Performance of hempcrete in a building - The Hempcrete Topic: Designing and Building with Hemp-lime - page 147

The thermal mass of hempcrete also makes it easy to maintain indoor air quality, because
the storage of heat in the fabric of the building allows for natural ventilation of the indoor
space by opening windows and doors, without concern that the heat in the building will be
quickly lost. For more on indoor air quality, see Chapter 4, page 65 ) .
A note on materials and workmanship
A common theme throughout the findings outlined in this chapter is the degree to which
different materials, mix ratios and application techniques, especially with regard to the
amount of compaction, affect the performance of hempcrete.
At the present time, while individual proprietary materials (Lhoist's Tradical ® Hemcrete ®
system) have been tested for Local Authority Building Control pre-approval (see Chapter
6, page 84 ) , the UK still lacks any industry-agreed standards or guidance, either for the
desired characteristics of hemp shiv and binders for making hempcrete, or for correct ap-
plication techniques.
As can be seen from the information in this chapter, hempcrete is a versatile material
whose performance can be adapted within a range of parameters, according to the require-
ments of the building design or the specific application. However, rather than being known
for this versatility in the UK, hempcrete is seen in some quarters as being unpredictable
and difficult to use. This says more about the current knowledge and skills of the UK con-
struction industry in this area than it does about the material itself.
It is true that a real issue with hempcrete currently is that the eventual thermal, acoustic
and mechanical performance of the material in the finished building is heavily dependent
on the knowledge and skills of the contractor, and that these are not always at the level re-
quired. Thus, variations in these aspects of the material's performance that are found from
building to building, far from being different by design, often occur quite randomly, owing
to contractors not really understanding the potential of the material or how this can be best
unlocked.
The development of recognized standards for materials and construction techniques would
not only assist the industry in regulating the standard of new hempcrete buildings in the
UK and providing a valuable 'Kitemark' for construction professionals using hempcrete,
but would also help to provide a more structured framework for continued research into
the performance of this remarkable material.