D/RES landmark project

This landmark project is setting a powerful blueprint for decarbonising the built environment, demonstrating the achievability of whole-life carbon accountability for the Irish construction sector.

At the Altidore Gardens development in Newtownmountkennedy, property developer D/RES is not just building a creche and a community centre; it is erecting Ireland’s first privately-developed public buildings constructed to a Net-Zero Carbon standard and primarily from Mass Engineered Timber (MET). This landmark €3.2m project is a powerful, tangible statement on the future of sustainable construction in Ireland, moving the needle beyond operational efficiency to embrace whole-life carbon accountability. The project aims to address Ireland’s pressing need to decarbonise its built environment, a sector responsible for 37% of global carbon emissions in 2022, with 23% attributed to operational energy and 14% to the embodied carbon in material production and construction processes.

The significance of the project is evident when considering the list of key stakeholders who are invested in or engaged in its delivery. These include Construct Innovate, the University of Galway, the Irish Green Building Council and several government departments and steering groups. By setting a national benchmark for lowcarbon, high-performance construction, D/RES, in partnership with academia and industry bodies, is demonstrating that net-zero carbon principles are not just aspirational but eminently achievable.

The mass engineered timber mandate: a ‘timber first’ philosophy

D/RES’s journey to Net Zero carbon stems from a “timber first” policy, which already employs 95% timber frame construction in its houses, utilising PEFC-certified renewable timber sources. This commitment is further defined by adopting the RIAI 2030 Climate Challenge target of 450kgCO2e/m2 for residential embodied carbon as a baseline.

Its Tinakilly Park development in Co Wicklow, for example, achieved a score of just 270kgCO2e/m2 – significantly under the target – as well as being awarded the Climate Action and Sustainability Award at the 2022 Property Industry Excellence Awards, demonstrating D/RES’s commitment to creating sustainable homes for its customers.

The Altidore Gardens public buildings—a 600-sq-m creche and 400-sq-m community centre—represent the next logical step: Utilising MET to push the boundaries of embodied carbon reduction in public building typologies.

The choice of MET, which includes Cross-Laminated Timber (CLT) floor and wall panels supported by Glulam (Glued Laminated Timber) columns and beams, offers structural and environmental advantages, including the CO2 sequestration inherent in timber. It also leverages the efficiencies of off-site Design for Manufacturing and Assembly (DfMA) methodology, allowing for a swift, just-intime construction process.

Project procurement

The procurement for the project was completed in a mere seven weeks, with an erection time of eight weeks for both buildings, using only four erection staff and a crane operator.

Beyond the structural timber, the project meticulously incorporates other low- embodied carbon materials:

– Naturheld wood fibre insulation

– Green Coat roof sheeting (SSAB Net Zero certified)

– Bauder Sedum Green Roofing

– Ecocem Ground Granulated Blastfurnace Slag (GGBS) content in all in-situ concrete for the substructure

This comprehensive material selection is central to the project’s ambitious target: A reduction in carbon emissions, aiming for less than 10 kg CO2e/m2/year for both operational and embodied carbon.

Achieving net-zero: a whole life cycle approach

In the absence of a definitive Irish Net Zero Carbon certification, D/RES embraced a robust methodology, drawing on the Irish Green Building Council (IGBC) Net Zero Carbon Definitions and the UK Net Zero Carbon Building Standard.

Operational carbon

Operational carbon, the emissions associated with a building’s energy use in service, was rigorously assessed. While DEAP Part L typically covers only regulated loads, the MEP consultant, Waterman- Moylan, went further, using the Simplified Building Energy Model for Ireland (SBEMie), and the more comprehensive CIBSE TM54 design for performance method. This ensured a realistic prediction of both regulated and unregulated energy usage.

Key features driving operational efficiency include:

– Efficient heating and cooling: Buildings use high-efficiency heat pumps for heating.

– Natural ventilation: Prioritised with automated systems from WindowMaster in the creche and manual windows in the community centre. Only the creche’s sleeping room has a small A/C unit for temperature control.

– Renewable energy: Solar PV systems are integrated to supply 20% of the operational energy needs of each building.

Embodied carbon: The power of biogenic carbon

Sequestered carbon (biogenic carbon) in the MET elements in the creche and community centre is critical to achieving Net Zero Carbon.

