Carbon Accounting in Irish Construction

Industrialising construction to deliver

The widespread adoption of MMC, which encompasses offsite manufacturing and improved onsite techniques, is seen as a critical element in accelerating delivery and enhancing sustainability, productivity and quality across the built environment.

MMC, often facilitated by design for manufacture and assembly processes, allows for significant advantages, including reduced construction time and long term cost savings. Industry sentiment, particularly among established players, suggests that client demand is increasingly shifting towards modular and volumetric solutions.

Ireland already hosts a dynamic MMC ecosystem, with over 100 offsite manufacturing companies operating in the country, 27 of which provide complete MMC housing solutions. Experts believe the sector has the capacity to rapidly scale up annual housing output by 25,000 dwelling units if it is supported correctly.

Key actions to underpin this shift are actively progressing, including the Royal Institute of the Architects of Ireland developing a design for manufacture and assembly overlay to its Plan of Work, aimed at increasing understanding and implementation among design teams.

The public sector is also expected to lead this change through exemplar projects, standardised design, and procuring construction services that facilitate MMC at scale, as detailed in the Housing for All strategy.

Decarbonising concrete

While MMC addresses efficiency, regulatory shifts are forcing the industry to confront the embodied carbon of its materials. Concrete, an essential material, poses a specific challenge: the Irish cement sector was responsible for nearly 5%, or 4.8%, of Ireland's total national emissions in 2022, equating to 2.88 million tonnes of CO₂ equivalent.

To address this, the Government of Ireland issued a mandate for all state funded construction projects, including roads, schools and hospitals, from 1 September 2024. These rules legally prohibit the use of CEM I, the cement type associated with the highest emissions, in state agency funded projects.

The mandate aims to compel the use of low carbon cement. The Irish Concrete Federation has already launched representative ready mix environmental product declarations to aid transparency in material choices.

Irish research is also paving the way for material innovation:

• Engineers at Trinity College Dublin School of Engineering have pioneered a way to transform industrial biomass ash, a common byproduct, into high quality, low carbon concrete.
• The method has been proven to achieve a 51% reduction in carbon emissions without compromising the concrete's performance. This Enterprise Ireland funded initiative is actively seeking to broaden its adoption across the country.

How whole life carbon is measured

The calculation and reporting of whole life carbon emissions, specifically the global warming potential of buildings, is becoming a mandatory requirement under EU legislation, specifically the recast Energy Performance of Buildings Directive, EU/2024/1275.

The Sustainable Energy Authority of Ireland is responsible for developing the national methodology for assessing it for new buildings. The assessment covers all stages of a building's life cycle, A to D, including the production of materials, transport, construction, operational energy use, maintenance and end of life disposal, and it must comply with the I.S. EN 15978:2011 standard.

Key implementation dates and requirements include:

• Mandatory reporting rollout: from 1 January 2028, all new buildings larger than 1,000 m² must report their global warming potential, expanding to all new buildings by 2030.
• Public sector requirement: exchequer funded projects over a certain threshold must produce a whole life carbon assessment from 1 June 2026.
• Reporting metrics: the final indicator must be expressed in kgCO₂eq and reported on the Building Energy Rating certificate, showing the total impact per square metre of useful floor area.
• Data standardisation: to support accurate calculations at the early design phase, the SEAI is developing Ireland's National Embodied Carbon Database of Building Materials. It will provide generic data for materials consumed in Ireland, ensuring geographical representativeness. As projects mature, specific environmental product declarations should be used instead.

What is still missing

While the policy groundwork is laid, the industry stakeholders interviewed as part of the ongoing MMC research identify several gaps that have to be addressed before these approaches can scale.

Testing and certification

A persistent complaint across the sector is the lack of dedicated, domestic testing facilities. The industry urgently requires a national infrastructure of testing facilities for critical elements like fire safety, acoustic performance, thermal efficiency and the structural integrity of MMC and modular assemblies and their prototypes. Manufacturers currently rely on facilities in Belfast or the UK, which often forces them to repeat expensive testing for Agrément certification.

The National Standards Authority of Ireland Agrément certification process is crucial for new building materials and products for which national standards do not yet exist, especially for offsite and modular systems.

The circular economy lag

Despite the focus on sustainability and waste minimisation, design for reuse and design for deconstruction remain largely neglected in current Irish policy and practice compared to the overwhelming focus on MMC and design for manufacture and assembly for upfront productivity.

Documents like the Housing for All roadmap and other key publications mention reuse principles only sparingly, and usually in the context of repurposing existing buildings rather than designing new ones for future reuse. Research suggests that successful design for reuse requires standard connections designed specifically for disassembly, screw fixed rather than welded or adhered. Overcoming negative public perception of reused materials is also a necessary task for knowledge transfer initiatives.

Skills, digitalisation and standardisation

Stakeholders consistently emphasise the need for dedicated education, training and continuing professional development programmes covering MMC, design for manufacture and assembly, and digital tools like BIM, noting a lack of modular training in traditional university and college curricula.

To achieve the scalability MMC requires, there is strong industry demand for certified universal housing systems employing standardised typologies that allow for cost efficient production and repetition, while still permitting reasonable design variation. This approach would simplify procurement, mitigate risk and provide the volumetric pipelines needed for manufacturers to make the shift commercially viable.