Roadstone blacktop optimisation: designing for energy efficiency and carbon reduction with EXEED
Through SEAI’s EXEED Certified Energy Efficient Design approach, Roadstone optimised its blacktop production process, reducing energy use and emissions while boosting operational performance across its asphalt plants.
Background
Roadstone, a leading supplier of building and construction materials, operates multiple blacktop (asphalt) production plants nationwide. As part of its commitment to sustainability and corporate decarbonisation goals, Roadstone identified a major opportunity to improve the energy performance of its blacktop operations, which are energy-intensive due to the heating and drying of aggregates and bitumen. Part of the CRH Group, Roadstone implemented group-wide energy and resource efficiency programmes to help achieve a more energy-efficient, resilient, and sustainable built environment.
Since 2007, Roadstone has implemented structured energy management across its operations. 22 Roadstone locations throughout the country, including ‘The National Transport Division’, and are accredited to ISO. 50001 - the internationally recognised Energy Management Systems standard.
Roadstone partnered with SEAI under the EXEED (Excellence in Energy Efficient Design) certified programme to apply structured design thinking from the earliest project stages. The objective was to integrate energy efficiency, carbon reduction, and cost savings into plant operation and future investment planning. Roadstone uses the EXEED approach to highlight and implement energy efficiency measures that may not be identified under normal business practices.
The project
In 2016, SEAI introduced the EXEED process to Roadstone. As part of the IS. 399 approach, several opportunities were identified as having the potential to save energy within the business production process.
These opportunities were identified in the Energy Balance Study (EBS), analysed in the Challenge and Analyse (C&A) stage and recorded in the Energy Savings Register (ESR) - key documents in the EXEED process. Improvement projects were discussed further and the most appropriate were included in a Project Execution Plan (PEP) delivered by the in-house EXEED Project Team.
The analysis of Roadstone's business activities quickly identified the asphalt process as a significant energy user (SEU). An energy balance report for Roadstone's production activities showed that in 2018 asphalt production accounted for around 40% of Roadstone's total annual energy use i.e., approximately 160 GWh. Therefore, asphalt production became the focus of the initial EED project.
Asphalt production
Asphalt is used in building transport infrastructure, including roads, car parks and runways. The asphalt production process is carried out across multiple Roadstone locations.
The IS. 399 approach for optimising the production of each asphalt producing site is broken into two stages. The first stage was listed in the Energy Savings Register. It involved implementing control measures that regulate input temperatures, including dryer modifications. Aggregates used in the manufacture of Asphalt need to be heated to elevated temperatures to remove all moisture in the raw material. These heated aggregates are then mixed with bitumen and other components to produce Asphalt mixtures.
Dryer modifications and upgraded controls allow Roadstone to reduce fuel consumption by creating an optimised heating and drying environment. It also increases the possibility of adding reclaimed asphalt material that would normally be sent to landfill, therefore increasing the circularity of the product.
The second stage (or opportunity) involved using data and intelligent software that will build algorithms that communicate issues that are affecting performance within the production process. The IS. 399 process identified that accurate energy and plant performance data makes it easier to demonstrate and quantify the viability of the application of renewable energy solutions.
The Blacktop Optimisation EXEED Project focused on reviewing and redesigning the core energy systems within Roadstone’s asphalt production process.
Targeted Interventions
Using SEAI’s EXEED - Excellence in Energy Efficient Design and I.S. 399 methodology, Roadstone and its energy consultants conducted detailed assessments of heat flows, combustion efficiency, and electrical demand across the plant. This analysis informed targeted interventions, including:
- Optimising burner systems for higher combustion efficiency and lower fuel use.
- Enhancing thermal insulation of dryers and bitumen storage tanks to minimise heat losses.
- Installing variable speed drives (VSDs) and advanced process control systems for better load matching and energy management.
- Upgrading automation and monitoring to continuously measure energy use and performance indicators (EnPIs).
- Exploring process adjustments to increase reclaimed asphalt use, reducing virgin material demand and embodied carbon.
- Enhancing raw material handling and storage facilities that minimise moisture ingress.
By embedding energy efficiency into the design, rather than retrofitting, Roadstone maximised the lifecycle performance and ensured each design decision considered long-term energy and cost impacts.
For Roadstone Limited, EXEED has become more a way of routinely managing the entire production aspects of the company, not just energy management aspects.
Results
The project delivered clear, measurable outcomes aligned with SEAI’s EXEED objectives and Ireland’s Climate Action Plan targets.
Performance Highlights:
| Indicator | Baseline | Post-Project | Outcome / Improvement |
| Energy intensity use per tonne (kWh/t) | 125 kWh/t | 90 kWh/t | 28% reduction |
| Annual CO₂ emissions | 49,200 tCO₂e | 35,000 tCO₂e | ~14,200 tCO₂e saved annually |
| Payback period | — | — | 4.5 years (for all projects) |
| EXEED Certification | Stage 2 Capital Investment | EXEED Managed Certified | The EXEED Plaque was presented in September 2025 to Roadstone |
Key Achievements
- Reduced plant thermal energy demand and improved overall system efficiency.
- Reduced operational costs.
- Lowered direct (Scope 1) fossil fuel emissions.
- Improved control and monitoring for continuous performance tracking.
- Enhanced staff awareness and energy management culture.
- Established a replicable design model for other Roadstone asphalt plants.
- Lower temperature mixes with two hot wrap systems.
What's next?
To date, 10 of the 11 Roadstone asphalt producing sites are now upgraded and completed. There are currently 9 sites undergoing EXEED certification audits, with the last remaining site is due to be completed by 2030. Part of a 10-year investment programme strategy to implement the IS. 399 process for all products, including the asphalt plants and other opportunities identified in the Energy Savings Register by this EXEED project, which provided significant added value, innovation, as well as energy and carbon savings targets.
Roadstone is now sharing the lessons learned and design approach with other asphalt producers and expanding the Energy Efficient Design (EED) approach to new and refurbished sites, integrating ISO. 50001 energy management systems with the EXEED Managed Certified design processes for ongoing improvement and increasing use of low-carbon fuels and recycled materials.
These actions support Roadstone’s goal to align fully with the Climate Action Plan and Ireland’s 2030 industrial decarbonisation targets.
Roadstone also collaborates closely with industry partners including Transport Infrastructure Ireland (TII), the Department of Transport and local authorities on the development of low CO2e Road Pavement solutions. This has resulted in changes to material specifications that now facilitate the use of lower CO2e Asphalt solutions. TII has also recently indicated the provision for EPD’s for Asphalt materials will be mandatory from 2026. Roadstone recently published Asphalt EPD’s for all Asphalt Plants in support of this specification change.
Roadstone are the first business in Ireland to achieve Level 5 Certification on the CO2 Performance ladder. These changes are built on strong foundations that ISO 50001 has given the business and the supports and advice provided by SEAI.
Learn how your organisation can design for energy efficiency and decarbonisation with SEAI’s EXEED programme.
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