Australian Hemp Masonry hempmasonry.com.au

Hemp lime construction and carbon storage

Low energy, high biomass, renewable building materials

AHM hemp lime building materials R & D

• 1999 - 2016 Licensed agronomic research

• UNSW 2000 – 2006 Development of multiple hemp-lime composite materials using whole stem and processed hemp hurd.

• Focus on LCA – our goal was to reduce the materials intensity of hemp lime construction i.e. encourage Australian regional production of hemp – minimise the amount of mined materials in the binder – manufacture in Australia – source binder materials in Australia – minimise packaging – minimise freight

• Ongoing research including in a number of climate zones 2006 – 2015 related to thermal performance and curing conditions

• 41 builds (incl 8 retrofits) plus 1 public building in Singapore)

• Shepherds Ground eco-village, Hunter Valley (commencing February 2016)

• Sustainable co-housing, Denmark WA• Health retreat, Uki

• AHMC has fibre industry partnerships in NSW, Victoria, WA. Our hope is to work with farmers to support the development of regional fibre industries in each state and with them, to have a major and positive impact on carbon management.

• Commenced discussions with Low carbon futures CRC

Proceedings of the 1st International Conference on Zero Carbon Buildings Today and in the Future, Birmingham City University, 11-12 September

2014.

“We believe that hemcrete has considerable potential for transforming the UK construction industry. The stable internal temperature and relative humidity lead to reduced reliance on mechanical systems, and to their lower installation and running costs. The stability of internal conditions has a considerable positive influence on thermal comfort.

The negative embodied carbon facilitates substantial long-term carbon emissions savings and goes a long way towards achieving the future UK carbon emissions targets.

Overall, we need more projects like this... ”

Social Housing – The Triangle, Swindon UK

43 Hemp lime homes with community gardens

UK Renewable House Monitoring Project Report, April 2015

2009 -10 UK Government’s Low Carbon Investment Fund (LCIF) invested £6.3m to support construction of 283 low carbon affordable homes built with a range of innovative, highly insulating, renewable materials.

Subsequently they funded of 2 year monitoring project:“the insulating properties of hemcrete mean that heating plant can be reduced in size, reducing corresponding energy consumption and carbon emissions, which could be in the range between 50% and 80% lower than in buildings with conventional brick and block construction insulated to the same U-value as the hemcrete construction.

The lower energy demand in-use, combined with the negative embodied carbon footprint (carbon sequestration potential) of the hemcrete structure at - 4.3 tonnes CO2 (compared with +10.7 tonnes CO2 for brick- block house of same dimensions)”

Life Cycle Analysis and building materials –what needs to be considered?

• The feedstock - farming including soil preparation, fertiliser use, harvesting and processing

• Freight

• Quantity and binder materials

• Production/manufacture of building material

• Waste

•End of life or recyclability

•Performance – energy efficiency

•Performance – air quality and health

•Durability of materials

•Comparison with impacts of other materials

.

300 year old hemp building, Miasa Mura Japanese National Trust.

Why hemp?Victorian Hemp Crop

Industrial hemp fibre crop at 2 weeks – the fastest growing biomass and the longest and strongest fibre plant available to humans

Ashford, Central Western NSW

4 – 5m plants, minimal irrigation (1/3 water compared to lucerne), sustainably farmed (pigs free ranged the site prior to planting)

Dungog, NSW Hunter ValleyDungog Growers Group formed and Dungog Mill established 2015

Minimum planting rate for fibre is 40 Kg seed minimum per hectare to encourage growth of branchless woody stems rather than leaf

What the fibre farmer is producingPartially processed industrial hemp fibre

Bast fibre (outer) and hemp hurd (woody core)

Processed hemp hurd used for construction of walls and for insulation

Material needs to be dust free, dry and bast should be removed.

Carbon storage in Hemp lime buildings

48 sq m cabin (walls only) approx 2 – 2.5 tonnes hemp hurd With roofing / subfloor insulation approx 4 tonnes

Larger home 6 plus tonnes hurd

Marks and Spencer (world’s first carbon neutral retailer) 210,000ft2 building saving 360 tonnes of emissions

•Carbonation – a slow curing process involving carbon being drawn on an ongoing basis from the atmosphere.

•Full carbonation process thought to be approx 50 years

Soil carbon, remediation and soil improvement

UK research indicates1 tonne soil carbon is added per hectare from:a) continuous leaf dropb) long taprootc) stubble

Highly suited to organic agriculture

Significantly less “ecotoxic” across 26 criteria in comparison to many other major crops (http://www.hort.purdue.edu/newcrop/ncnu02/v5-284.html)

Belgian Nuclear Research Centre findings: Hemp and flax recommended for remediation of irradiated soils (http://www.sciencedirect.com/science/article/ pii/S0265931X05000160)

Polish Agricultural University, Poznan: Removal of heavy metals from anaerobic sewage sludge (http://www.pjoes.com/pdf/12.6/779-784.pdf)

Small, E. and D. Marcus. 2002. Hemp : A new crop with new uses for North America. p. 284–326. In: J. Janick and A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press, Alexandria, VA.

http://www.hort.purdue.edu/newcrop/ncnu02/v5-284.html

Why how it is farmed matters …

Assessment of 1 tonne of hemp fibre cultivated in Europe and moved 300km to the factory gate to a non-woven producer in Germany demonstrated that in the production of hemp, the highest footprint in the cradle to cradle analysis is from mineral fertiliser use (835 co2-equiv Kg/tonne) compared to use of organic fertilisers (682 co2-equiv Kg/tonne).

