Hemp lime concrete is a building material made from hemp shiv, hydrated lime, and water. It has low compressive strength but excellent thermal insulation and hygrothermal properties. These allow it to regulate humidity and provide thermal dampening better than traditional insulation materials. Additionally, hemp lime concrete is carbon negative over its lifetime. The document provides examples of renovation and new construction projects in France, the UK, and Belgium that utilize hemp lime concrete, ranging from single family homes to large industrial buildings. It concludes that hemp lime concrete is a growing building material with over 20 years of experience in France and potential for wider industrial application.

1. Hemp Lime Concrete (HLC)
A carbon-negative construction material
Didier Lesueur – Materials R&D Manager
GRD meeting – Limelette – April 6th 2011

2. Outline
• Hemp Lime Concrete
• Regulation and Application
• Practical Examples
• Conclusions
2

3. Outline
• Hemp Lime Concrete
• Regulation and Application
• Practical Examples
• Conclusions
3

4. What is Hemp Lime Concrete?
Aggregate
Binder
Hydrated
Lime
Hydraulic
Binder
Additives
& Admixtures
Dry Mix
Water
Hemp
Shiv
Hemp Lime
Concrete
4

5. Why lime?
• Hemp shiv has a
huge water demand
• Lime imparts good
water retention
• Hence a balanced
competition for
water
• Otherwise,
flouring risk with
purely hydraulic
binders
source: Y. Hustache, Synthèse des
Connaissances sur les mortiers et
bétons de chanvre, Lhoist/CenC, 2008
5

6. Different types of Hemp Lime Concrete
Roof
Wall
Screed
Render
With different binder concentration:
kg binder / m³
110
220
280
600
6

7. Hemp Lime Concrete
Relative Properties
• Low Compressive Strength
 Need load bearing structure
Concrete
SLB
Clay Bricks
AAC
HLC
0
5
10 15 20 25 30 35 40 45 50 55 60 65 70 75
Compressive strength (MPa)
7

8. Hemp Lime Concrete
Relative Properties
• Good thermal insulation performance
¬ 2-3 times thicker HLC layer than traditional insulation
¬ 10 times better than traditional cement concrete
0
0.026
0.07-0.11: HLC
λ thermal
conductivity
(W/m/K)
Perfect insulation
Air
0.04
Exp. PolyStyrene / Mineral Wool
0.1-0.2
AAC
0.3-0.5
Clay brick
1
Concrete
8

9. Hemp Lime Concrete
Relative Properties
• Thermal dampening better than expected from
static thermal conductivity
20
15
Outside
temperature
Wood +
insulation
10
5
Hemp Lime Concrete
47
43
39
35
31
27
23
19
15
11
0
7
U = 0.44
W/m2/K
Insulated
brick
3
source: A.
Evrard, Ph.
D. Thesis,
UCL, 2008
Aerated concrete
Inside wall temperature vs outside daily 0-20°C temperature cycle
Hours
9

10. Hemp Lime Concrete
Relative Properties
•
Unique hygrothermal
behaviour
• Allows humidity regulation
and good thermal
dampening
¬ Shiv / binder porosity
stores and releases
humidity
¬ Water sorption /
evaporation improves
thermal dampening
(Phase Change Material)
• Yields superior comfort
perception
10

11. Hemp Lime Concrete
Thermal Performance
Thermographic Images
source: I.
Mawditt,
Living
Space
Sciences,
2008
11
Tradical Hemcrete (2007)
®
®
Cavity Wall (1970’s)

12. Hemp Lime Concrete
Relative Characteristics
• Negative carbon-footprint
kg eq CO2
/m²/year
source: M.P. Boutin et
al., INRA,
2005
over 100
years
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
-0,2
-0,4
clay brick (monomur)
Aerated Concrete
Concrete + insulation
HLC
12

13. Outline
• Hemp Lime Concrete
• Regulation and Application
• Practical Examples
• Conclusions
13

14. Hemp Lime Concrete
Regulation
•
France
¬ Règles
professionnelles
•
UK
• BBA / LABC approved
•
Wallonia
• Entering the list of
accepted insulation
materials
14

15. Placed between shutters...
15

16. ... or sprayed
16

17. Shutters can be removed after 24 hours
17

18. Final render applied after ~ a month
18

19. Outline
• Hemp Lime Concrete
• Regulation and Application
• Practical Examples
• Conclusions
19

20. Hemp Lime Concrete
Used in all construction categories
Renovation
New
Single housing
Commercial
Multiple housing
Industrial
20

21. Renovation work
• Maison Diocésaine Odette
Prévost (2004)
¬
¬
¬
¬
Chalons-en-Champagne (F)
Architect: Atelier Méandre
Observ’ER Award 2006
« Insulation » of the stones walls
with an hemp plaster (5 to 7 cm)
21

22. New industrial building
• Adnams
Distribution
Center (2006)
¬ Southwold (UK)
¬ Architect:
Aukett Fitzroy
Robinson
¬ David Alsop
Sustainability
Award 2007
¬ No air cooling
system (400 000
£ saved)
22

23. New industrial building
• Wine Society (2009)
¬ Stevenage (UK)
¬ Architect: Vincent &
Gorbing
¬ 400,000 kWh of gas +
electricity saved each
year (compared to
project)
23

24. New industrial building
• Marks & Spencer (due 2011)
¬ Cheshire Oaks (UK)
¬ Architect: Aukett Fitzroy
Robinson
¬ M&S biggest store outside
London (14 000 m2)
24

25. New private or social housing
25

26. Outline
• Hemp Lime Concrete
• Regulation and Application
• Practical Examples
• Conclusions
26

27. Hemp Lime Concrete
Conclusion and Perspectives
•
Carbon-negative construction material
¬ Wall, floor and roof insulation
¬ Phase Change Material with dynamic thermal properties
better than predicted from static thermal conductivity
•
Growing number of projects
• 20 years of experience in France (> 10 000 references)
• 5 years of experience in the UK (> 250 references)
• Emerging in Belgium
• Project size is increasing (UK first, now France)
•
Technical challenges ahead
• How to take into account the PCM effect in buildings
thermal design?
• Reach industrial application rates (faster drying...)
27