Energy Savings and Heritage Preservation When Retrofitting Heritage Buildings

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.

An Assessment Method for Certified Environmental Sustainability in the Preservation of Historic Buildings. A Focus on Energy Efficiency and Indoor Environmental Quality in the Italian Experience of GBC Historic Building

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.

An Investigation of the Energy Efficiency of Traditional Buildings in the Oporto World Heritage Site

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.

Behaviour of Pigeon Excreta on Masonry Surfaces

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.