Environmental benchmarks for residential buildings in Belgium based on a hybrid LCI and modelling approach

This joint PhD project is based at KU Leuven with a minimum 12 month stay at The University of Melbourne.

Project description
Buildings and cities contribute significantly to global environmental issues, including greenhouse gas emissions, resource depletion, waste and pollution. Life cycle assessment (LCA) enables assessment and optimization of the environmental impact of buildings over their entire life cycle. In Belgium, various steps have been taken to integrate LCA in building practice: a national LCA method has been developed, a national database is established with specific data for Belgian construction products, and a web-based calculation tool was launched in 2018. Environmental benchmarks, as point(s) of reference against which any comparison can be made, are still lacking to date and are seen as an important next step to support policy makers in the definition of environmental targets for buildings.

In the building sector, operational energy use benchmarks have been introduced in all EU member states in the context of the European Directive on the Energy Performance of Buildings (EPB). In contrast to energy benchmarks, only a limited number of EU countries have defined broader environmental benchmarks for buildings. Since 2018, the life cycle environmental impact of new buildings in the Netherlands is restricted to a maximum value per m² floor area and classes of environmental performance of residential buildings have been defined. In France a voluntary labelling system “E+/C-“ exists and Switzerland has defined a benchmark within the initiative of the “2000 Watt Society”. LCA benchmarks are furthermore integrated in sustainability certification schemes such as BREEAM, DGNB and LEED.

The aim of this doctoral research is to define environmental benchmarks for residential buildings in Belgium considering their whole life cycle. Benchmarks can be defined in various ways related to the goal of the benchmark. The aim of this project is to define four types of benchmarks. First, a long term target will be defined, representing the maximum impact the construction sector may cause to remain with the carrying capacity of the Earth regarding environmental loads. Second, in order to understand the environmental performance of current buildings (both existing and new ones), an LCA study of the existing stock will be performed. Based on a statistical analysis of the results, limit values (worst performance), reference values (average performance) and best-practice values (best performance) will be defined. For the calculation of the environmental impact of the existing stock, data on the embodied environmental flows of construction materials are needed (besides data on operational flows). These data are available in various forms, including life cycle inventory (LCI) databases and Environmental Product Declarations (EPDs). However, the majority of these data sources suffer from system boundary truncation, which means that a large proportion of the embodied emissions, energy, water etc. associated with the production of these materials are unaccounted for. This results from the complexity and time intensive nature of bottom-up data collection. Therefore, our existing understanding of the true impact of the use of construction materials on the environment is limited. A hybrid approach to the compilation of embodied environmental flow data for materials uses a top-down approach and macro-economic data to address this issue and fill in any data gaps. To ensure consistency between the values obtained through both approaches, hybrid life cycle inventory modelling, developed at The University of Melbourne, will be used for the bottom-up models.

The objectives of the first project are the following:

  1. Development of a methodology for environmental benchmarks
  2. Modelling environmental benchmarks using a top-down approach
  3. Modelling environmental benchmarks using a bottom-up approach
  4. Comparison of benchmarks based on top-down and bottom-up approaches
  5. Dissemination of research findings

The project will be complemented by the project on EPiC Europe: a construction material environmental flow database for Europe and the collaboration will ensure a successful completion of the project

Supervision team:

Principal Investigators (PIs)

Associate Professor Dr Karen Allacker (KU Leuven)
Associate Professor Robert Crawford (The University of Melbourne)

Co-Principal Investigators (co-PIs)

Dr André Stephan (Université Catholique de Louvain, Belgium)