Conference Agenda

Thermally upgrading heritage buildings often involves a delicate balance between modern performance requirements and the need to preserve historical and architectural value. Numerical simulations can aid in this decision-making process by weighing savings and benefits against costs and risks. This study explores potential improvements for heritage single-glass windows by adding secondary glazing. Secondary glazing is frequently considered a viable solution for enhancing the thermal performance and energy efficiency of heritage buildings without compromising their historical integrity. Studies have shown up to a 60% reduction in heat loss compared to the original single glazing. To ensure the appearance and character of heritage buildings are maintained, custom solutions are often developed to be minimally intrusive and in line with the unique features of the original windows. However, while secondary glazing can be cost-effective in the long run due to the energy savings it provides, the initial costs can be high. As an alternative, replacing the original single glazing with thin, high-performing double glazing, such as vacuum glazing, is considered.

This study compares the thermal performance of adding secondary glazing versus replacing the original single glazing in the original frame with advanced double glazing for two common types of Dutch heritage windows: thin steel windows and wooden sash windows. For each window type, different configurations and solutions are considered:

1a. The original window with single glazing (reference)

1b. Original windowpane replaced by double glazing

1c. Original windowpane replaced by vacuum glazing

2a. Adding secondary glazing to single glazing

2b. Secondary glazing with double glazing

2c. Secondary glazing with vacuum glazing

For the secondary glazing configurations (cases 2a-2c), the distance of the air gap between the original windowpane and secondary glazing is taken as an additional variable.

To calculate the thermal performance of the different configurations, 3D-thermal simulations are performed on the window in a massive masonry wall, explicitly accounting for heat transfer by radiation. These simulations, however, do not consider heat transfer by air infiltration and exfiltration. To put the results in perspective, considering the poor airtightness of common heritage windows, the thermal simulation results are complemented by a simple hand calculation to assess additional heat losses by air flow. The results indicate that heat losses due to a lack of airtightness are of the same order of magnitude as heat losses by conduction. Consequently, adding airtight secondary glazing, even with limited thermal performance, outperforms replacing the original single windowpane with high-performing glazing.

The demand for energy-efficient buildings is rapidly increasing due to growing environmental concerns and rising energy costs. Cooling requirements have become a key factor in the design of energy-efficient buildings, as they significantly affect overall energy consumption and environmental sustainability. However, energy efficiency regulations in Estonia are vague regarding the impact of façade cladding leaving a gap in understanding how façade choices affect building performance.

TThe primary goal of this study is to examine how different façade cladding materials influence the cooling needs of residential buildings in Estonia. The test house in this study has an energy demand of 118 kWh/m² per year, a measure that represents the total energy consumption for heating, cooling, and other residential needs. The study focused on two different types of façade cladding: black stone cladding and light wooden cladding. These materials were chosen due to their differing thermal properties and the way they interact with heat from the environment. On-site testing was conducted to gather real-world data under natural weather conditions, providing a more accurate picture of how these materials affect cooling performance.

In this study, the air gaps behind stone and wood cladding were monitored to determine their impact on thermal performance. Temperature and relative humidity measurements were taken from buildings oriented in different cardinal directions to account for variations in solar exposure and the resulting heat load. Gathered temperature and relative humidity were inserted to simulation in IDA ICE 4.8.

The author hypothesized that the temperature beneath stone cladding would be 20% higher, leading to at least a 10% increase in cooling demand. Both hypotheses were confirmed.

This study examines the thermal and energy efficiency of multi-layer transparent building envelope components enhanced with advanced latent heat storage materials. A thin layer of solid-solid phase change material was integrated into smart-glazing technologies to improve energy performance by storing and releasing the latent heat during phase transitions within the solid state and simultaneously ensuring structural stability. Numerical simulations were conducted using the finite volume method within computational fluid dynamics (CFD). The numerical results were validated against experimental data. Thereafter, the system was analyzed across a range of transient temperatures for various climatic conditions. The findings highlight how the transparency fraction and energy savings of the system are influenced by the thermal behavior of the solid-solid phase change material and variations in climatic conditions. Substantial differences in energy performance were observed between climatic zones classified under the Köppen-Geiger system, emphasizing the need to tailor the design and material selection to regional conditions. This research provides valuable insights into the development of innovative, energy-efficient transparent building envelope components, contributing to sustainable building practices across diverse climates.

