Caroline Noller on the case for a NABERS-style embodied carbon scheme
Willow Aliento | 6 March 2018
Addressing energy use in the built environment is just one aspect of the carbon reduction challenge, according to The Footprint Company chief executive Dr Caroline Noller. Addressing the embodied carbon in building materials is also vital.
Dr Noller told The Fifth Estate international data showed that more than 50 per cent of global carbon emissions ended up in a building or infrastructure material of some kind.
To grab this bull by the horns, equipping designers with the knowledge to make good carbon decisions is key.
“Design decisions including materials selection can change the footprint of the building,” Noller says.
This is where her idea of a NABERS-style rating scheme for embodied carbon in buildings could create real traction.
Her company has already developed a similar system based on the extensive footprint analyses that it has carried out on building materials, building systems and building operation.
Noller says embodied carbon “bands” are presented to clients, who can then make a decision about which band they want their building to achieve. The goal is to achieve a band that is better practice than business as usual.
Each band sets a cap on total embodied carbon emissions in the building.
The chosen band then allows designers to innovate in their decision-making and come up with a pathway that will achieve the specified embodied carbon figure.
So if a designer chooses the high-carbon vitrified tiles for bathrooms, that choice might be balanced with low-carbon Hebel block walls, she explains.
It is a simple calculation that allows the footprint to be calculated in a “design-driven way”.
“This then opens it up for all kinds of different materials.”
As well as a NABERS-style scheme for embodied carbon, Noller says a white certificate scheme similar to the NSW Energy Savings Scheme would incentivise the idea for asset developers and owners.
A white certificate scheme that delivered a tradeable certificate with a financial value when embodied carbon ratings are improved would reduce the capital cost of making the low-carbon choice.
“An owner needs to have a business proposition [such as the carbon certificate],” Noller says.
This would also eventually drive us towards building better, and reduce carbon footprints – “all the directions we need to go in.”
It also helps get owners and developers to prefer lower-carbon materials, as it would become a clear case of “we don’t have a [carbon] budget for dirty materials anymore”.
The approach would reward designers that make better decisions and set trends towards low-carbon materiality, as well as the owners that get onboard.
“The advantage of embodied over operating carbon abatement is that it is certain and immediate and does not rely on human behaviour over many years.”
How does a designer get the right information?
One of the challenges for designers is getting accurate information on the carbon footprint of materials and then comparing the possible choices within the whole building design context.
Noller gives the example of aluminium and steel. Aluminium as a virgin material has three times the embodied energy of steel on a kilo for kilo basis. But when aluminium is recycled, its carbon footprint is much smaller than steel.
At the same time, aluminium is one-third the weight of steel – so in terms of lineal dimensions, even virgin aluminium is even with steel in the carbon footprint stakes.
Noller says it is “critical to understand” that the design choices are not just about carbon neutral products.
Carbon neutrality is not just a factor of what a product is made from and how, it can also take in aspects such as offsets for the cradle-to-gate product emissions.
The key thing designers and specifiers need to look for in the first place is an environmental product declaration, she says.
They are not all created equal, however. They include EPDs generated by certification schemes such as Good Environmental Choice Australia, Global Green Tag and the Australasian EPDs, as well as international schemes such as Blue Angel.
A useful EPD will show impacts from cradle to gate or cradle to grave in terms of carbon emissions.
A lifecycle analysis – which may or may not be part of an EPD – will also show carbon as one of the product’s impact categories.
A good quality EPD will also be transparent.
“An EPD is a key place people should start to look for the calorie content of their material,” Noller says.
One of the issues with some EPDs is the way the information is presented. Noller says the preparer of an EPD has to nominate the functional unit that is being assessed.
This does not always result in useful data from a design point of view. Noller gives the example of a plumbing pipe manufacturer with EPDs that give carbon impacts in terms of kilograms of product – but what a designer needs to know is how much 900mm pipe is that exactly?
Steel also often gives its footprint in terms of CO2 per kilogram.
“But what is one kilogram of steel in terms of building outcome?”
Her company recently launched a digital database and calculation tool, the Green Book, which translates EPD and other information into data that correlates to actual design.
For example, a user can be looking to decide between steel and aluminium products for ceiling framing. The user can input the grid drawing information and then produce a calculation of the carbon footprint for each material.
“That’s the missing piece for designers to make decisions,” Noller says.
“Most of the carbon in a building is in early decisions. That’s the important thing we need to address.”
Noller says it is “important we have an interest in low carbon and carbon neutral buildings”.
That also means looking at aspects such as churn.
While at architect might specify materials that will last for 100 years, the average lifetime for a fitout is around 10 years and for a building 25 years, Noller says.
One solution is to encourage design that is appropriate for adaptive re-use or recycling at end-of-life.
Another approach is to accept the fact that “churn happens” and recognise that there is a place for “cheap, nasty, disposable” materials.
“I think there’s a real place for that”.
For example, the trend is for retail centre amenities to use vitrified ceramic tiles. Noller questions this, as it is rare for those facilities to have a lifetime longer than 10 years or so.
This type of tile has ten times the footprint in terms of embodied carbon of a choice such as epoxy over concrete, vinyl or polished concrete.
Hospitals have been choosing the lower-carbon and cheaper option for years, Noller says, recognising that materials such as vinyl are easy to clean and replaceable when wear and tear makes it necessary.
Yet another is to design in a way that considers fashion and aims to achieve the type of outcome that is both designed for 150 years and will achieve that classic building status found more frequently in places like Europe.
The proposed scheme for rating buildings on their carbon is a key part of giving any approach real momentum.
“Carbon life cycle assessment methods and inventories have improved vastly in the last decade and sufficient data and LCA expertise exists which now makes a scheme accessible and plausible.
“One simply needs to consider the regulatory requirement for materials LCA in The Netherlands and France to understand that such a scheme has a clear basis for deployment.”