Algae growth on historical building surfaces poses aesthetic and structural challenges. Quagliarini’s Modified Avrami model establishes a rela-tionship between substrate temperature, relative humidity (RH), and algae growth under controlled conditions. However, when applied to real weather datasets, it fails to directly capture the influence of dynamic cli-matic factors. This study bridges this gap by analysing the relationship between temperature, RH, and rainfall on algae risk. Using Brussels cli-mate data, a 1-D HAM simulation was conducted on two historical build-ing types across eight orientations and four wall factors, with algae risk assessed via the modified Avrami model. Key findings include: (1) algae growth follows a sigmoidal pattern, peaking between Years 2–4, with higher risk on S, SW, and W façades; (2) growth becomes significant when temperatures exceed 12°C and RH surpasses 70–75%, with peaks in June and July; (3) 60–85% of growth occurs 24–48 hours after rain-fall; (4) a risk prediction model was developed to assist design decisions and initial risk screening. These findings enable preliminary algae risk as-sessments based on climate conditions, assisting design decisions and ini-tial risk screening.

Historic residential buildings constructed during the early 20th century account for high energy consumption and usually inadequate thermal comfort. Refurbishment approaches usually involve additional thermal installation or renovation of the heating system, which requires consensus within the residential community.

Interior insulation is an exception, since it can be applied indoors within a single apartment while preserving the historic value of the façade. However, indoor thermal insulation raises concerns from condensation.

This research analyses the insulated indoor structures’ hygrothermal performance, application possibilities and associated condensation risks of thermal insulation types with various vapor permeabilities. The research includes the analysis of construction junctions and selected critical areas, such as historic box-type external windows. The simulations were performed in both DELPHIN and THERAKLES software to accurately assess and evaluate the hygrothermal behavior over a ten-year period.

Findings indicate that indoor insulation can reduce the annual heating energy demand by approximately 20%, while also improving wall surface temperature, maintaining walls warmer in Winter and cooler in Summer. However, applying internal insulation may also result in cold spots in adjacent structures, increasing the risk of condensation and mold growth. The research highlights the potential positions within the junctions where the risk of condensation is the highest and confirms the importance of long-term scenario modelling for condensation risk mitigation.

Hygrothermal numerical simulations are essential for assessing the long-term performance of building structures under varying climatic conditions. However, discrepancies between simulated and measured relative humidity (RH) profiles, particularly at subzero temperatures, negatively impact the reliability and introduce uncertainty for practitioners in hygrothermal assessments. While both simulations and measurement sensors calculate RH similarly above freezing, referencing liquid water, differences emerge below freezing due to variations in calculation methods. Simulations typically account for ice formation at subzero temperatures, whereas measurements reference supercooled liquid water, causing RH values to diverge as temperatures decrease. This novel study investigated how RH calculation methods influence simulation accuracy in cold climates. Converting subfreezing RH values from the climate cabin to align with simulations improves agreement and validation accuracy. The results showed that the RH calculation method at subzero temperatures have a minimal impact on simulation end results or mold growth risk, allowing direct use of sensor data referenced to water. As temperatures decrease, the difference between RH values with respect to water and ice increases, making it advisable to use ice-referenced values in extremely cold conditions (< -30°C) for better accuracy.

The southern regions of China host a substantial number of open-air limestone cultural relics. Limestone, primarily consisting of CaCO3 (calcite), is highly susceptible to dissolution, making the physical environment a critical factor in the preservation of these relics, particularly in high-humidity environments containing sulfur oxide gases. To simulate and assess the dissolution risks of limestone relics under fluctuating thermal and humidity environment, this study take the Yangshan Stele as an example. A heat and moisture transfer model was devoloped to simulate the thermal and humidity distribution across various parts of the stele's surface. The relative humidity of these points at different positions on the surface of the stele were calculated and if they were in a high humidity the state was further evaluated. The simulation results show that the proportion of the annual time of the Yangshan Stele in dissolution risk states is 0.39-2.89 %. The annual dissolution time of the north and west facade is slightly higher compared to the other facades. The dissolution risk in January, February and June was high compared to other months. According to the Arrhenius equation, the reaction rate constant k of the dissolution reaction in summer is 1.89-2.04 times higher than that in winter. Therefore, we should focus on strengthening the daily monitoring and protection during the month with high incidence of dissolution, especially for the lower part of the body, the north and west facade.

The impacts of climate change are becoming increasingly evident, with more frequent heavy rainfall events and rising temperatures significantly affecting building envelope performance and durability. Evaluating the hygrothermal performance of building envelopes under future climate projections is essential for both the retrofit of existing buildings and design of climate resilient new buildings. Although moisture-induced failures of exterior walls are a common issue in Turkey, the hygrothermal performance of external walls under future climate projections has not been explored for any climate region in the country. The response of building envelope components to future climate loads based on hygrothermal performance indicators and damage prediction models are a key element to predicting climate change impacts on building envelopes. In this study, performance indicators were established for assessing the hygrothermal performance of building envelopes using HAM models. North American and European standards were reviewed to identify the relevant hygrothermal performance indicators and related threshold values. Additionally, a review of literature focused on simulating the hygrothermal performance of external walls was completed to verify the damage prediction models used and related performance indicators in relation to wall assembly types examined. A national moisture control standard is available in Germany whereas European standards for hygrothermal performance assessment are valid across the EU as well as in Turkey. Performance indicators such as mould growth index, wood deterioration, and frost risk damage are widely used and often integrated in the HAM models post-processing tools. In this study, the importance of hygrothermal performance indicators for predicting the impacts of climate change on building envelopes is highlighted as a useful approach to advancing resilient design practices.

Energy consumption of buildings is greatly affected by the criteria used for the indoor environment (temperature, ventilation, and lighting) as well as the operation and design of the building. The building sector plays a crucial role in attaining the energy and environmental goals, since around 1/3rd of the total energy is used to heat, cool, ventilate, and control humidity to meet the thermal comfort demand of the occupants.

This research paper presents a comprehensive study of the dynamic simulation of a single-story family house situated in two distinct geographical regions: Budapest, Hungary and Bareilly, India. The investigation includes dynamic simulation according to EN 15026:2023 standard to evaluate a family house's energy performance and hygrothermal performance under varying climatic conditions, considering hourly weather data and occupancy-specific internal load available in Wufi library. The research methodology involves a 3D building model created within Wufi Plus software for the representation of family houses based on traditional methods and standard engineering structures, incorporating architectural and structural aspects, as well as mechanical HVAC systems. Overall, 6 case study were developed to explore how these parameters influence indoor thermal performance, moisture management, and energy efficiency, specifically focusing on the various thermal insulation and building materials.

The results demonstrate a substantial reduction in heating and cooling demand following the application of thermal insulation. The best results were achieved in the Bareilly zone, heating demand decreased by up to an impressive 95%, while cooling demand was reduced by 50% comparing the insulated cases to uninsulated cases. Conversely, in Budapest, insulation resulted up to 86% reduction in heating demand but led to a 45% increase in cooling demand. The IAQ improves after thermal insulation lies 40% in class IInd.

This research contributes valuable insights into the construction industry on using insulation and appropriate building materials to enhance energy efficiency and indoor climate control. The findings provide essential support to researchers, architects and structural designers in creating sustainable buildings with optimized energy performance, aligning with global climate goals.