Plant based materials such as hemp can help to improve the sustainability of Australia’s public buildings, the head of a Melbourne based design firm says.

(above image: Powerhouse Place, Mildura. Image source: Public Realm Lab)

Speaking at the recent Hemp Connect forum held in Melbourne, Anna Maskiell, director and co-founder of Melbourne based design practice Public Realm Lab, shared her firm’s experience in advocating for the use of hemp on public building projects.

According to Maskiell, opportunities to deliver more sustainable buildings through use of hemp are significant.

“Our current methods for designing and delivering built environments for humans is not quite so sustainable,” Maskiell said.

“For us as a practice, we think that mainstreaming hemp in construction is critical to rapidly turning this around.”

(Powerhouse Place, Mildura. Image source: Public Realm Lab)

The push for hemp

The comments come as Australia’s hemp industry is trying to increase the penetration of products which contain hemp across the nation’s building sector.

As mentioned in a previous article, hemp as used in industrial processes is a variety of the Cannabis sativa plant which is cultivated for fibre and seeds.

It is distinct from marijuana – which is also derived from cannabis plants – on account of its low tetrahydrocannabinol (THC) content.

In construction, hemp fibres can be used in fibreboard, insulation, and plaster.

However, a key use of the material involves structural insulated panels which are manufactured using a product known as hempcrete.

Hempcrete is a typically a mixture of hemp fibres, lime and water.

Structural panels which use this are typically manufactured by laying wooden frames flat and filling them with a hempcrete mixture.

An important advantage of hemp lies in the benefits of its use for the environment.

As mentioned in the previous article, these include the ability to store carbon, high insulating qualities, being a renewable resource and the ability of hemp plants to improve soil health and support biodiversity.

Other benefits include its performance in terms of fire resistance and acoustic insulation/soundproofing, its benefits for indoor air quality (by managing humidity and reducing mold growth) and the aesthetic and physical comfort effects which are associated with biophilic environments.

As also noted in the aforementioned article, however, several challenges have meant that hemp building uptake has thus far been limited.

These include issues with cost competitiveness, an absence of standards for hempcrete construction, a lack of scale in production and a lack of coordination across the hemp supply chain.

Whilst hemp can be used across various building types, Maskiell’s experience is focused around public sector buildings.

This is because her firm (which with a team of six is relatively small) serves only public sector clients or public institutions – a strategy which reflects its decision to focus entirely upon fostering social connection and enriching public life.

The firm was founded ten years ago. Of these, the last five years have been spent advocating for use of plant-based materials on public sector buildings.

(Powerhouse Place. Image via Public Realm Lab)

Successful and unsuccessful examples

In her presentation, Maskiell described several projects on which her firm has advocated for use of hemp.

The first was the three building Powerhouse Place complex located along the ‘Mighty Murray’ in Mildura in Victoria’s north-west.

Delivered for the Mildura Rural City Council, this is believed to be the first Australian public building on which hemp has been used.

The project – which involved the overall transformation of an industrial precinct into a place for people – was awarded the Victorian Architecture Medal by the Australian Institute of Architects in 2024.

It received positive coverage in media outlets such as the ABC and The Guardian.

In terms of hemp, a key selling point for the Council was that the design team was able to demonstrate how the product’s use aligned with Council’s environment and climate resilience policies.

Nevertheless, several challenges were encountered in getting hemp across the line.

These included:

• The three shortlisted contractors offering significant cost savings to the Council if hemp was eliminated from the design during the process of tendering for the building contract.
• Trades including renderers were not being familiar with hemp – something which was problematic as rendering is essential in order to ensure adequate waterproofing performance.
• Challenges in gaining the building approval. This included considerable political advocacy and design effort across several years along with a drawn-out process to prepare and finalise the necessary paperwork. With hempcrete being a new product, a performance solution was needed to demonstrate compliance with the National Construction Code. A second performance solution needed to be prepared after the first was rejected by the building surveyor.

