Hemp in construction - The Hempcrete Topic: Designing and Building with Hemp-lime - page 37

Panels being made at the factory. Image: Lime Technology Ltd

The panels are air-dried at the manufacturing plant, which involves blowing air through
them to achieve faster drying, and during the winter this air may be heated. Taken together
with the increased use of mechanized processes and transportation, there is some doubt
that pre-cast panels can claim the same level of environmental credentials as cast-in-situ
hempcrete, and they are arguably less sustainable than blocks because of the additional
processed materials they include. However, Lime Technology's literature confirms that the
panel systems are carbon negative in terms of their embodied energy.

The predictable nature of pre-cast panels, together with their availability in bespoke
sizes to fit the building design, is attractive, especially for large-scale commercial builds.
While the complexity of panel systems makes them inherently more vulnerable to thermal
bridging and poor airtightness compared with cast-in-situ hempcrete - perhaps even more
so than with blocks - if the design of the panels is sufficiently robust, these issues can
be overcome through detailing and the addition of extra materials into the wall build-up.
The published values for thermal bridging and airtightness achieved by Hembuild ® and

Hemclad ®

are certainly a demonstration of this. Unfortunately, however, the solution of