Purpose: Energy use in buildings needs to be reduced to meet political goals; however, reducing energy use can conflict with heritage preservation objectives. The purpose of this paper is to demonstrate a method that combines quantitative and qualitative analyses of the potential of energy savings in an historic building stock. Specifically, this study examines how requirements of historic building preservation affect the energy saving potential on a building stock level. Design/methodology/approach: Using the World Heritage Town of Visby, Sweden as a case study, this paper illustrates a step-by-step method as a basis for implementing energy savings techniques in an historic building stock. The method contains the following steps: categorisation of a building stock, definition of restriction levels for energy renovation scenarios and life cycle costs optimisation of energy measures in archetype buildings representing the building stock. Finally, this study analyses how different energy renovation strategies will impact heritage values and energy saving potentials for different categories of buildings. Findings: The outcome of the study is twofold: first, the method has been tested and proven useful and second, the results from the application of the method have been used to formulate differentiated energy renovation strategies for the case study. Originality/value: The study shows that it is possible to integrate techno-economic analysis with assessment of heritage values in a given building stock in order to facilitate a strategic discussion balancing policies and targets for energy savings with policies for the preservation of heritage values. The findings will contribute to sounder policy development and planning for historic building stocks.

The historic building stock is not homogeneous, which implies a need for differentiated energy renovation strategies in order to balance energy efficiency requirements and building conservation goals. This paper presents a new method for developing a base for differentiated energy renovation strategies for heritage-classified multifamily building stocks. Our suggested method combines different building databases using an extract, transform and load (ETL) technology. The method for this study was tested on the available information for heritage-designated and -classified multifamily buildings in the municipality of Stockholm, Sweden, and in the county of Halland, Sweden. The two cases reflect the heterogeneity of the Swedish Building stock. An important achievement is that the results visualise the relationship, not detectable before, between energy use, energy performance, year of construction and heritage classification within each of the selected building stocks. A specific result is that the energy-saving potential in the older building stock is insignificant in relation to the entire stock. The results contribute to an improved understanding of relationships both within and between the two historic building stocks, which is useful for developing differentiated energy renovation strategies.

This study showcases the digitalization of Löfstad Castle in Sweden to contribute to preserving its heritage values. The castle and its collections are deteriorating due to an inappropriate indoor climate. To address this, thirteen cloud-connected sensor boxes, equipped with 84 sensors, were installed throughout the main building, from the basement to the attic, to continuously monitor various indoor environmental parameters. The collected extensive multi-parametric data form the basis for creating a parametric digital twin of the building. The digital twin and detailed data analytics offer a deeper understanding of indoor climate and guide the adoption of appropriate heating and ventilation strategies. The results revealed the need to address high humidity problems in the basement and on the ground floor, such as installing vapor barriers. Opportunities for adopting energy-efficient heating and ventilation strategies on the upper floors were also highlighted. The digitalization solution and findings are not only applicable to Löfstad Castle but also provide valuable guidance for the conservation of other historic buildings facing similar challenges.

In order to achieve environmental goals, the impact of the European building stock on the environment needs to be reduced through renovation measures. However, regarding heritage buildings, the choice of measure(s) must simultaneously consider the preservation of cultural and historical values. Besides the impact on such values, energy-efficiency measures can result in increased risks for moisture damage and the diminishment of indoor environmental quality. Furthermore, a measure’s impact on a building’s environmental print is not self-evident, adding further to the difficulty of choice. This paper synthesizes and reviews existing literature on choosing renovation measures for heritage buildings and literature dealing with choosing the combination of renovation measures. The paper shows that several publications present strategies/ methodologies for the choice of renovation measures for heritage buildings. However, none are holistic, and none detail the choice from a holistic perspective. Furthermore, several publications have investigated the impact of different combinations of measures on older buildings. However, few consider cultural values. Through this literature review, this paper states the need for a holistic approach to choosing renovation measures for heritage buildings.