4.1.6. Knowledge

Some interviewees suggested more knowledge through research and dissemination as a factor enabling mitigation in the cultural heritage sector. This is consistent with the literature, which emphasises the role of new knowledge and skills to develop new sustainable strategies for heritage conservation to face climate change uncertainty [51].

### 4.1.7. Energy Compensation Strategies

Some interviewees suggested the application of energy compensation schemes. This is where parts of a system that are ine fficient in their use of energy can benefit from the energy surplus produced by the e fficient parts. In relation to cultural heritage, this can be done at di fferent scales: city district and building. In the first case, di fferent buildings in the same district can share energy. For instance, the energy needed for historical buildings can be supplied by the surplus energy produced by new energy e fficient buildings or from o ff-site renewable sources of energy. GHG emission reductions through such a trading allowance is a cost-saving measure that was proposed by Cassar [51]. In the second case, one interviewee mentioned the possibility to meet the energy requirements for parts of a historical building where no refurbishment is allowed with the energy saved by improving the thermal performance of other parts of the buildings where modifications are permitted.

### *4.2. Barriers to Climate Change Mitigation In The Cultural Built Heritage Sector*

In addition to the factors found to enable climate change mitigation in the cultural built heritage sector, the interviewees also identified a number of barriers. These barriers were grouped into nine themes: 'economic factors', 'lack of regulation', 'value', 'material procurement and sustainability certification', 'user behaviour', 'loss of traditional skills', 'lack of knowledge', 'incompatible solutions' and 'diversity'. Figure 4 shows the number of interviewees mentioning each of the identified enablers as well as their percentages. Eleven interviewees, i.e., the 24% of the total number of interviewees, mentioned 'economic factors' as a barrier to climate change mitigation in cultural heritage sector. Table 3 provides examples of quotes from the interviewees in relation to each enabling factor.

**Figure 4.** Percentage of interviewees mentioning each barrier (*n* is the number of interviewees mentioning the barrier).

### 4.2.1. Economic Factors

The interviewees perceived economic factors as an important barrier to climate change mitigation in the cultural built heritage sector as restoring historical buildings is expensive. Thus, financial resources can help with conservation efforts when they are limited or not available. The lack of money to restore cultural heritage can also have negative consequences on the inherent historical, cultural and social values embedded in heritage sites. For example, an interviewee stated: "There is an economic aspect that prevails over the social, historical and cultural value." (Table 2). The adoption of cheaper solutions and in particular the loss of original material can influence the historical and cultural values of the site, as well as weaken the identity of a place. The economics of conservation is therefore an important criterion to consider when retrofitting historical buildings [43].

### 4.2.2. Lack of Regulation

A significant barrier perceived by the interviewees is the lack of regulation when adapting cultural heritage to mitigate climate change. The interviewees highlighted that stronger regulations are required to force the owners of heritage assets to adapt properly. An interviewee mentioned the example of a UNESCO WHS, where detailed guidelines were carefully designed and provided to the local community, but people did not follow them due to lack of enforcement. An interviewee from another WHS mentioned misinterpretation of the regulations as an issue, where the components of historical buildings were replaced with similar substitutes, albeit made of different materials characteristics, varying in shape and colour from the original components. Such substitution can decrease the authenticity of a heritage site. There are parallel examples between the information provided by the interviewees and case study examples reported in the literature. Yarrow [48], for instance, reported the concern of a conservation officer regarding a retrofitting where the building owners substituted the historical components for new ones claiming that they 'looked the same'. Devolution of the regulations to the local level was also mentioned as a problem by one interviewee, because, in some cases, a lack of financial and human resources put cultural heritage preservation in second place. The lack of protocols

and guidelines to help heritage managers adapt cultural heritage assets to climate change was also highlighted by Sabbioni et al. [8].
