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• A numerical model is developed to study indoor thermal conditions during heat waves. • Moisture buffering can have an important influence on the indoor thermal conditions. • Pre-cooling before the start of a heat wave can lower indoor temperature moderately. • Moisture-desorption cooling has a large potential in reducing indoor heat stress. Urban areas are increasingly impacted by the urban heat island effect, especially during heat waves. In the context of improving energy efficiency in buildings, passive and energy-efficient cooling methods are needed for reducing indoor heat stress and lowering building energy consumption during heat waves. In this study, a whole building simulation model that includes both moisture and heat transport in wall envelopes and indoor environment is developed. An analytical solution and two test cases are used to validate the developed model. The developed model is applied to study indoor thermal conditions in urban areas in Zurich, Switzerland in a hot summer. The results show that indoor temperature could not be accurately simulated when moisture transport in the wall envelopes is neglected. Due to the urban heat island effect, night ventilation is not sufficient to cool down the indoor environment during the heat wave in the urban area. The potential of precooling before the heat wave and moisture-desorption cooling from hygroscopic materials have been studied to reduce indoor heat stress in the urban area. The average operative temperature during the heat wave can be reduced by 0.43 °C by precooling before the start of the heat wave, whereas desorption cooling from hygroscopic materials could reduce the average operative temperature during heat waves by 1.31 °C. A combination of these two mitigation measures could lead to enhanced passive cooling effect. There is a large potential of using desorption of hygroscopic material to reduce heat stress during heatwaves, while minimizing energy consumption of buildings. [ABSTRACT FROM AUTHOR]

• Real historic buildings with artworks are examined. • Indoor environment, thermal comfort and energy performance were assessed. • The indoor environment is simulated and validated with on-site measurements. • Future indoor climate conditions were predicted for a 2050 scenario. • Future climate change will increase cooling demand. Climate change will affect the indoor temperature of historic buildings, impacting the preservation of artworks and the thermal comfort of users, and possibly leading to increased energy consumption. These buildings generate more emissions than new buildings and in most European countries, preservation principles take precedence over energy efficiency and the reduction of emissions. This research is a key topic for the mitigation of climate change and proposes a method for assessing the impact of climate change on the preservation of artworks, thermal comfort, and energy consumption. An experimental method was followed, combining analytical formulations, on-site measurements, and Heating, Ventilation and Air Conditioning systems in order to identify the adequate hygrothermal parameters for historic buildings. The climate change scenario predicted for 2050 was based on projected temperature variation. The case studies were Baroque churches, historic buildings located in the south of Europe. Data obtained from a monitoring campaign carried out in these churches was used to validate dynamic simulation models. The churches analysed showed an increase in cooling demand and a decrease in heating demand. Furthermore, in order to ensure human comfort and the preservation of artworks, it was necessary to implement active systems in operation for 12-hour periods. These results suggest an energy overconsumption, as the energy consumption for human comfort and artwork preservation was 50% higher than the energy consumption of active systems for the preservation of valuable historic objects. In addition, the annual energy consumption decreases for future scenarios for 2050 in the case of artwork preservation and thermal comfort, but increases by almost 15% for the preservation of works of art due to higher level relative humidity. Before historic buildings can be adapted, it is essential to understand the influence of the future climate on their design, construction, and environmental conditions. [ABSTRACT FROM AUTHOR]