The Whole Lifecycle Carbon Assessment (WLCA), funded by Construct Innovate and undertaken at the University of Galway using the IGBC Carbon Designer Tool, tracked carbon emissions across the entire life cycle of the buildings. The use of over 80 product-specific Environmental Product Declarations (EPDs) demonstrates a commitment to precise data.

The project’s whole-life embodied carbon calculations, which account for the significant sequestered carbon in the MET elements, are crucial to its success.

The final results show:

– Creche: Whole Life Embodied Carbon of 535kgCO2E/m2, dropping to 259kgCO2E/m2 when sequestered carbon is included.

• Community Centre: Whole Life Embodied Carbon of 701kgCO2E/ m2, dropping to 319kgCO2E/m2 when sequestered carbon is included.

The upfront embodied carbon for the creche and community centre represents the significant impact of using the mass timber superstructure to displace highercarbon materials such as concrete and steel.

Residual carbon and carbon offsetting

True Net Zero Carbon buildings must account for Residual Carbon of any greenhouse gas (GHG) emissions that remain after a project or organisation has implemented all technically and economically feasible opportunities, as determined by a Climate Professional as part of a carbon footprint assessment, to reduce emissions in all scopes and from all sources.

D/RES adopted the Oxford Principles for Net Zero Aligned Carbon Offsetting (2024), opting for long-term carbon removal to the biosphere.

Using the locally available Teagasc Forest Carbon Tool, D/RES have calculated that of the 14,900 trees and whips planted in the linear park adjacent to the buildings, roughly 1,350 trees would be sufficient to account for the global warming potential (GWP) emissions unaccounted for in the operational and embodied carbon calculations undertaken for the creche and community centre.

Navigating challenges: Innovation in design and certification

The journey from design to construction presented notable challenges, particularly around material selection, fire safety, and certification hurdles, highlighting the need for harmonised design guidance for MET in Ireland.

Design evolution and material substitution

Early-stage design choices significantly impacted cost and construction. The substructure, initially proposed as a suspended steel matrix, was ultimately switched to pre-manufactured concrete ground beams supported on pad foundations and concrete rising walls due to a cost uplift and detailing difficulties.

Similarly, the façade underwent revision. An initial rainscreen system with external render boards was abandoned late in the process due to subcontractor unfamiliarity and firestopping issues, which added to the costs. The final envelope uses a Baumit render application applied directly to the Naturheld wood fibre insulation, which provides a durable weather barrier as well as fire certification for the façade. While transport costs almost forced a switch to rockwool, which would have significantly increased the embodied carbon, D/RES retained the lower-carbon wood fibre.

Fire Safety and Building Control

One of the major hurdles was securing the necessary local authority approvals, including the Fire Safety Certificate (FSC) and Commencement Notice from Wicklow County Council.

– Fire Rating: The MET superstructure with its fire-rated wood fibre insulation achieved a 60-minute fire rating (RE160 in high-risk areas). The design complied with TGB – Part B (Fire Safety), relying on the predictable charring rate of CLT and Glulam.

– Certification: The local authority took a rigorous but proactive approach when assessing MET building methodology. This included a requirement for the Structural Engineering Report to integrate specific structural calculations that reflected Irish climatic conditions, ensuring the project’s long-term resilience. The authority’s initial preference for the National Standard Authority of Ireland (NSAI) Agrément certification underscored a dedication to national benchmarks. D/RES engaged in constructive dialogue, ultimately confirming the primacy and acceptability of the European Technical Assessment (ETA), Harmonised EU Standard (hEN) and CE Marking, arguing that the MET system, as a collection of structural components, aligned with these robust European mandates.

Construction challenges and lessons learned

The on-site installation of the prefabricated MET components revealed the necessity for early agreement on tolerances:

CLT Wall Base: The requirement for concrete upstands to raise the CLT walls and prevent moisture ingress was standard, but variable gaps in the in-situ concrete exceeded the allowable +/-10mm tolerance. This required modifications to the bolt fixings and the use of a high-strength structural grout.

• Lesson learned: Establishing upfront project-specific concrete tolerances and agreeing to remediation before MET installation is critical.

Glulam Base Connection: The use of fixed-height steel stanchions for the glulam columns lacked the necessary adjustability to account for thickness variability in intumescent coatings and concrete upstands.

• Lesson learned: In retrospect, an adjustable steel stanchion would have been more suitable to ensure correct positioning and structural integrity.