Historic buildings account for more than one-quarter of Europe’s existing building stock and are going to be crucial in the achievement of future energy targets. Although a drastic reduction in carbon emissions would slow climate change, an alteration in the climate is already certain. Therefore, the impact of climate change on retrofitted historic buildings should be considered in terms of occupants’ comfort, heritage conservation, and energy performance. Inappropriate interventions might weaken the potential of traditional climate adaptive solutions, such as thermal mass and night cooling, leading to higher risks of overheating in a warming climate. Similarly, retrofit solutions will change the moisture dynamics of historic envelopes, which might lead to moisture damages when combined with more extreme precipitation events. This paper reviews recent literature that provides evidence of climate change’s impact on retrofitted buildings, reveals potential future risks, and thereby sheds light on new factors influencing the decision-making process in the retrofit of historic buildings.

Climate change imposes great challenges on the built heritage sector by increasing the risks of energy inefficiency, indoor overheating, and moisture-related damage to the envelope. Therefore, it is urgent to assess these risks and plan adaptation strategies for historic buildings. These activities must be based on a strong knowledge of the main building categories. Moreover, before adapting a historic building to future climate, it is necessary to understand how the past climate influenced its design, construction, and eventual categories. This knowledge will help when estimating the implication of climate change on historic buildings. This study aims at identifying building categories, which will be the basis for further risk assessment and adaptation plans, while at the same time analyzing the historical interaction between climate and human dwelling. The results show some correlations between building categories and climate. Therefore, it is necessary to use different archetypes to represent the typical buildings in different climate zones. Moreover, these correlations imply a need to investigate the capability of the climate-responsive features in future climate scenarios and to explore possible further risks and adaptation strategies.

Energy retrofits can enhance the liveability and efficiency of historic buildings while preserving their historic and aesthetic values. However, measures like improved insulation and airtightness may increase their vulnerability to overheating and climate change may further worsen their performance in the future. This paper investigates indoor overheating risks brought by climate change in retrofitted historic buildings and proposes effective adaptation strategies. Firstly, local weather conditions are analysed to identify homogenous climatic zones. For each climatic zone, “a business-as-usual” emissions scenario is adopted, and most representative regional climate models are selected to obtain hourly output of future climate projection. A comparative study is adopted where typical alpine residential buildings, “Portici house”, are simulated with regard to future energy use and indoor thermal state using the dynamic model in EnergyPlus. Energy use and indoor thermal conditions are compared before and after energy retrofit, as well as under present and future climate conditions. The results demonstrate that retrofit interventions could significantly improve energy efficiency of historic buildings in both present and future scenarios. A change in climate together with retrofit interventions will, however, result in higher risk of indoor overheating in South Tyrol. Potential negative side effects of energy retrofit could be controlled by adopting adequate shading and ventilation approaches that minimise, or eliminate, the risk of overheating during high temperature periods while optimising historic buildings’ energy performance.

Climate change will affect future hygrothermal performance of buildings. This could lead to higher risks regarding energy optimization, thermal comfort and historic building conservation depending on the local climate, building construction and retrofit solutions adopted. This paper explores the risks brought by climate change on a typical residential historic building of South Tyrol. The results obtained show that, although the climate warming will reduce the future heating energy demand, an improvement of buildings’ energy performance will still be necessary to increase sustainability and ensure their continued use. Natural ventilation would suffice to prevent overheating in the studied location, but a further analysis is needed for warmer alpine regions. Regarding the moisture-related risks for the historic construction, mould growth should be considered when retrofitting a wooden wall and frost damage should be carefully studied in the case of sandstone walls.