Thermal insulation
1. Background and state-of-the-art (SotA)
Despite climate change denial, global climate data show rapid warming of the planet. Efficient use of energy and raw materials at all stages is key to reducing CO2 emissions and combating rising temperatures [1]. 45–50 % of total EU energy consumption is related to buildings and EU efforts are directed towards reducing the greenhouse gas emissions of the building sector by 60 % until 2050 [2]. Decarbonization of the building sector can be achieved by improving the thermal insulation materials and the energy efficiency of their production.
New materials [3] with outstanding insulation properties emerging in state-of-the-art lack mechanical performance, energy and resource efficiency, and/or production feasibility. Our research focuses on improving the properties and preparation processes of conventional materials, as well as developing new hybrid processes and composites. The goal is to create materials and processes with good production feasibility within a short timeframe, for which we collaborate with research and industrial partners.
Figure 1: One of the concepts of developing a sustainable thermal insulation material based on problematic waste.
2. Objectives, originality, and impact on new research approaches
The objective of the research is to improve the properties and production processes of thermal insulation materials to contribute to efficient energy use, decarbonization, and the circular economy. In the field of foam glass, our unique approach is to study foaming mechanisms, a complex compilation of reactions occurring during foaming that alter the physical and chemical properties of the material [4,5]. This knowledge helps identify opportunities to enhance the properties or design new preparation processes with better energy efficiency and circularity (e.g., recycling various waste materials, improving insulation performance, foaming in an air atmosphere).
We have been developing mineral wool products with a focus on understanding the processes occurring in the material at high temperatures [6]. With our state-of-the-art equipment, we investigate structure–property relationships in the materials. This knowledge allows us to determine the reasons for observed problems or inconsistencies, as well as to adjust the process or design new methods for creating products with improved characteristics. Our work targets enhancing high-temperature stability, fire performance, thermal insulation properties, mechanical properties, hydrophobicity, and durability.
For organic insulation, we focused on a new recycling method by developing new fire-resistant EPS with an advanced blend of non-toxic fire retardants and a structure that provides superior fire resistance. Organic insulation foams have a high CO2 footprint, which can be reduced through smart recycling into high-value products. While packaging organic foams do not contain fire retardants, organic foams used in construction include potentially toxic additives. The new fire-retardant coating formulation will allow both waste streams to be utilized in producing a product with superior fire performance. Moreover, it will reduce the dependence of local producers on multinational chemical corporations.
Furthermore, we contribute to developing i) new construction solutions that incorporate improved insulation materials [7], ii) new materials for specific applications, iii) prolonged lifespan of materials and products, iv) new low-temperature processing for clays as one of the key construction materials [8], and v) recycling of secondary raw materials in clay bricks production [9]. The materials we develop are largely recyclable, and the processes enable green, large-scale production.
Close collaboration with leading industrial players in the field of thermal insulation materials guarantees the development of new materials and technologies that are industrially feasible. The products with improved properties and production technologies are less energy demanding, which provides a competitive advantage to our industrial partners. The collaborative research strengthens the position of the industrial partners on the market, secures and expands the workplaces and profits.
Figure 2: Developing a waste-based insulation material by utilizing an appropriate heat transfer model, analyzing optimal processing temperatures, implementing suitable reactions, and optimizing the process towards highly porous structures with closed porosity.
3. Unique methodology
Our approach is based on analyzing and studying the underlying reactions and mechanisms occurring during the synthesis, thermal treatment, and aging of the materials and products. In addition to standard characterization techniques like X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and thermal analysis (TA), we employ mass spectroscopy (MS) and gas chromatography (GC) to analyze the gases released from the heat-treated sample and foamed sample, respectively. Through X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM), we precisely monitor the migration of atoms and identify the newly occurring phases. Raman and IR spectroscopies are used to identify even the smallest changes in the structure and presence of organic contaminants. By continuously adapting and customizing our approaches, we can develop methodologies that are specifically tailored to the unique requirements of materials or process-related challenges. This flexibility allows improved precision and enables us to lead state of the art research across various fields.
Figure 3: Our approach to the development of new processes and products.
REFERENCES:
1 EU Commission, Energy Efficiency Directive, 2012
2 EPBD, Directive (EU) 2024/1275 of the European Parliament and of the Council of 24 April 2024 on the energy performance of buildings, Official Journal of the European Union 1–68 (2024)
3 Jelle, 2011, Traditional, state-of-the-art and future thermal building insulation materials and solutions – Properties, requirements and possibilities
4 a) J. König, et al, Synthesis and properties of open- and closed-porous foamed glass with a low density, Constr. Build. Mater. 247 (2020) 118574;
b) Suppressing the effect of cullet composition on the formation and properties of foamed glass, Ceram. Int. 44 (2018) 11143–11150;
c) Evaluation of the contributions to the effective thermal conductivity of an open-porous-type foamed glass, Constr. Build. Mater. 214 (2019) 337–343
5 J. König, R.R. Petersen, Y.Z. Yue, A method to produce foam glasses, European Patent Office, EP2966044B1
6 a) J. König, Mineral wool composite with improved insulation properties, project Slovenian Research Agency, 2018-2021;
b) Development and characterisation of mineral wool fibers and binder systems, Knauf Insulation d.o.o.
7 Cleantech Block II - energy-saving cladding, EUDP Denmark (15-I64015-0018) 2015-2018
8 Applicability of the cold sintering process to clay minerals, ARIS (J1-3026), 2021-2025
9 Recycled materials integrated in bricks, supporting the circular economy in the construction industry – ReMaBrick, Innovation Fund Denmark, 2023-2026