**5. Conclusions**

Mitigating climate change by reducing GHG emissions is now urgen<sup>t</sup> to prevent future—and reduce current—danger to cultural heritage resources. This needs to be accomplished, in part, by reducing the energy used by cultural built heritage assets, notably through improvements in their energy e fficiency. Organizations such as UNESCO, ICOMOS, ICCROM, IPCC and the European Commission promote actions to cut GHG emissions in the cultural built heritage sector. This paper analysed the perceptions of cultural heritage experts on the issue of adapting the cultural built heritage to mitigate climate change. Specifically, it reports on the factors enabling and those acting as barriers to mitigate climate change, as perceived by the managers of heritage sites and experts working on the preservation of cultural heritage in universities, research centres and governmental institutions.

A common view amongs<sup>t</sup> the interviewees was that climate change mitigation in the heritage sector is necessary but challenging. Most research accomplished to date investigated measures to mitigate climate change by reducing the energy consumption of cultural heritage buildings, but there is limited research on the identification of the challenges to overcome in this regard. This paper provides a better understanding of what needs to be provided and prioritized for the mitigation of climate change in the cultural built heritage sector to take place. In summary, this study identified the following barriers constraining climate change mitigation in the field of cultural heritage: economic factors, lack of regulation, heritage values as it can limit the type and scope of refurbishment, inadequacies in material procurement and sustainability certifications, inefficient use of energy due to building occupants' behaviour, lack of knowledge, loss of traditional skills, the adoption of solutions incompatible with the assets and hence causing further damage, diversity of heritage resources and hence the difficulty to identify solutions that are fit for all. The factors enabling climate change mitigation that could help to overcome some of those identified barriers include economic resources and incentives, legislation and regulations, sustainable refurbishment strategies, sustainable transportation strategies, change in user behaviour, knowledge, and energy compensation strategies. Figure 5 provides a graphical summary of the factors enabling and constraining climate change mitigation in the field of cultural heritage.

This research emphasised that mitigating climate change in the cultural built heritage sector is a complex issue and requires a holistic approach for the identification of sustainable strategies to reduce GHG emissions. In this regard, ambiguities still remain on the consideration of heritage values and the energy embodied in historical materials, as well as the potential of traditional passive measures when adapting heritage buildings to mitigate climate change. This study improves our qualitative understanding of the key themes raised by stakeholders and can be used as a basis for further research seeking to quantify the effectiveness of best practice in climate change mitigation in the cultural heritage sector. Specifically, further research should be developed on adaptation strategies that consider the balance between reduction of decay and improving the energy consumption of historical buildings [64]. More research should also be conducted on the use of traditional solutions for improving energy efficiency, and on the compatibility (or lack) of new technologies and materials with the historical ones. Historical buildings work differently from modern buildings. Further research is required on the re-use of traditional passive measures such as wind chimneys, greenhouses, passive ventilation and heating, to name a few, and thus avoiding carbon intensive energy consumption, as well as on the promotion of sustainable natural resources, e.g., wind and sunlight. This could be done by understanding the level of energy efficiency achievable by different types of heritage (e.g. ancient castles and monuments versus non-ancient historical assets) in relation to their values, integrity and authenticity.

Monitoring before and after retrofitting and/or refurbishment works should be encouraged to estimate properly the energy consumption and the energy payback period from the use of renewable sources post intervention. This includes the need to rectify the current energy certification process, which does not consider the energy used to transport materials when historical materials are replaced by new ones in their calculations; the need for LCA evaluations before refurbishing historical buildings to understand the impact of the proposed solutions on the environment; and the need to promote the use of natural materials to avoid toxic chemicals.

A decrease in energy consumption also needs to be promoted through changes in user behaviour (e.g. wearing appropriate clothes and heating less, reducing the heating of rooms when not used, use more natural illumination and less electricity), which can be implemented with the use of information and communication technology (ICT). More knowledge needs to be disseminated and collaboration between different countries and at different levels should be encouraged, from the governmental

to the end user. Including increasing awareness and cooperation between heritage organizations, governmental institutions, research centres and academia.


**Figure 5.** Summary of the research findings. **Author Contributions:** Conceptualization, E.S., A.G., C.B. and J.H.; Data curation, E.S.; Formal analysis, E.S.; Funding acquisition, E.S., A.G. and J.H.; Investigation, E.S.; Methodology, E.S. and A.G.; Project administration, A.G.; Resources, J.H.; Supervision, A.G., C.B. and J.H.; Validation, C.B.; Visualization, E.S.; Writing—original draft, E.S.; Writing—review & editing, A.G., C.B. and J.H.

**Funding:** The University of the West of Scotland provided a university studentship to support the doctoral studies of the first author. The Postdoctoral and Early Career Researcher Exchanges (PECRE) funding scheme of the Scottish Funding Council and awarded by the Scottish Alliance for Geoscience, Environment and Society (SAGES) supported the academic exchanges of the first author to Italy and Norway.

**Acknowledgments:** We thank all the interviewees for their time and information, and Historic Environment Scotland for the grey literature provided. We are also grateful to The Institute of Atmospheric Sciences and Climate, National Research Council of Italy (ISAC-CNR) in Bologna and the Norwegian University of Science and Technology (NTNU) in Trondheim where two academic exchanges were conducted, and to the Scottish Funding Council via the Scottish Alliance for Geoscience, Environment and Society (SAGES) who funded those two academic visits.

**Conflicts of Interest:** The authors declare no conflict of interest.
