**3. Methodology**

The methodology used in this study consisted of qualitative semi-structured interviews with experts in the preservation and managemen<sup>t</sup> of cultural heritage. In total, 45 interviews were conducted in the UK, Italy and Norway; three European countries with di fferent climates and heritage typologies. The selection of case study sites in those three countries allowed for triangulation of information. These sites were also selected as they form part of a larger project led by the first author with research on vulnerability and adaptation to climate change risks reported elsewhere [56,57]. The number of interviews was based on the principle of saturation in qualitative research, i.e., when it became evident that there was redundancy in the interviewees' answers and no new theme emerged, no additional interviews were conducted. The interviewees were academics and researchers working in di fferent universities and research centres, including experts involved in EU-funded projects focusing on climate change and cultural heritage (42%); practitioners working in organizations and institutions with a focus on the preservation of cultural heritage (27%), and managers, coordinators and professionals involved with UNESCO World Heritage Sites (WHS) (31%). Eighty percent of interviewees have more than 10 years of experience working on preserving cultural heritage and there were more males than women interviewees (Table 1).



The interviewees were from diverse backgrounds and specializations, including anthropologists, archaeologists, architects, conservation scientists, geologists, biologists, managers and coordinators of heritage sites, sustainability o fficers and urban planners. The structure of the interviews was prepared in advance, but during the interviews the order and number of questions varied according to the interviewees' expertise and answers (i.e., the interviews were semi-structured). Introductory questions on the professional background of the interviewees were followed by a list of questions focusing on themes related to climate change mitigation in the cultural heritage sector: GHG emission reductions at heritage sites, improvement in the energy performance of historical buildings, sustainability of materials, and methods used during conservation practices. Ethical approval for this research was obtained through the University of the West of Scotland procedure. The interviews were audio recorded and then transcribed, analysed and coded using the NVivo software (Version 11, QSR International (UK) Limited, Daresbury, Cheshire, UK). The interviews were conducted in English in the UK and Norway and in Italian in Italy. The Italian interviews were not translated during the coding process but some quotes were translated for the purpose of displaying samples of interview quotations in Tables 2–4.




**Table 2.** *Cont.*

### **Table 3.** Barriers in mitigating climate change in the cultural built heritage sector.



**Table 3.** *Cont.*


**Table 4.** Best-practice examples of cultural heritage refurbishment measures to mitigate climate change, as proposed by the interviewees.

The interviews transcripts were coded using the categories: "enablers", "barriers" and "best practice". Subsequent to coding, the transcripts were used to search for patterns in the data. This search for patterns in the coded interview transcript led to the identification of themes representing the factors enabling and those impeding climate change mitigation in the built heritage sector was then determined by analysing the coded interview transcripts and are displayed in Figure 1.

Examples of quotes from the interviewees in relation to each of the identified themes are shown in Tables 2–4 to explain the selection of specific themes and the categorisation of the information provided by the interviewees. These representative quotes were carefully selected and shortened to reduce the word count without compromising their meaning. The use of direct quotations allows the reader to have a better understanding of the respondents' perceptions about climate change mitigation. The results do not present commonalities or differences amongs<sup>t</sup> the interviewees, as the purpose of this paper is to highlight the factors enabling or constraining climate change mitigation in the cultural heritage sector, including examples of best practice for its implementation, as well as to inform decision-makers and to identify research needs. Figure 2 summarises the steps involved in this qualitative methodology:

**Figure 1.** List of primary and secondary coding.

**Figure 2.** The qualitative methodology used in the current research.

### **4. Results and Discussion**

The investigation first examined the interviewees' perceptions to identify the factors that enable and those that act as barriers to climate change mitigation in the cultural built heritage sector. During the interviews, the participants addressed issues such as reducing carbon emissions and the transition to a low carbon economy, improvements in the energy performance of historical buildings, the preservation of heritage values, the sustainability of materials and methods used for refurbishing and restoring heritage assets.

### *4.1. Enablers of Climate Change Mitigation in the Cultural Built Heritage Sector*

The interviewees were positive about adapting the cultural built heritage to mitigate climate change and identified a number of factors that enable this. These factors were grouped into six themes: 'economic factors', 'legislation and regulations', 'sustainable refurbishment strategies', 'sustainable transport strategies', 'user behaviour', 'knowledge' and 'energy compensation strategies' (see Table 2). Figure 3 shows the number of interviewees mentioning each of the identified enablers. For example, 13 interviewees, i.e., the 29% of the total number of interviewees, mentioned 'economic factors' as an enabling factor to climate change mitigation in the cultural heritage sector.

**Figure 3.** Percentage (and number) of interviewees mentioning each of the different enablers of climate change mitigation. (*n* is the number of interviewees mentioning the enabler).

