**6. Conclusions**

Cellulose-based aerogels can have thermal conductivities as low as –0.015 W·m−1·K−<sup>1</sup> falling into the category of "super-insulating" materials. This range of thermal conductivities seems to be a consequence of an interplay between different factors, such as a non-interconnected porous morphology with an average pore size bellow 70 nm. Low density (<0.025 g·cm−3) is also required to decrease the contribution of heat conduction through the solid matrix. However, a continuous decrease in density will eventually lead to an increase in pore size beyond 70 nm, thereby increasing the thermal conduction of the porous solid.

The following topics could be drawn as points of interest for further development of cellulose aerogels as thermal insulators in buildings:


**Author Contributions:** Conceptualization, D.I.; Investigation, D.I. and J.M.; Resources, D.I. and J.M.; Writing-Original Draft Preparation, D.I. and J.M.; Writing-Review & Editing, D.I., J.M., H.M. and H.G.; Supervision, H.M. and H.G.; Project Administration, H.M. and H.G.

**Acknowledgments:** The authors would like to acknowledge the Universidad Del Norte and the Departamento Administrativo de Ciencia, Tecnología e Innovación (Colciencias) for the support given within the framework of the PhD National Scholarship Colciencias N◦ 617-2014 (Contract Identification Number UN-OJ-2014-26159 and UN-OJ-2014-24072).

**Conflicts of Interest:** The authors declare no conflicts of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
