Ressourceforbrug på byggepladsen: Klimapåvirkning af bygningers udførelsesfase

This report aims at developing quantitative key figures and reporting criteria for implementing the building process stage in the whole-life carbon requirements of the Danish building regulations. In January 2023 mandatory carbon limits for new buildings were introduced. The limit value and, if necessary, method will be revised in 2025, 2027 and 2029 to secure an effective mitigation of carbon in new buildings according to the national strategy for sustainable construction and to prepare the Danish building sector for the expected introduction of EU-wide carbon regulation in the Building Directive revision.
Current Danish carbon regulation includes the stages Product (modules A1, A2, A3), Replacement (B4), Operational energy use (B6), End-of-Life (C3, C4) and processes beyond the project (D). The construction process encompassing Transport to site (A4) and Installation (A5), is not part of the current requirements due to a lack of data, a harmonised approach and practical experience in Denmark.
In a first step, the methodology for A4 and A5 according to international standards is mapped and analysed. Few countries have already adopted A4 and A5 in current or planned regulation. These varying requirements are collected and analysed too. Expanding the current scope with transport and installation will introduce new sorts of processes and the need for a greater engagement of contractors and suppliers and, not at least, new types of data. International legislation shows different approaches to adjust the scope of included processes, reporting information and the degree of allowed standard values, all of which attempt to meet regional circumstances. Differences root in the general approach to building carbon regulation, consultancy, and construction practices, but also in varying conditions of geography, geology, or climate.
Concluding the method development, an approach is chosen, where all processes in both modules is included in the analysis and subsequent regulation as a rule. The only omitted processes are water use and losses during transportation. Since some of the necessary data will not be available under feasible conditions, a set of standard values are developed. The legislator can use them as an instrument for simplifying reporting effort during the implementation stage.
The study of carbon emissions related to transport to the site is conducted in two steps. The first includes developing average emissions for building product groups, based on an analysis of 90 environmental product declarations (EPD). These standard emission factors were then applied to assess emissions in 9 selected building cases of varying building types and uses. The resulting median for module A4 is 0,4 kgCO2e/m2y.
Installation processes include the use of electricity, heating energy, fuel and construction waste. Also, transport on and from the site is included. The analysis is based on monitoring data from 52 construction sites and takes the larger expected share of renewable energy in 2025 into account. Construction waste has the largest share in A5 with 38%. The resulting median for module A5 of 1,0 kgCO2e/m2y.
The total construction process including both modules equals 1,4 kgCO2e/m2y or 13% of the total emissions in new buildings, when using a 9,5 kgCO2e/m2y reference for modules A1-3, B4, B6 and C3-4.
This report is a result of the project Ressourceforbrug på byggepladsen, which BUILD is conducting between 2021-2024 on commission by the Danish Authority of Social Services and Housing.