Rammed earth

Execs: Low embodied vitality, excessive thermal mass, fireplace resistant and, normally, recyclable
Cons: Requires specialised contractors, offers restricted insulation, is labour intensive to recycle and will be costlier than different supplies

Rammed earth partitions are constructed by ramming a mix of gravel, sand, silt and a small quantity of clay into place between flat panels referred to as formwork.

Trendy rammed earth is usually stabilised utilizing a small quantity of cement (sometimes 5–10 per cent) to extend its power and sturdiness.

‘Rammed earth typically has low embodied vitality and low environmental influence, however this relies on cement content material and the supply of the supplies. Supplies which might be quarried and transported lengthy distances to the development web site can have greater embodied vitality and influence,’ says Nick Walters, mission designer at Altereco Design.

‘Just like concrete, rammed earth will be damaged down and reused in new mixes. This includes fairly a little bit of effort to interrupt the wall down and crush the fabric into smaller, extra constant particles so as to be reused.’

Rammed earth offers wonderful thermal mass (it’s capable of take in and retailer a considerable amount of warmth after which slowly launch it over time) however restricted insulation (which, typically talking, acts as a defend in opposition to the entry and lack of warmth).

Skilled specialised contractors are important when constructing a house in rammed earth, making it much less accessible than another supplies.

Hempcrete

Execs: Carbon sequestering, recyclable, excessive thermal mass, bushfire resistant and doesn’t requiring portray
Cons: Labour intensive to supply, at present few Australian suppliers and will be costlier than different supplies

Hempcrete is a composite materials product of hemp, sand, and a hydraulic binder that provides an identical textural look to rammed earth or mudbrick.

Nick from Altereco Design says hempcrete is a ‘carbon-sequestering constructing materials from the expansion of hemp to the carbonation of lime within the partitions for the lifetime of the constructing… It reduces additional vitality consumption resulting from its wonderful insulation and hermetic qualities.’

‘Hempcrete may assist regulate indoor temperatures by absorbing extra warmth through the day and releasing it at night time when the temperature drops,’ says Natalie Lanksch, inside designer at Altereco Design.

As well as, hempcrete is a recyclable materials that may be simply damaged down for use in a brand new combine. It’s additionally bushfire resistant (as much as BAL40), and vapour permeable (serving to to manage humidity.)

As a result of labour required (and to a lesser diploma, a scarcity of hempcrete producers in Australia), this materials will be extra expensive than different supplies.

‘Whenever you examine the general price of a accomplished hempcrete wall (with render to either side), the price is often barely greater than a typical light-weight timber framed wall with insulation, vapour membrane, and plasterboard,’ says Nick.

James Goodlet, director of Altereco Design, provides, ‘Industrial hemp is lastly being grown in Australia and now there are processing services coming… This improves the acquisition price and upfront carbon depth.’

James says, ‘We now have just a few tasks which have used hempcrete as a main materials for exterior partitions… They only really feel superb, plus you realize that the house goes to supply a steady and comfy local weather 12 months spherical.’

Timber

Execs: Pure insulator, low embodied vitality when produced ethically, renewable, carbon sequestering and recyclable when untreated
Cons: Low thermal mass, topic to shortages and will be costlier than different supplies

There are tons of of timber varieties, all of that are naturally renewable.

That being stated, there are a number of components to contemplate when utilizing timber in building. What makes this materials ‘sustainable’ relies on the way it’s harvested and transported.

‘Timber choice is kind of sophisticated,’ says James Goodlet, director of Altereco Design. ‘This a part of the trade is fraught with greenwashing. Other than demanding appropriate chain of custody certification [how the Forest Stewardship Council (FSC) verifies that forest-based materials are credibly used along the product’s path from the forest to becoming finished goods] be supplied, deciding on a timber species that’s match for objective is paramount.’

Breathe often makes use of timber of their tasks for structural and beauty functions.  ‘Timber is a pure insulator which might scale back vitality wants when utilized in frames, home windows, doorways, and flooring,’ says Bettina Robinson, director of interiors at Breathe.

‘Timber can sometimes be sourced domestically, is light-weight, and makes use of comparatively little vitality to transform the uncooked materials to a constructing product, compared to different structural supplies equivalent to metal and concrete.’

She provides, ‘We set up all recycled floorboards with nails, not glue, to allow them to be recycled once more on the finish of the constructing’s life.’

Considerably, timber is likely one of the few renewable supplies that contributes to the discount of carbon emissions. ‘Carbon from the ambiance is taken and saved inside timber throughout progress and makes up 40-50 per cent of its gross weight,’ says Bettina.

The cons of timber embody that it’s topic to shortages, presents low thermal mass, and it’s a flamable materials. ‘[Yet], timber is sluggish and predictable in the best way that it burns, which supplies it pure fireplace efficiency capabilities,’ says Bettina.

James says provides of timber have stabilised and prices have decreased this 12 months following big shortages and worth rises in Australia in 2021.