Carbon Footprint and Sustainability of Different Natural Fibres for Biocomposites and Insulation Material (Nova Institut, 2015) www.bio-based.eu

• Industrial hemp - one of the most effective carbon sequestering plants. Locking up more than 15000kg of CO2 per hectare in just 90 – 100 days

The stems, particularly the hurd store the bulk of the carbon. This can be permanently locked up in building materials

Industrial hemp’s biomass

Europe

Information based on data from the three major

French producers (LCDA,PDM industrie and Eurochanvre)

•Each tonne of hemp produces 60% shiv or hurd,

25-30% bast and 10%-15% fines and dust.

•Av production is 8-10 tonnes per ha

•Carbon dioxide or carbon uptake required to

create one kilogram of dry material is equal to 1.7

kg of CO2.

Sylvie Pr‘etot, Florence Collet, Charles Garnier, Life cycle Assessment of Hemp Concrete Wall : Impact of Thickness and Coating. Building and Environment, Elsevier, 2014, 72C, pp.223-231.

Australian variations

•Av production is 12-15 tonnes per ha (different cultivars used in Australia for fibre production producing greater biomass)

•Tertiary treated effluent irrigated crops have given yields of 22 tonnes per ha

•Dryland crops equal EU production rates

•Exceptionally hardy crop

Potential carbon sequestration of hemp biomass (based on 1.7 carbon equiv kgs per kg of Hemp)

Europe

•Yield 8 -10 tonnes per ha

•1.7kgs x 8,000 = 13,600 Kgs or 13.6 tonnes per ha

•1.7kgs x 10,000 = 17,000 kgs or 17 tonnes per ha

Australia

•Yield 12-15 tonnes per ha

•1.7kgs x 12,000 = 20,400 kgs or 20.4 tonnes per ha

•1.7kgs x 15,000 = 25,500 kgs or 25.5 tonnes

Adnam’s Brewery and Distribution Centre2400 sqm Hemp lime building with sebum roof. 500mm thick hemp walls. Requires no refrigeration.

Temperature constant at 12 to 13 degrees C. 50 tonnes of carbon captured in the building

Comparative assessment of hemp processing for insulation matting and biocomposites with other currently used materials.

Hemp lime and the Binders

• Globally the majority of available binders for hemcrete are lime based.

• Depending on the country of origin the lime is hydraulic or hydrated.

• Most are produced in the England, Ireland and France.

• AHMC produces a lime-based Binder in Sydney

• Hydraulic lime, available in Europe is sourced from the edge of lime fields and contains other minerals in varying quantities. Dependent on the materials in the lime it is heated to temperatures between 900C and 1400C.

• Hydrated lime is available on all the major continents in the world and on some islands. It is heated to 900C.

Hemp lime building materials

High volumes of carbon lightly coated with a lime Binder. A low embodied energy masonry material.

Performance characteristics of Hemp lime materials

• High volume use of a readily renewable resource

• Low embodied energy

• Excellent thermal performance – slow phase change material

• Mitigates humidity well

• Excellent acoustic performance

• Breathable walls

• Does not encourage mould growth

• High flexural strength

• Zero waste

• Non combustible

• Lighter than most masonry materials

• Airtight construction

• Can be retrofitted –combines well with other materials

• Used in historic buildings to manage problems with moisture in walls

• Recyclable and reusable

• Performs as an effective carbon sink

• Easy building skill to transfer – socially beneficial

Thermal buffering

Award winning large objects store for London Science Museum

Hemp installed to mitigate humidity that detrimentally affects metal objects and archival materials

How is thermal performance achieved?

Monolithic construction – the frame is embedded – gives excellent airtightness

Highly insulative materialSlow phase change materialThermal inertia – it performs as a light thermal mass. Walls built

with hemp and lime absorb heat slowly from the air. The slow heat penetration means that air in a room will rapidly heat up to a comfortable temperature for occupation, similarly to a lightweight building. (In a heavyweight building this does not happen since the heat transfers rapidly into the thermal mass of the building, causing a slow heat-up response.)

It never gets cold to the touch – adds to the feeling of comfort i.e. thermal neutrality

The breathability of the material mitigates humidity – it has excellent thermal conductivity

Thermal value (R value) achieved

Thickness mm of roofing and subfloor insulaaion

100mm

150mm

200mm

250mm

300mm

R (m2 KW-1) 2 3 4 5 6

Thickness mm of walling materials

100mm

150mm

200mm

250mm

300mm

400mm

R (m2 KW-1)

1.4 2.10 2.85 3.55 4.25 5.0

Hemp lime construction in Australia

Most common current use – external walling at min 200mm hemp-lime or lime rendered externally, sometimes rendered internally (often sealed with a breathable sealant).

