APPLICATION OF HEMP-LIME RENDERS TO IMPROVE INSULATION OF WALLS.

Author(s): J. McGinn, S. Pavia, O. Kinnane
Paper category: Proceedings
Book title: Proceedings of the 3rd International Conference on Bio-Based Building Materials ICBBM 2019
Editor(s): Mohammed SONEBI and Sofiane AMZIANE
ISBN:
e-ISBN: 978-2-35158-229-9
Publisher: RILEM Publications SARL
Publication year: 2019
Pages: 702 - 707
Total Pages: 6
Language: English

Abstract: This paper measures the variation of thermal transmittance of solid brick walls triggered by the
application of hemp-lime renders in an effort to enhance the insulating properties of buildings. Six
renders with different proportions of hemp and lime were fabricated and two selected based on
their workability and adhesion. They were applied to the walls and their thermal transmittance
measured using the hot box method. Thermal imaging was used to control thermal bridges in the
masonry assemblies. When compared to commercial mixes such diathomite and expanded
polystyrene, the hemp-lime renders display similar thermal properties that qualify them as good
insulators. It was evidenced that the application of a hemp-lime render can halve the thermal
transmittance of a solid brick wall. The renders notably increased the resistance to heat transfer
of the brick wall. Render 5 [a 1.25: 1 - hemp: NHL3.5 mix applied in a 21 mm depth] nearly doubles
the thermal resistance and halves the thermal transmittance of the wall, reducing the U-value from
6.99 to 3.65 W/m2K therefore doubling the insulation provided by the solid brick wall.
It was also noted that the 21 mm hemp-lime renders improved the thermal properties of stone
walls, but the improvement is not as notable as in the brick walls. However, a thicker render [40
mm] would greatly improve the thermal performance of the stone walls reducing U-values by
c.40%.
The outstanding insulating ability of air gaps was exposed when the hemp-lime renders were
applied on a metal lath/mesh set with a 20 mm gap off the wall: here, the U-values lowered by
over 30%. Also, it was demonstrated that the hemp-lime renders improve the thermal performance
of solid walls to a much greater extent than cavity walls.

Online publication: 2019
Publication type: full_text
Public price (Euros): 0.00