### 4.1.1. Economic Factors

The interviewees perceived as important the economic factors that enable the implementation of strategies to mitigate climate change. Government incentives was the most mentioned measure by the interviewees. Such incentives are used to encourage people to make interventions compatible with the heritage assets instead of choosing market-forced solutions that are often not compatible with the heritage values. The interviewees found that the wider (non-expert) public can be reluctant to restore traditional windows due to the high costs involved and the belief that the restored windows will be less energy e fficient than alternative new double-glazed windows. However, as mentioned above, the results of previous research concluded that window replacement is not necessarily a better energy saving measure. Considering the energy used in the life cycle of the windows, restoring, instead of replacing the windows, can be a better choice [34]; in addition, the energy cost related to the transport of the new elements is avoided. The interviewees also emphasised that restoration e fforts compatible with the heritage building should be encouraged with the help of incentives so that people are willing to pay more for them. This is particularly the case when the money invested in the refurbishment efforts can be recovered in the long-term from the energy saved subsequent to the refurbishment efforts. The interviewees suggested restoring and maintaining the original historical materials as an opportunity for improving local economic sustainability against the importation of foreign materials and for maintaining as well as increasing traditional expertise locally.

### 4.1.2. Legislation and Regulations

According to the interviewees, having more legislation, regulations and guidelines would facilitate climate change mitigation in the cultural heritage sector. New regulations were requested not only at the international, national and regional level, but also in municipalities and at cultural heritage sites. In fact, it was even suggested to include climate change mitigation in site managemen<sup>t</sup> plans, but also to increase policy requirements for mitigation actions in public buildings. A specific request by the interviewees was the need to improve the regulatory structure behind carbon usage reports and post-performance evaluations in order to better monitor the energy consumed in refurbished buildings during the use-phase and to compare it with the energy usage that was predicted prior the refurbishment. Consistent with this information gathered from the interviewees, there is agreemen<sup>t</sup> in the literature that ambitious policies can significantly reduce the energy use in buildings [58], and that for successful mitigation in the cultural heritage sector, policy actions at both the regional and local levels are needed [7,59]. In addition, Yarrow [48] highlighted a potential conflict between legislation promoting preservation of cultural heritage and that requiring a reduction of energy consumption in buildings, hence the di fficulty of applying general policies to historical buildings.

### 4.1.3. Sustainable Refurbishment Strategies

The interviewees suggested a number of actions aimed at improving sustainability and thus at reducing the GHGs emitted by the cultural built heritage sector. Examples of sustainable actions in relation to the refurbishment of historical buildings include the selection of environmentally friendly and natural materials, especially if originating from local sources, recycling and reusing materials, avoiding the use of harmful chemical substances and minimising the generation of building waste. However, sometimes it is di fficult to understand whether one way to refurbish a historical building is more sustainable than another is. For this reason, the sustainability of the materials and refurbishment actions should be assessed using the LCA methodology prior to the implementation of the refurbishment e fforts. This would provide a better understanding of the energy and CO2 emissions associated with a specific intervention. Such an approach, however, should also consider the embodied energy in the historical materials that are proposed to be replaced. The latter is consistent with Webb [43] who mentioned the lack of consideration of the embodied energy of historical buildings during retrofitting. Hence, further work is required on the evaluation of the sustainability of the materials and methods used during refurbishment in the built heritage sector, as the LCA approach has been applied mostly on new construction rather than on historical buildings [48], a gap in knowledge which Bertolin and Loli [37] also had previously highlighted. In addition, when applying the LCA approach to the heritage sector, the historical and cultural values need to be considered and added as a parameter in the evaluation of the solutions to be adopted. These values are often neglected and priority is often given to new technologies and to materials targeted at energy reduction [37], without considering the sustainability of the cultural built heritage sector in a holistic way as mentioned by an interview in the following quote: "We need to evaluate (...) sustainability through 360 degrees." (Table 1).

### 4.1.4. Sustainable Transportation Strategies

The interviewees also emphasised the need to improve environmental sustainability at cultural heritage sites by reducing CO2 emissions through the promotion of sustainable transport to and from the sites as well as within the sites. This can be accomplished, for example, by promoting cycling and public transportation, as well as by closing historic town and city centres to domestic vehicles. The latter can also contribute to decreasing air pollution and thus improving air quality, as well as reducing the associated decay on monuments and the facades of historical buildings [60].

### 4.1.5. Change in User Behaviour

User behaviour has a significant impact on the e ffectiveness of mitigation measures adopted on historical buildings. The interviewees recommended to encourage users, e.g., occupants and visitors, to behave in a more sustainable way and mentioned the need to raise awareness through engagemen<sup>t</sup> to ensure that mitigation is e ffective. Users should be educated in energy and water saving measures, reusing and recycling materials, and decreasing their waste and emissions. This can start through simple things such as wearing a jumper inside the building in the winter and thus reducing the use of heating, instead of wearing only a t-shirt, for instance. Berg et al. [38] emphasised the importance and potential of user-driven energy e fficiency measures in historical buildings and that user behaviour should always be taken into account, as the occupants play a central role in the day-to-day managemen<sup>t</sup> of the building. The Intergovernmental Panel on Climate Change (IPCC) [58] further highlighted that in developed countries, behavioural change could decrease energy use by up to 20% in the short-term and by up to 50% by the middle of the 21s<sup>t</sup> century.
