In 2018, 117 Mt of CO₂ emissions in Germany originated from the building sector. This corresponds to 14% of the total greenhouse gas emissions in Germany. The climate goals cannot be achieved with the current rate of energy refurbishment.
Despite a variety of current insulation concepts, different properties of the materials used, which go beyond the primary goal of insulation, are often inadequate or problematic. In addition, a payback of the investment through savings in energy costs is not feasible in all cases.
This contribution examines a micro hollow glass sphere-based interior and exterior insulation as an alternative to existing thermal insulation composite systems, which is characterised by a special combination of open and closed pores. The so-called ecosphere system is a cement-based sprayable insulation material with a volume fraction of approximately 90% micro hollow glass beads (glass bubbles). Glass bubbles are thin-walled (0.3-2.0 µm) spherical glass particles with a diameter of 30-200 µm (see fig. 1, left). For decades glass bubbles are an important product in niche markets. With this new application, the bubbles will enter the mass market.
The processing technology is of crucial importance for the outstanding properties of the insulation. By improving existing spraying technologies for plasters it is now possible to apply this composite material to façades with a thickness of 15 cm without damaging the filigree glass bubbles. The compressed air-driven spraying process introduces additional porosity into the insulation, and thus further reduces thermal conductivity. Because of the high amount of porosity (93%), the glass bubble insulation has a density of just 125 kg/m3 and thermal conductivity of 0.040 W/mK. Moreover, because ecosphere is a purely mineral insulation material, it can be reused at the end of its life cycle as an aggregate for hydraulically binding building materials after crushing and moderate heat treatment.