Clay brick

Execs: Excessive thermal mass, sturdy, fireplace resistant and accessible
Cons: Vitality and resource-intensive to fabricate and a comparatively poor insulator

Conventional clay bricks are a sturdy and low-maintenance building materials. They’re excessive in thermal mass, possess good compressive power, and have weather-resistant, fire-resistant, and acoustic insulation properties.

For the most effective sustainable outcomes, Breathe prioritises the specification of bricks within the following order: locally-sourced recycled bricks, adopted by Australian-made carbon impartial bricks, then Australian-made bricks.

‘Kiln firing sometimes requires excessive pure gasoline consumption and so is excessive in embodied vitality,’ explains Bettina Robinson from Breathe.

‘Carbon impartial bricks utilise biomass gasoline (sometimes sawdust) in kiln firing as a alternative to the burning of pure gasoline. These bricks are nonetheless comprised of virgin materials, so the usage of locally-sourced recycled brick is all the time most well-liked.’

Bettina provides the sturdiness and lifespan of brickwork ought to be weighed in opposition to their embodied vitality. ‘The place brickwork can serve a number of functions and scale back the necessity for extra construction or cladding layers, we determine it as an acceptable materials alternative.’

Mudbrick

Execs: Very low embodied vitality, pure materials that may be produced onsite or sourced, comparatively cheap, recyclable and fireplace resistant
Cons: Poor insulator (it’s usually crucial so as to add insulation to mudbrick properties to realize Nationwide Building Code compliance throughout most of Australia)

Mudbrick is likely one of the oldest constructing supplies on this planet. This materials solely requires earth and the vitality of the solar to supply, and subsequently has very low embodied vitality and environmental influence.

Mudbricks are made by mixing earth with water and fillers equivalent to straw, inserting it in a mould, and ready for it to dry.

Regardless of all the fabric’s professionals, mudbricks are not often utilized in trendy Australian properties. ‘It’s estimated that 30 per cent of the world’s buildings are product of mud, [but] it’s neglected within the west. It’s a low cost, sustainable, native and completely versatile constructing materials,’ says panorama designer Sam Cox of Sam Cox Panorama.

‘[Using] human vitality or labour, moderately than industrial manufacturing, is essential to their low embodied vitality and price. At an approximate price of $100 a sq. metre — and eradicating the requirement of inside wall linings — it’s price efficient.’

Sam used mudbrick to assemble his own residence in Wattle Glen, Victoria constructed within the 12 months 2000. ‘We chosen this materials for a number of causes together with finances restrictions, native availability, aesthetic attraction and it additionally adheres to the custom of mudbrick constructing within the Eltham space wherein we stay,’ he says.

‘I used to be the owner-builder, however as I used to be working full time, I might solely work on it after hours and on weekends with the assistance of native trades and mates. ‘To hurry issues alongside I purchased the mudbricks. They have been made only some kilometres away from domestically sourced clay and delivered to the positioning.

‘I laid the bricks myself, rendered them with the standard recipe of cow dung and native river silt, and painted with a mudbrick color coat — a product developed by Grimes & Sons in Eltham.

‘It’s a materials that’s straightforward to construct with for an on a regular basis one that is taking over an proprietor construct.’

Sam attributes the declining reputation of mudbrick to trendy constructing requirements. ‘Sadly, mudbricks haven’t fared nicely resulting from not becoming the evaluation course of for present vitality ranking requirements for brand new buildings. The mudbrick trade has since stalled when it comes to new builds,’ Sam says.

To realize the degrees of insulation wanted for sustainable home building and to realize Nationwide Building Code compliance throughout most of Australia, it’s usually crucial so as to add insulation to mudbrick properties.

‘We’re very glad to be dwelling in a mudbrick home. It’s a dwelling that’s solely of place and embedded within the panorama… the partitions have actually come out of the bottom,’ Sam says.

‘I feel people who find themselves interested in this model of dwelling perceive it as a lifestyle, and usually are not inclined to the overly snug, climate-controlled surroundings of standard properties. Our mudbrick dwelling features nicely sufficient for us in winter with a single wooden heater and no air conditioner is required in summer season.’

Concrete

Execs: Excessive thermal mass, accessible, normally recyclable and sturdy
Cons: Excessive embodied vitality, poor insulator and labour intensive to recycle

Concrete is essentially the most broadly used building materials on this planet. Its sustainable properties are advanced, because it’s a cloth that gives nice thermal mass, however is excessive in embodied vitality.

The chemical and thermal combustion processes concerned within the manufacturing of cement are a big supply of carbon dioxide (CO2) emissions. Annually, greater than 4 billion tonnes of cement are produced, accounting for round 8 per cent of worldwide CO2 emissions.

‘It has excessive ranges of embodied vitality as a result of mining and processing of pure assets to manufacturing, transport and product supply,’ says Nick Walters of Altereco Design.

‘That is nonetheless low in comparison with MDF or glass, and really low in comparison with plastics, rubber, aluminium, metal and copper.

‘Concrete corporations are additionally providing lower-carbon depth cement mixes, which positively make the fabric much less carbon intensive — however nonetheless removed from eradicating its depth.’

Whereas concrete is technically recyclable, it may be troublesome to course of, and at present accounts for an enormous portion of building waste.