Buildings are directly responsible for 40% of the final energy use in most developed economies and for much more if indirect requirements are considered. This results in huge impacts which affect the environmental balance of our planet.

However, most current building energy assessments focus solely on operational energy overlooking other energy uses such as embodied and transport energy. Embodied energy comprises the energy requirements for building materials production, construction and replacement. Transport energy represents the amount of energy required for the mobility of building users. Decisions based on partial assessments might result in an increased energy demand during other life cycle stages or at different scales of the built environment. Recent studies have shown that embodied and transport energy demands often account for more than half of the total lifecycle energy demand of residential buildings. Current assessment tools and policies therefore overlook more than 50% of the life cycle energy use.

This research has developed a comprehensive life cycle energy analysis framework for residential buildings. This framework takes into account energy requirements at the building scale, i.e. the embodied and operational energy demands, and at the city scale, i.e. the embodied energy of nearby infrastructures and the transport energy of its users. This framework is implemented through the development, verification and validation of an advanced software tool which allows the rapid analysis of the life cycle energy demand of residential buildings and districts. Two case studies, located in Brussels, Belgium and Melbourne, Australia, are used to investigate the potential of the developed framework.

Results show that each of the embodied, operational and transport energy requirements represent a significant share of the total energy requirements and associated greenhouse gas emissions of a residential building, over its useful life. The use of the developed tool will allow building designers, town planners and policy makers to reduce the energy demand and greenhouse gas emissions of residential buildings by selecting measures that result in overall savings. This will ultimately contribute to reducing the environmental impact of the built environment.

The research was conducted as a joint-PhD between the Université Libre de Bruxelles and the University of Melbourne.

This research was funded by:
– The Belgian National Fund for Scientific Research F.R.S.-FNRS
– Wallonia Brussels International excellency scholarship
– BRIC scholarship

Selected Publications:
[1] Stephan, A., Crawford, R.H. and de Myttenaere, K. (2013) A comprehensive assessment of the life cycle energy demand of passive houses. Applied Energy 112 (0):23-34.
[2] Stephan, A., Crawford, R.H. and de Myttenaere, K. (2013) Multi-scale life cycle energy analysis of a low-density suburban neighbourhood in Melbourne, Australia. Building and Environment 68 (0):35-49.
[3] Stephan, A. and Crawford, R.H. (2013) A multi-scale life-cycle energy and greenhouse-gas emissions analysis model for residential buildings. Architectural Science Review:1-10.
[4] Stephan A, Crawford RH, de Myttenaere K. Towards a comprehensive life cycle energy analysis framework for residential buildings. Energy and Buildings. 2012;55:592-600.
[5] Stephan, A., Crawford, R. H., and de Myttenaere, K. (2011). Towards a more holistic approach to reducing the energy demand of dwellings. Procedia Engineering, 21(0), 1033-1041.

Thesis
Stephan, A. (2013) Towards a comprehensive energy assessment of residential buildings. A multi-scale life cycle energy analysis framework.

General Press
Stephan, A., Crawford, R.H. (2013) Why energy-saving homes often use more energy. The Conversation.
Stephan, A. (2013) Pourquoi la PEB ne suffit pas? La PEB en question. Leonardi, P (2012) Un outil pour optimiser les économies d’énergie. Le Soir. Immo (19/01/2012)