The EN-standard 13167 is rather clear about cellular glass for building applications. The water vapor diffusion resistance µ should be larger than 40000. This property has to be measured according to the standard EN 12086, which has its last version in 2013. The reason for this large µ-value is rather clear. Cellular glass has the reputation to eliminate perfectly internal condensation thanks to this very large µ-value.
However, there are two reasons to doubt and review the above story in the building , namely two practical ones and a bureaucratic one.
- The bureaucratic one is that the standard EN-12086 from 2013 contains an error on page11. Indeed, the mentioned gas constant of water vapor is a factor 100 too small, which means that a cellular glass with a real µ-value of 400 is allowed by the (erroneous) standard. A µ-value = 400 is an open cell cellular glass. This means that today open cell cellular glass is covered by the EN13167 standard.
- The practical one is that an open cell cellular glass has an improved acoustical absorption with thermal conductivity 0.056 W/mK. This material can be used between two thin sound reflecting materials to obtain a light sandwich with a small sound transmission. Another application is simply to use it to reduce echo (reverberation) without using combustible material.
- Another use op open cell cellular glass can be find in the hydro-culture world, like already mentioned in a previous post. But I can imagine it makes also sense to let grow plants against this material vertically installed inside and outside. The material serves as plant growth medium, thermal insulation and acoustic absorb-er.
In our opinion, it is clear that the EN-standard 13167 should be rewritten to allow non-combustible (cellular glass) thermal insulation with a high compressive strength and interesting acoustic properties. We should simply specify a minimum µ-value and maybe even a maximum µ-value. Today, it seems hard to sell cellular glass thermal insulation with important acoustic absorption within the EN- standards system because only cellular glass with µ-value > 40000 is allowed for building applications.