Another success story has been the Meeniyan Community Hub which has been delivered for the South Gippsland Shire Council south-east of Melbourne.

Compared with Powerhouse Place, the process of getting hemp onto this project was much simpler as the design team was able to point to the Mildura project (including photos of the actual building under construction) along with the positive media attention which this was generating.

As with the Mildura complex, alignment with Council sustainability and environment policies was a key selling point.

On this project, a mix of prefabricated block and in-situ hemp construction was used. This was beneficial from a material handling viewpoint on a tightly constrained site.

In addition, a decision was made to leave the hemp exposed on the internal side.

This has been critical in terms of growing public awareness as the community is able to see the material and sense its biophilic qualities.

At Mildura’s Powerhouse, by contrast, the building was fully rendered. Visitors would not be aware that hemp was used without being told that this is the case.

Still, the project has not been without challenges.

Due to the fire resistance level which was required for this building, the design team opted for a product that was CodeMark certified.

(Administered by the Australian Building Codes Board, the CodeMark Certification scheme is a means by which new or innovative building products can demonstrate compliance with the National Construction Code for its intended uses via a nationally accepted process.)

Whilst this delivered an easier approval process, it necessitated the use of imported hemp. This was not ideal on account of both the environmental impact of transportation and lack of benefit for the local economy.

Over time, it is hoped that local hemp production will develop to the extent that locally grown products will be CodeMark certified.

However, the team has not always been successful in getting hemp across the line in procurement.

On a recent public project in Beechworth, Public Realm Lab proposed a prefabricated system using hemp but was unable to get sufficient documentation and warranties in place in order to gain local government sign off.

(Meeniyan Community Hub. Image: Public Realm Lab)

Going further

Whilst these were impressive, Public Realm Lab is seeking to drive further expansion in the use of hemp.

This includes:

• Going beyond new builds to incorporate hemp use in repair and adaptive reuse.
• Greater use of the material in social housing.
• Incorporation of hemp substitutes into other parts of the building (such as joinery) in addition to its use as a primary construction system.
• More in-depth life-cycle analysis about hemp impacts.

Speaking to the first point, Maskiell says that one project which Public Realm Lab has in the works involves the Rutherglen Hub precinct in Victoria’s north.

This project aims to transform an underperforming building by stripping the building back to its structural frame, retaining the concrete and steel and reconstructing a hemp building around that.

The project is fully documented but is yet to secure funding.

On the final point, The Public Realm is aiming to go into greater depth to demonstrate the environmental benefits of hemp through use of carbon accounting and demonstrating alignment with the achievement Green Star certification and Passivhaus.

Up until now, the firm was able to provide estimates about carbon reductions that were achieved through hemp usage. However, these have been relatively raw in nature.

(Hemp construction. Image: Anna Maskiell)

De-risking hemp

In order for hemp to gain mainstream traction, Maskiell says that action is needed to reduce the risk associated with use of the product.

This includes risks which associated with political factors (such as disassociation hemp from illicit drug use), procurement, approvals and post-construction care.

Recommended actions include:

• Ongoing work to demonstrate alignment with sustainability and economic development policies and triple-bottom-line benefits.
• Removing any perceived association of a link between the product and illicit drugs.
• Building head contractor and trade contractor knowledge and product familiarity – ideally though accreditation or formal training.
• Building a diverse and competitive market for hemp products.
• Ongoing work to develop a series of Australian standards for hempcrete construction (the industry is currently working with Standards Australia and other stakeholders on this).
• Product certification (i.e. CodeMark) along with necessary product information and documentation.
• A coordinated build-up of product systems with clear maintenance and warranty information. This includes ensuring that products are compatible with other materials such as sealants and even anti-graffiti coatings.
• Evidence of suitability of product systems for outside domestic construction.

Maskiell says that efforts in these areas will deliver substantial results.

She says that the opportunity is there as there is growing political alignment and increasing awareness about the benefits of hemp construction.

“If I had a magic wand, these are the things I would be working on,” she said.

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