Expert article
Modifier 17 April 2024
by Donal O'Herlihy, UIA Expert

Does circularity help to reduce carbon emissions?

Smoking chimney
Smoking chimney
This articles considers whether there is a link between circularity and carbon emissions. It also uses the RE/SOURCED project as an exemplar to show how adopting circularity can notably reduce the carbon impact for a renewable energy project of this kind.

Our previous article highlighted the challenges faced by RE/SOURCED when incorporating  circularity in the project design and delivery.  Its conclusion raised the question as to why you might bother to adopt circularity at all when implementing a renewable energy project. 

RE/SOURCED was not limited just to creating a DC Smart Grid - it also involved building refurbishment through converting parts of the main generation building into offices.  Building construction is a significant contributor to the worlds carbon emissions and materials footprints, accounting for about 40% of each. Most emissions associated with buildings result from their operations—primarily heating and cooling. But the embedded emissions (explained in depth below) in building materials used in construction still account for 28% of all construction-related emissions[1].

For RE/SOURCED, one of the key aims of the project was to apply circular economy principles when creating its renewable energy smart grid, energy generation and storage system. The project adopted circularity due to the waste and carbon emission benefits it would deliver.

So how might the project achieve these circular benefits?  And what “emissions added-value” might a circular project deliver?  Before considering these questions, we first look at defining what is circularity.

Let's look first at its predecessor, the linear economy.  The linear economy best describes industry and consumer driven economic activity and growth of the 19th, 20th centuries and early part of the 21st century.  It is sometimes termed the “take-make-waste” economy.  This description applies equally to foodstuffs as it does to manufacturing and construction.

Linear economy is framed within a product lifecycle that sees raw materials existing for conversion into products that are then used and discarded.  Historically, their disposal has been mostly to landfill or at sea, but it also includes incineration.

Circular economy is fundamentally different to the linear economy approach.  It seeks both to minimise the resources used in producing a product, to extend its lifetime through repair or replacement and to re-utilise as much of these original resources as possible when the product reaches its end of life. The “5 Rs” are often used to frame circular economy activity:

  • Refuse - do not accept the offer of a new item (e.g. a plastic bag when shopping)
  • Reuse - reuse the item for its original purpose (with minimal or no processing involved)
  • Refurbish - assess the functionality of the product and renew or repair parts that have failed
  • Remanufacture - return a used product to at least its original performance with a warranty that is equivalent to or better than that of the newly manufactured product.
  • Recycle - is a process, where used and discarded materials (waste) are transformed into new products.  Recycling is suboptimal as the new products tend to be of lower value than the original (for example using a dismantled aeroplane fuselage as a raw material for bicycle frames).

The Ellen McArthur Foundation defines circular economy as a system where materials never become waste and nature is regenerated. In a circular economy, products and materials are kept in circulation through processes like maintenance, reuse, refurbishment, remanufacture, recycling, and composting. The circular economy tackles climate change and other global challenges, like biodiversity loss, waste, and pollution, by decoupling economic activity from the consumption of finite resources. The linear economy tended to treat resources as infinite (up to the point that they disappeared) and land as worthless until it was put to productive use.

These principles underpin the EU’s Waste Framework Directive. The Directive is a central thrust of its circular strategies and lays down basic waste management principles. It requires that waste be managed:

  • without endangering human health and harming the environment
  • without risk to water, air, soil, plants or animals
  • without causing a nuisance through noise or odours and
  • without adversely affecting the countryside or places of special interest.

It also has associated targets for 2025 - namely the preparation for re-use and the recycling of municipal waste shall be increased to a minimum of 55 %, 60% and 65% by weight by 2025, 2030 and 2035 respectively.

Circularity has both a direct and an indirect effect on carbon emissions.  Directly, and especially where food waste is concerned, landfill sites produce significant quantities of methane gas as the waste breaks down.  Methane is a particularly aggressive greenhouse gas that attacks the earth’s ozone layer and notably contributes to raising global atmospheric temperatures. Separately, landfill sites can contaminate water courses for local communities.  RE/SOURCED is not aiming to reduce methane emissions directly - however, by refurbishing a large part of the original building structure, it has limited the amount of construction waste, and the waste associated with large batteries containing lithium and chromium, going to landfill.

In addition, the benefit of RE/SOURCED is the amount of “embedded carbon” it is retaining.  But what is embedded carbon?

Embedded (Embodied) Carbon & Operational Carbon

Embedded (embodied) carbon in a product or structure is the amount of carbon required for its production or creation. For a building, this would be the carbon contained within all of the materials used to construct the building’s fabric and that associated with the fit-out components the building contains (e.g. electrical, heating and ventilation systems).

When creating a new building, architects and designers often must decide whether it should be a new build or a renovation of an existing facility. This decision has a significant impact on both embedded carbon and operational carbon.

Operational carbon for a building is the amount of carbon emitted through the operation of the facility (after it is built). It also includes the carbon required for maintenance, upgrades, and component replacement during the building’s life.

The whole life carbon is the combination of embedded carbon and operational carbon.

If the municipality had demolished the Transfo building, cleared the site and then constructed a new facility, there would have been effectively four groups of carbon emissions:

  • Embedded carbon contained in the materials that comprised the demolished Transfo building
  • Carbon associated with the demolition process and transportation of waste to landfill
  • Embedded Carbon within the new building’s materials and components
  • Operational Carbon from the new building’s operation.

As the municipality renovated the Transfo building, its embedded carbon is effectively “saved” and they have avoided the additional carbon loss that would have been emitted through a new build. For simplicity, carbon emissions associated with the demolition process are assumed to be similar to those of the renovation and upgrade process while the Operational Carbon levels of the renovated building are assumed to be similar to a new build as the renovation was conducted to modern building standards. Thus, by renovating an existing building:

  • There are substantial savings to carbon emissions
  • There is a substantial reduction in the amount of waste going to landfill
  • The ‘re-use’ of the asset is maximised.

This shows the positive link between circularity and reducing carbon emissions.

While RE/SOURCED has delivered significant construction-related benefits as cited above, the project is delivering further value through its circular Smart Grid.

We covered the circularity benefits and challenges in a separate article (here).  The goals of RE/SOURCED included a number of “re-use cases” (not recycle), notably for the supporting structure for the most significant solar PV installation and Battery Storage.  These have delivered additional benefits for the environment.

Circularity can help to substantially reduce carbon emissions. 

RE/SOURCED shows that circularity can be applied effectively to a (renewable) energy infrastructure project and that doing so delivers the dual benefit of waste reduction and carbon savings.  Circularity is therefore a critical element for the EU’s climate mitigation activities.

The adoption of circular principles is best done at the design stage so that waste can be “designed out”.  The goal is to keep materials from being discarded through maintaining their reuse in applications that reflect, as closely as possible, those of their originally designed purpose.

Adopting circularity need not lead to inferior outcomes in terms of performance and can help organisations to significantly reduce their carbon emissions.