Dr. Oliver Kinnane:

Hemp is being used at a quite a low scale at the moment. Part L of the building regulations focuses on decreasing the U-value to very low levels, which makes hempcrete an outlier as a material because to reach the required U-value one needs between 600 mm and 700 mm thick walls, which is only practical in detached once-off rural developments. There could be more space in the building regulations for a whole-life carbon evaluation of these kinds of materials, not just their potential operational thermal resistance. They cannot be compared with polyisocyanurate, PIR, insulation, phenolic foam insulation or polymer-based insulation products in operation but they have very good thermal mass qualities to store heat and operate quite differently. A proper whole-life carbon analysis of hemp would show its potential and that should be enabled within the regulations.

The use of hemp should be incentivised. Certainly, hemp-wool insulation products are comparable with rock-wool and mineral-wool products in its thermal conductivity. There is plenty of scope for using that. The problem is that the product is more expensive because it is more of a niche ecological-based product.