An initial report into thermal performance of hemp and lime wall sections in the wise building at CAT

Hemp and binder (e.g. Lime) is an insulating wall matrix formed around a timber
frame. It has multiple environmental benefits including sequestering carbon dioxide from the
atmosphere into a building‟s walls and is thus of interest in the current climate situation.
However the thermal performance of the matrix when evaluated using the steady state
thermal conductivity (i.e. rate of heat transfer) is not as effective for the same thickness as
other insulations. The world however is dynamic and in the Haverhill Housing Project
monitored by the Building Research Establishment (UK) two hemp and lime houses, despite
having a worse steady state thermal performance on paper, significantly outperformed
comparative standard houses (BRE 2002, 2003).
The reasons for this unexpected performance are not clarified although the heat storage
capacity and the moisture handling ability of the matrix are possibilit ies. Hemp and binder
matrix has been shown to have considerable moisture handling and heat storage capabilities
but how or whether these improve thermal performance is not clear. All the tests reported so
far have been on the same binder yet there are many potential binders and each will change
the properties of the matrix and each has a different environmental legacy.
To further clarify the in-building performance and to compare a range of binders, 5 different
binder test wall sections in the Welsh Institute of Sustainable Education building at the
Centre of Alternative Technology are being extensively monitored for heat flux, temperature
and moisture movements. This paper is an initial report of this experiment.

Citation:
Rhydwen, R., Tucker, S., Butler, A. and Wijesekera, C., (2011)"An initial report into thermal performance of hemp and lime wall sections in the wise building at CAT" Advances in Computing and Technology, University of East London, January 2011, 52-59.