Definition
Embodied energy includes the energy consumed through the life cycle of a building as well as the energy expended for raw material extraction, the manufacturing of materials, and transportation to the construction site; the building construction, maintenance, repair, and replacement of building components during operation; and the demolition, transportation of materials, and their end-of-life management (Chastas et al., 2016). Embodied energy excludes the operational energy consumed within the building when it is in use; for example, the heating, cooling, and lighting in buildings (Moncaster & Symons, 2013). It is measured in kWh, including direct and indirect energy use, according to the CEN/TC350 standard “sustainability of construction works” (ECFS, 2019). In this chapter, embodied impact refers to the environmental impact embodied in the building, with carbon emissions representing an important measurement. Embodied emissions (EI) is the sum of fuel-related and process-related embodied emissions. Process-related embodied emissions are non-fuel related and can arise from a chemical reaction due to the building materials and assembly production (Moncaster & Symons, 2013).
Significance
The significance of embodied energy and embodied impact is reflected in three areas. First, the building and construction industry is a big energy consumer and carbon emitter; for instance, in the United States, building sectors contributed 39% of the country’s carbon emissions (USGBC, 2019a) in 2018. In the United Kingdom, the construction materials sector alone accounted for 5–6% of total UK emissions (Rawlinson, 2007). Although emissions from the global building sector have leveled off since 2015, overall, building construction and operations still accounted for 36% of global final energy use and nearly 40% of energy-related carbon emissions in 2017 (2018 Global Status Report, 2018) as new construction and existing building renovation projects are energy-intensive (United Nations Environmental Programme-Sustainable Buildings and Climate Initiative, 2008; H.M. Government, Innovation and Growth team, 2010).
Second, operational energy saving could potentially be lost through sub-optimal management or an accelerated refurbishment cycle (USGBC, 2019b), meaning a shorter building use life span leads to quicker retrofit cycles, resulting in increased total embodied energy and embodied emissions. Therefore, more attention should be focused on embodied emissions embedded in renovation materials and components.
Lastly, savings in embodied emissions can effectively reduce the overall carbon emissions; however, the emissions reduction goal cannot be achieved through increasing operational emission savings alone (USGBC, 2019b; Dixit et al., 2010; Acuqaye, 2010). These three areas suggest that building designers can greatly influence the carbon footprint of buildings (Brummer et al., 2008), as designers and architects have the most control over the embodied energy used in buildings. Any initiative that is focused on reducing such embodied energy and embodied impact will significantly contribute to meeting energy reduction targets (Dowden, 2008).