Embodied carbon in construction accounts for 14% of national emissions and could increase without action, threatening climate targets. MARION JAMMET, Head of Policy and Advocacy, IGBC, details building elements responsible for most embodied carbon and how the issue might be tackled under new regulatory policies.

In Ireland, embodied carbon in construction and the built environment accounts for 14% of national emissions. Without targeted actions, these emissions – associated with the production of building materials and the construction and renovation of buildings and infrastructure – could increase significantly in the next decade, jeopardising our climate targets. Addressing embodied carbon is often perceived as complex, but with new policies set to regulate these emissions, there are simple actions that can be taken to reduce them.

In Ireland, embodied carbon in construction and the built environment accounts for 14% of national emissions. Without targeted actions, these emissions – associated with the production of building materials and the construction and renovation of buildings and infrastructure – could increase significantly in the next decade, jeopardising our climate targets. Addressing embodied carbon is often perceived as complex, but with new policies set to regulate these emissions, there are simple actions that can be taken to reduce them.

Identifying carbon hotspots in buildings and infrastructure

As part of the Indicate project, the IGBC and SEAI are working on a national methodology for calculating the life cycle GWP of buildings. This will be released by Q3 2025.

The early results of Indicate have allowed the IGBC to identify common carbon ‘hotspots’ in buildings. Not surprisingly, these correlate with heavier building elements and those that need to be replaced more during the building’s lifetime – structural frames and substructures, facades up to completion, and energy systems over the lifetime of the building¹.

These findings should encourage all designers to prioritise the reuse of existing structures, where possible, and to focus on reducing the embodied carbon of these elements when building new. If using concrete, for example, designers should require optimised strength and quantity with maximum cement replacement. Minimising the volume of concrete required and the cement therein should have the greatest impact on the embodied carbon of a new building. Published Environmental Product Declarations (EPDs) give the most accurate information; they show that bio-based materials generally have lower embodied carbon than alternatives such as steel and concrete, and they are lighter, which may allow for smaller substructures. By requiring EPDs for these high-mass elements, more of the building’s embodied carbon can be measured accurately.

Planning for lower embodied-carbon homes

Simple actions in the design and planning phase can also help to reduce embodied carbon emissions. Last year, the IGBC and University College Dublin, with support from Construct Innovate, developed ‘Viable Homes: Guidelines for planners on the design and building of low carbon, low rise, medium density housing in Ireland’. This guidance shows that significant carbon savings can be achieved by rethinking the use of carbon-intensive construction materials in our dwellings and by adopting planning approaches that minimise car parking, new roads, and new infrastructure.

Initial findings show that greenfield housing developments outside towns and cities can contribute up to 30% more embodied carbon per home than equivalent infill developments that use existing infrastructure.

Viable Homes recommends prioritising housing development on empty or underutilised lands in existing urban centres and building connected neighbourhoods with minimised car parking. This can also help to address transport emissions by reducing car dependency. Viable Homes also highlights that connected dwellings such as terraced houses offer a significant carbon reduction. A side gable wall, which is typically found in semi-detached houses, generates approximately four to five times more embodied carbon per square metre than a party wall between dwellings on a terrace.

IGBC Going further

The IGBC has developed new on-demand courses on Whole Life Carbon Emissions and Circularity. These are available on the IGBC website. During World Green Building Week (09 to 15 September), the Circularity in The Built Environment 101 course will be FREE for all. Use the discount code WGBW24 at https://learn.igbc.ie/

Further information on these tools and research findings can be found at www.igbc.ie

1 Based on 20 assessments carried out independently by BDP, Cluid Housing, ECR, Grangegorman Development Agency, Helena McElmeel Architects, Henry J Lyons, MMC, Meehan Green, MMP, PM Group, Scott Tallon Walkers, Wain Morehead Architects and Walls, but crucially, all using the same draft national methodology to measure the global warming potential of buildings across their life-cycle, developed by the IGBC in partnership with SEAI.