EMPA

The Swiss Federal Laboratories for Materials Science and Technology (EMPA) is a multidisciplinary research institute with 142 years of history behind it. First starting as the “Building Materials Testing Institute” in the cellars of Zurich’s Federal Polytechnical School (now ETH Zurich) in 1880. It is a part of the ETH Domain, a federal entity managing the two Swiss Institutes of Technology and four federal laboratories.

We met with Dr. Ivan Lunati, the head of the Laboratory of Multiscale Studies in Building Physics, and Dr. Wim Malfait, the head of the Laboratory for Building Energy Materials and Components. In addition to consulting their expertise in Aerogels and Building Physics, we engaged them as scientists-stakeholders, and as stakeholders in aerogel applications.

For the scientific interests, we have confirmed that scientists and researchers are also stakeholders themselves. A material science research must have a promising application to be pursued, and ideally bring visibility to the laboratory in question. Additional functionalisation of materials is also an important area of interest. Yet, we saw that the interest of scientists in this field also led to ambiguities. The question of what constitutes a cellulose aerogel is an ongoing debate in the material science field, as some researchers include macroporous cellulose foams to the classification of aerogels while others strictly consider nanoporous and transparent cellulose composites as aerogels. This division is reflected in the scientific literature, as many papers on cellulose aerogels using different techniques end up producing vastly different materials.

Within the industrial scale production, we learnt that 20% of all industrial production of aerogel based insulation materials were dedicated to building insulation, and 25-50% of this margin is found in Switzerland. Indeed, Switzerland is a pioneer in aerogel application, tying our project more into the local interests. For the production techniques, we learnt that silica aerogels (the most prominent type of aerogel) are produced in mass by being embedded in insulative sheets and critical-point-dried as such, with the aerogel forming inside the sheets. The resulting material has a lambda value between that of the silica aerogel and the insulative sheet, resulting in a compromise between peak performance and ease of application. The resulting material is still a high-performing one, albeit quite energy intensive in the critical-point-drying step.

Dr. Malfait then gave us an example: An aerogel based material (Fixit 222) was developed in cooperation with EMPA in 2013, with a lambda value of 0.028 W/mK, enabling high-performance with record thinness. Nowadays it has been commercialised, available for sale and widely used. High-performing materials contribute to energy efficiency with minimal material applied, thus saving energy in both production AND heating.

Cellulose aerogels are currently far from an industrial approach, yet the interest is there. We were made to understand that for any new aerogel application to be seriously considered, the lambda value has to be below 0.020 W/mK, as the peak performance of silica aerogels is around 0.015 W/mK. Recent research shows results for cellulose aerogel reaching this performance, yet it is not far from conclusive.

If the necessary performance can be achieved with the same efficiency in production, then cellulose aerogel is a more viable option. Silica as a raw material is expensive while cellulose is cheap and abundant. Using cellulose is also more ecological, and doesn’t have biodegradability or accumulation concerns.

Overall, our visit to EMPA led us to rethink our production phase, gave us the pillars for our proposed implementation objectives and understand the stance of scientists as stakeholders.