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Oct 11, 2023

Embodied carbon in building services: It’s complicated

Embodied carbon in the built environment is getting plenty of attention, particularly big ticket materials such as concrete, steel and aluminium. But buildings contain other elements too. Building

Embodied carbon in the built environment is getting plenty of attention, particularly big ticket materials such as concrete, steel and aluminium. But buildings contain other elements too.

Building services – which include heating, ventilation and cooling and refrigeration, fire safety, lifts, escalators, and lighting – is one of these elements. Collectively, these services represent up to 15 per cent of upfront carbon in commercial buildings, and around 30 per cent of the whole-of-life embodied carbon. Unlike structural elements, building services are periodically replaced during the life of a building, costing more carbon.

So, it’s an issue we need to tackle. But talk to the stakeholders in this space, and you will hear a common refrain: it’s complicated.

For a start, building services are not a single material. An HVAC system can contain thousands of parts. And the supply chains for these parts are complex – often many layers deep and highly dynamic, depending on availability and price.

This makes measuring embodied carbon difficult. A typical environmental product declaration (EPD) lasts five years, while the embodied carbon of a product may change from month to month.

Manufacturers are understandably reluctant to invest in developing EPDs if they are not accurate, and they are concerned that if we use EPDs to drive customers’ decisions to purchase one brand over another, we won’t actually get the right result. There are also concerns over the cost of creating the EPD, given the complexity of the supply chain and the range of data needed.

On top of this, building services impact both embodied and operational emissions. If we are going to procure for the best environmental outcomes, both these things must be considered. What is the benefit of purchasing a low-embodied carbon (EC) package unit if it has poor energy efficiency? Or purchasing low-EC ductwork if it lasts only half as long as metal ductwork? Similarly, Passive House buildings – great for reducing operational emissions and improving occupant health – may lose out if embodied carbon is the sole focus.

And stakeholders in the building services space note that there is still a lot of work to be done to reduce operational emissions. If we are going to allocate our finite resources, this is where we will get best bang for our buck. Work is required not just on energy efficiency, but also on refrigerant management and maintenance. The first two are under way, but the last needs attention.

There are also questions of accounting, particularly when it comes to refrigerant. A unique aspect of HVAC&R equipment is that refrigerants are counted in the embodied carbon totals for products, based on the assumption that some of it will leak during the life of the building. The Air-Conditioning and Refrigeration Equipment Manufacturers Association of Australia (AREMA) suggests this should be accounted for in the operational emissions of the building. Another worthwhile suggestion is that better maintenance of building services could earn points in ratings systems, because it prolongs the life of equipment, and therefore reduces operational embodied carbon.

So yes, it is complicated.

But despite all this, the need for action remains. The industry cannot sit idle on embodied carbon.

One suggestion is to start with industry averages developed in collaboration with manufacturers. For example, an EPD for chillers of a certain capacity. This would at least allow the industry to take embodied carbon into account in the design stage. Again, it’s a complex equation, not just a matter of material or unit substitution. Buildings are systems. We need to think about other strategies, such as passive heating and cooling.

Although EPDs are difficult to develop and still uncommon in the building services space, a methodology called TM65 has been developed to provide a better picture. This is incorporated into Green Star’s Responsible Products and Upfront Carbon frameworks and offers a way forward. There is, however, more work to do here, particularly around leak rates for refrigerants, which have a major impact on the overall calculations.

Of course, EPDs are still available for companies that want to differentiate their products – and perhaps for those who are prepared to really commit to low-EC manufacturing. This feeds into the bigger question about how we produce and consume building services.

And even if we can’t accurately measure CO2e in a printed circuit board (PCB) or screw, that shouldn’t paralyse us. Modern slavery regulations have shown us that supply chains may be complicated, but they are not unfathomable. We may be able to use a similar roadmap for embodied carbon.

The first step is to do a ‘hotspot analysis’ identifying top elements of a given product, and gain a better understanding of where those materials come from. Companies already engage in this type of work in other areas of the built environment, and there are several other sustainability certifications that could be leveraged for building services to navigate their supply chain. For example, in air-conditioning systems steel, copper, aluminium and plastic are the four main components. A manufacturer could look to procure from companies that have certifications such as ASI-certified aluminium, Responsible Steel or SSA-certified steel, or The Copper Mark.

Just as head contractors are sending a demand signal to the market for low-EC buildings, it is in the power of manufacturers to start asking their suppliers for low-EC parts. In fact, one of the most useful conversations right now – particularly in the building services space – would be between those head contractors and the manufacturers, so that they can understand each other’s objectives and challenges better.

The demand is there. Organisations such as Atelier Ten are already setting embodied carbon targets for building services. Manufacturers that recognise this opportunity and invest early in developing low-emissions technologies are sure to be well positioned in the economy of the future.

It’s also worth remembering that the building services sector has showed an incredible ability to adapt over the years. Refrigerant transition, for example, from CFCs, to HCFCs, HFCs and now to other low-GWP alternatives. Improvements in energy efficiency too – Daikin has improved the average energy efficiency of its products by 60 per cent over the past 25 years.

The time is now for embodied carbon. Yes, it’s complicated, but it’s also important and it’s achievable.

This article is part of a series of articles from MECLA on how it is helping to reduce embodied carbon in the built environment, published with the financial assistance of MECLA and WWF.

Alexi Barnstone is a Project Officer for Climate-KIC and part of the MECLA secretariat. More by Alexi Barnstone, MECLA

Mark Vender is the advocacy and policy manager at AIRAH More by Mark Vender, AIRAH