Dr. Oliver Kinnane:

I thank the committee for inviting me to present. The building in a climate emergency research group at UCD is undertaking a comprehensive modelling study of the Irish built environment and construction sector, baselining current activity and projecting emissions out to 2030 and 2050. The evidence I give today is primarily derived from that research and from projects funded by the Sustainable Energy Authority of Ireland, SEAI, and the European Commission, all focused on achieving a more sustainable built environment.

Through our modelling work we have shown that the construction and operation of the Irish built environment accounts for 23 megatonnes of CO2 emissions annually, a 37% share of all emissions. This is split two to one between the operation and construction of the built environment. The built environment is growing. Considerable construction across all sectors is planned from now to 2030. This growth in our built environment will bring significant additional operational and embodied emissions in the short time horizon to 2030. Our model highlights the challenge to reduce operational emissions by 51%. The only scenario where we achieve this reduction in operational carbon by 2030 is one where: the national retrofit plan is implemented in its entirety; renewable energy rises to 80%; and significant changes in user behaviour to further increase the efficiency of buildings in use occur. Improvement in embodied emissions, although not bound by the same targets, will be even more difficult. We baseline today’s emissions at approximately 9 megatonnes of CO2, and if construction grows as outlined in the national development plan, NDP, with no change in the carbon intensity of construction, our model shows embodied emissions rising to over twice that total by 2030.

It is essential that we enhance the performance of the current building stock. Retrofit of 500,000 homes to a B2 standard or better can reduce emissions by 2 megatonnes of CO2 by 2030 if aligned with significant improvement in the carbon intensity of the electricity supply. Current retrofit rates are well below the levels required, however. Among other barriers, necessary knowledge and skills are lacking across the design and construction industry. Through projects we have undertaken for the SEAI we have identified a performance gap between house retrofits to a nearly zero energy building, NZEB, standard and actual performance. In some cases, A-rated homes are performing at C levels. Approximately 50% of fabrics are not meeting design U-values and heat pumps are underperforming, often due to improper installation. It is important we get retrofit right to avoid retrofitting the retrofit in ten years' time.

Embodied emissions in construction will grow to 2030 as construction grows.

It is not regulated and measurement is currently not mandated, even though these emissions represent 14% of our national emissions. Concrete represents more than 90% of our building material-related national production emissions. Innovations in the cement industry can reduce this considerably. Savings of up to 50%, or more, are possible. We estimate that a low-clinker, low-carbon concrete could cut 15% to 20% off the annual embodied carbon cost of our own national development. Bio-based materials are a solution but uptake is low and skills and production facilities are lacking. No processing facility exists for hemp, for example, and building regulations restrict their potential use.

We have some of the highest rates of vacancy in Europe. Our model shows that retrofitting 100,000 of our vacant homes could slice 1 MtCO2e off an embodied carbon bill of 4 to 5 MtCO2e for the 400,000 new homes proposed in the national development plan. We are constructing many new buildings but we are also demolishing buildings to make way for replacement buildings. Young buildings, built only 30 to 40 years ago, are being torn down all over the city to be replaced by buildings of much greater floor area and materials of high embodied carbon. The service life of buildings is constantly decreasing. This is unsustainable. We need to save the buildings we have and retrofit first.

On recycling and reuse of materials, we need to circularise our construction economy. Construction and demolition waste is thought to be the fastest-growing waste stream in the country and up to 10 megatonnes annually is expected in the coming years. This needs to be repurposed. We need to get creative with our waste reuse. As an example, our research group is doing a project with industry to replace up to 20% of cement in concrete with ground glass from recycled glass bottle waste.

We can achieve our ambitious targets but much work is required. A whole-life carbon perspective of the built environment is necessary. We can achieve considerable emission savings through retrofit but embodied emissions are growing and need to be measured, regulated and reduced. Higher education will play an important role. Research funding is critical to allow us to work alongside industry. We need to adapt curricula to respond to the knowledge and skills shortage.