The intensifying effects of climate change are becoming one of the main threats to cultural heritage, posing risks of degradation or destruction. Climate change is bringing complexity and uncertainty to ensuring the resilience of cultural heritage, and among risk mitigation measures digitalisation is regarded as a promising tool. However, the infrastructure required for the digitalisation process exerts significant pressures on the environment contributing to climate deterioration. To address these issues, this contribution developed a strong sustainability framework for the preservation of cultural heritage through digitalisation, for minimising environmental impacts and maximising the potential of preservation. To construct the framework, a literature review was conducted on efficiency and sufficiency concepts and existing approaches to sustainability of digitalisation in cultural heritage. To test the potential application and feasibility of the framework in driving environmental sustainability efforts within cultural heritage organisations, the case study of the Finnish Heritage Agency was analysed. The results showed that the understanding of the sustainability of digitalisation is not fully developed. Strong sustainability is hardly applied in practice, even though an inherent tendency for sufficiency especially in the appraisal stage was identified. It was highlighted that extensive stakeholder networks are required for advancing the sustainability of digital preservation. Ultimately, re-examining current practices and realigning stakeholders would be required for addressing the current challenges.