Assessing embodied energy of building structural elements

Although operational energy is currently the focal point of sustainability in building regulations, embodied energy and carbon dioxide emissions will become more significant as operational energy consumption is reduced. In the near future, embodied energy could account for a significant proportion of a building's carbon footprint over its lifetime, bearing in mind that the construction of energy-efficient buildings is carbon and energy intensive. Unlike operational energy, embodied energy savings have an immediate significant effect on carbon footprint and are independent of human behaviour. However, there is a lack of consensus within the construction industry on how to assess embodied energy and carbon dioxide and where to draw system boundaries, which has impeded advancement on the issue. This paper analyses the life-cycle embodied energy and carbon dioxide emissions of a building's structural elements, and examines which stages within a building's life are the most significant and offer the most opportunities for a reduction of embodied energy and carbon dioxide. The embodied energy and associated carbon dioxide at the product and construction, maintenance and end-of-life stages of a structure are examined, as well as the potential for energy recovery and carbon dioxide offsetting. A simple single-storey structure is used as a case study to perform comparative analyses between two structural design alternatives: glue-laminated timber panels and steel frame with infill concrete blockwork.