The hygrothermal refurbishment of old building envelopes is becoming a challenge because of the specific behavior of such systems. Common, commercially available solutions do not meet all the requirements, as they could affect the durability of materials but bio-based solutions could be interesting. Bio-based solutions appear to be an appropriate and a sustainable insulation for historical dwellings. In this chapter, we investigate both the laboratory and on-site behavior of some solutions and address their complexity. The on-site measurements also allow summer comfort and phase shift phenomena to be explored.