Internal walling min 150mm thick

Most architects are designing for 250mm wall thickness

Design opportunities - Two storey studio, Victoria

1 sq m ‘truth’ windowLime rendered hemp lime

walls

CDL Green Gallery and Heritage Museum

Singapore Botanic Gardens Australian Hemp lime materials and living walls

UNESCO World Heritage listed

Modular steel construction, exposed hemp walls

The hemp wall is supported on an L beam and tied into the steel with

purlins

Textured finish using weatherboard formwork. Colour variations using mineral oxides and coloured sands

Clay render, Starseed Nursery Byron Bay

Mullumbimby – small 2 bedroom home with adjoining guest accommodation.

Owner built cottageBateman’s Bay, NSW

Owner Build Tintenbar, Northern Rivers NSW 6m x 8m (6 days – 2 of formwork, 4 of installing)

Hazelbrook, NSW Blue Mtns

Deep Ecology Centre, Maclean

Internal walls unrendered other than around windows and doors

Material lends itself to creating nooks

Retrofit - Deep Ecology Centre, Maclean NSW

Internal walls are unrendered other than around windows and doors

Retrofit Canberra40mm thick uninsulated gyprock walls replaced with 120mm hemp

lime for acoustic and thermal insulation.

Feedback from Australian home owners:

"So far the thermal performance has been great. We’ve had quite warm days over summer with only occasional ceiling fan use being enough to keep comfortable. We haven’t been through the whole winter yet, but have had nights around 6 degrees.The gas hydronic controlled underfloor heating is set to 16 degrees and never comes on at that temp.We sometimes set the kids’ room to about 20 degrees, and it comes on occasionally in the night. " (Home owners, Hazelbrook, Blue Mtns, NSW)

"When you enter the home you can instantly experience how the hemp keeps the home cool. This past Northern Rivers summer there were plenty of 40 C plus days and because there have also been rains, the humidity has been peaking, so a building made from a breathable material that mitigates humidity is ideal." (Home owners, Mullumbimby, NSW)

Factors that can negatively affect potential thermal performance in hemp lime buildings:

Design: the existence of unsealed service voids behind plaster boards that caused considerable air leaks through sockets

Workmanship: in some of the UK buildings larger than needed holes

were drilled for cables and pipes and were left unsealed; in some instances poor mixing and over-compaction of mixes meant installation wasn’t uniform. (They did not enough trained installers to do a large project so the findings emphasised the need for more training.)

The quality of building components: there was evidence of considerable leaks through patio doors and loft hatches

Forming up fully on one side

Using formply or permanent breathable formwork such as MgO board, weatherboards

Roofing insulation in a pitched roof

Hemp and Binder mix without sand, raked in and lightly

tamped

Hemp lime subfloor and roofing insulation, Tradesnorth workshop, Perth

Hemp ceiling insulation

Hemp floors in the UK

Subfloor insulation or floors slabs

finished with a sand lime screed.

Centre of Alternative Technology, Wales  2009

Dry-lining versus a hemp and lime insulating render for internal thermal renovation of a stone cottage in West Wales

" The conditions present in the cottage hemp/lime project at CAT are possibly some of the harshest that might be encountered in the United Kingdom for internal insulation of a solid wall. Even in this harsh environment the hemp lime can be effective at reducing moisture load in the wall.

Dry Lining causes moisture to accumulate in the wall and space behind it which will lead to rot, internal structural damage and increased frost damage.

Hemp renders are not only insulating but also dry out the external wall and handle moisture well, suggestive that they reduce the risk of rot, mould and frost damage overtime.

Although from the monitoring it is impossible to discern if the hemp render will dry out the adjacent wall this did occur in three separate WUFI models under differing conditions.

This is therefore indicative that the Hemp render will actively dry out an underlying wall”

Ensuring optimal performance in hemp lime construction

• Do not build when the temperature will not get above 5 degrees celsius

• Materials must be dry• Managing the moisture in the mix and in the build.• Hemp lime should not be used below ground• Ensure good site drainage and that window sills allow water to

runoff• Avoid narrow wall sections & small isolated sections• Minimise timber where possible – 1300 noggin, angled noggins

Ensuring optimal performance

• Framing – minimise the timber or steel wherever possible• Protect steel, protect aluminium windows and glass• Ensuring a min of 50mm in front of studs• Use permanent formwork around windows and doors• Fixings and fixtures– stainless steel or galvanised screws are

recommended where they are in the hemp lime, use conduit, fix heavy cupboards to the frame,

• Do not build with the roof off• Careful curing and finishing no earlier than after 4 weeks

Curing cont.

Walls should be protected from extreme winds, rain, and intense direct sunlight in summer for at least week

Material needs to carbonate

rather than dry

Needs air circulation for curing

Freshly laid material is green when forms are first removed and up to 1 week – avoid any knocks

Thank you for your interest!

Klara Marosszeky

klara@hempmasonry.com.auwww.hempmasonry.com.au