## 1 Introduction  
One solution to meet the global growth in energy demand is wider utilization of solar energy. This is one of the most challenging environmental ambitions influencing numerous industries, including building and construction [1]. Attention has focused on the development of various solar cells (thermal, photovoltaic, etc.) and collectors. One of the promising fields in this regard is the development of facade systems that integrate passive or active heating and cooling [2,3]. Such systems can increase the energy efficiency of buildings and help them achieve near-zero or even zero-energy performance levels. However, their successful integration requires finding synergy between thermal insulation of the facade in cooler periods and overheating in warmer periods. Ongoing research projects, such as [4, 5, 6], strive to improve energy performance of buildings using solar heating and/or cooling. 6. Potential innovations include materials with reflective [7, 8], solar [9, 10], and selective [11] parameters able to work within a particular range of the thermal radiation spectrum. Research presented in the current study also contributes to this field. In this study, we developed a novel selective absorber technology for potential building integration that can prevent heat losses,influence overheating, and allow environmentally friendly conversion of incident solar energy into thermal energy [12]. Commercially available solar selective coatings applied in solar absorbers are produced from non-renewable resources (such as oil), whose reserves are declining due to increasing demand. This issue, combined with energy-intensive production (which also releases considerable greenhouse gas emissions) and questionable recyclability, are disadvantages of the use of these materials for sustainable construction. Furthermore, these issues have motivated researchers to identify new, renewable, and more environmentally friendly resources. Expensive high-tech technologies exist, such as the production of nanostructures. In addition, low-tech and low-cost polymeric photonic technologies appear to present a viable option for the present and the near future [13]. Therefore, it is desirable to develop a coating with high structural stability (with dependable production processes) to reduce the cost and environmental impact of solar absorbers, [14]. Another characteristic of many solar absorbers, such as the stable cermets of conductive ceramics TiN in SiO\({}_{2}\)[15], is that they are designed for operating temperatures of 300 \({}^{\circ}\)C and higher [16]. Such temperatures are appropriate for solar thermal systems [17; 18; 19]. However, it has been also shown [20] that a suitable design of an absorber system integrated in a building facade can reach a maximum temperature of approx. 80 \({}^{\circ}\)C. This enables the use of less demanding (and expensive) materials, such as polymers, for the production of absorbers, resulting in notable economic and environmental benefits. Overall, polymer-based products are likely to be commonly used in the future due to their significant advantage over other non-polymer nanophotonic materials in terms of manufacturability and cost [21]. The key attributes for the newly developed solar absorber material described in this paper are therefore low cost; high absorption of solar radiation (\(\alpha_{\mathrm{s}}>0.9\)); medium emissivity (\(\varepsilon<0.4\)); high durability in the context of long-term operating temperature of at least 80 \({}^{\circ}\)C; low environmental impacts; easy applicability to common building surfaces; and production with readily available industrial technologies (in the context of developed or developing regions, such as Central Europe). Recent development of solar selective absorbers highlights the need for cost-effective and environmentally friendly materials with high selectivity and durability [22]. Both of these parameters heavily depend on efficient resource consumption (energy, materials, etc.).