Building façades are essential to urban aesthetics and functionality, yet they face persistent degradation from weathering, biological colonization, and particulate deposition. Beyond their architectural role, façades play a key role in hygrothermal regulation and indoor comfort. Addressing these challenges, photocatalysis offers a promising solution, leveraging light-driven redox reactions to degrade pollutants while imparting surfaces with self-cleaning, biocidal, and air-purifying capabilities. These processes often induce superhydrophilicity, enhancing resistance to fouling. However, conventional photocatalytic systems often rely on costly, non-renewable materials. This study proposes a sustainable alternative: a marine-derived photocatalyst based on calcined oyster shells (biogenic lime), functionalized with titanium dioxide (anatase TiO₂) and silver (Ag) via incipient wetness impregnation, followed by calcination (at 450 °C with a 2-hour ramp-up and a 2-hour hold), benchmarked against pure TiO₂ as a reference. The marine-based material was applied to lime mortar coated with silicate paint and characterized via SEM-EDS. The photocatalytic performance was assessed through rhodamine B degradation under UV light and water interaction tests, including contact angle measurements and microdrop absorption time. The marine-based photocatalyst achieved 30–40% of the self-cleaning efficiency of commercial TiO₂ when normalized considering the color change observed for the first, despite having roughly half the photoactive atomic concentration, indicating potential for future optimization.

Buildings significantly impact climate change, accounting for approximately 26% of energy-related greenhouse gases globally in 2021. As a result, improving their energy efficiency has become one of the primary policy goals for many countries worldwide; the EU, for example, plans to retrofit 35 million buildings by 2030 to improve their energy efficiency. This has resulted in the ongoing widespread adoption of insulation systems in building stocks. Many existing buildings, however, used solid walls which absorb and release liquid and water vapour both internally and externally. Introducing insulation systems can alter this hygric behaviour across the wall section, increasing the risk of moisture-related structural and health problems. Despite these risks, there is a deficit of scientific, evidence-based guidance and regulation on the topic, despite the existence of numerous studies on the hygrothermal behaviour of solid-walled structures.

This review reports and collates the existing international literature on the influence of insulation types and systems on the hygrothermal performance in solid wall structures, mainly considering factors such as moisture movement and thermal comfort. The scope includes laboratory, test cell and field trial experiments as well as simulation studies. Targeted hygrothermal behaviours, key wall locations and threshold parameters are reported. The strengths and weaknesses of the different approaches are highlighted and research gaps identified.

The work will lay the basis for the development of an experimental and simulation study of the hygrothermal behaviour of different insulation types and systems for solid walled structures in a temperate maritime climate, using Ireland as a case study.

Reducing reliance on active climate control through mechanical systems is essential to mitigating climate change. Thermochromic materials, which adjust solar absorptance based on surface temperature, are a promising solution for climates with significant seasonal variations. In this study, thermochromic coatings based on SiO2 and TiO2 matrices were devel-oped, featuring a protective layer of photocatalytic P25 titanium dioxide to enhance resistance to photodegradation. Applied to ceramic roof tiles, the coatings were subjected to accelerated aging tests according to ASTM D7897-23 and characterized for their solar reflectance according to ASTM E903-20 and ASTM G173-23. The results were incorporated into EnergyPlus simulations to evaluate the impact of the coatings on an of-fice building model in Madrid, Budapest, and Oslo, representing differ-ent climate zones. The results showed that accelerated aging reduced the contrast between the two-color phases of the thermochromic pigments, affecting energy performance. While white pigments consistently exhib-ited the lowest energy consumption across all climate zones, thermo-chromic pigments showed adaptive potential, particularly when their transition temperature and color phase contrast were optimized. Lowering the transition temperature and increasing the color contrast significantly reduced energy consumption and outperformed white pigments in Buda-pest and Oslo. The study suggests that selecting the appropriate transition temperature and increasing color phase contrast could improve energy efficiency, especially in climates with seasonal variations. Future re-search should focus on enhancing these properties and increasing the du-rability of thermochromic pigments to maximize their potential for use in energy-efficient buildings.