The energy efficiency of buildings can be greatly improved by decreasing the energy embodied in installed materials. In this contribution, we investigated the possibility of foaming waste bottle glass in the air atmosphere with the addition of water glass, which would reduce the energy used in the production of foamed glass boards. The results show that with the increased addition of water glass, the crystallinity and the thermal conductivity decrease, however, the remaining crystal content prevents the formation of closed-porous foams. The added water glass only partly protects the carbon from premature oxidation, and the foaming mechanism in the air is different than in the argon atmosphere. The lowest obtained foam density in the air atmosphere is 123 kg m⁻³, while the lowest thermal conductivity is 53 mW m⁻¹ K⁻¹, with an open porosity of 50% for the sample obtained in the air, containing 12 wt% of water glass, 2 wt% of B₂O₃, 2 wt% AlPO₄ and 2 wt% K₃PO₄.

Saving natural resources such as sand and clay, and decreasing energy input, thereby reducing CO2 emissions, are crucial for a sustainable production of construction materials. Recycling and reusing waste materials in green building materials are effective and reduce the environmental burden of waste materials. In our study, we achieved two key objectives: (1) recycling glass fiber–reinforced plastic (GFRP) from decommissioned wind turbine blades, and (2) producing fired clay bricks at reduced temperatures. Our results demonstrate that adding up to 40 wt% GFRP is feasible, and that the firing temperature can be lowered to 800°C, while maintaining acceptable brick properties compared to bricks fired at 1000°C. Increasing GFRP content allows for a lower firing temperature of the produced bricks, but also reduces the brick density and, consequently, the thermal diffusivity and flexural strength. The resulting bricks are anticipated to be suitable for low-load applications in buildings.