Share Of Embodied Energy Research Articles

On the share of embodied energy in the lifetime energy use of typical Hellenic residential buildings

The evolution of the built sector towards nearly zero energy buildings is a key issue in the global effort to reduce the greenhouse effect through the abatement of carbon emissions. For a realistic assessment of the potential for energy consumption and emissions reduction in the built sector, a life cycle approach is deemed necessary. However, the contribution of the embodied energy (EE) and related carbon emissions associated with the building lifespan from the early construction phase to its demolition has more often than not been neglected. This work contributes to the existing knowledge on the role of EE in the lifetime primary energy consumption of typical Hellenic residential buildings representing different construction types and vintages. Cradle-to-gate embodied energy coefficients for the most common construction materials have been derived through data analysis from new field surveys and published data from local manufacturing facilities in Greece and compared against international data bases using the Simapro LCA software. Complementary data from the Ecoinvent LCI database have been used where necessary. Practical EE intensities for the building envelope and the share of EE in the whole lifetime energy consumption have been derived for residential building types, taking into account common renovation measures.

Embodied versus operational energy in residential and commercial buildings: where should we focus?

We analyze 100 case studies, which were conducted in 23 countries, and contrast their data on embodied and operational energy in residential and commercial buildings. The case studies include conventional, retrofit, low-energy, passive, and net-zero energy buildings. The buildings have different lifetimes varying from 25 to 100 years. We calculate the estimated total Life Cycle Energy (LCE) as the sum of Embodied Energy (EE) and Operational Energy (OE). The LCE in the 100 case studies ranges from 50.8 to 1840 MJ/m2 per year. Our results show that operational energy significantly dominates the life cycle energy of the buildings by an average of 419 MJ/m2 per year and an average share of 72%. The share of embodied energy increases with decreasing operational energy. However, the overall LCE decreases significantly when the operational energy decreases. Naturally, the assumptions on the lifetime of the buildings have a great impact on the LCE. We conclude that operational energy should be primarily reduced in order to decrease greenhouse gas emissions from the existing building stock because most of the buildings are already built and changes in the embodied energy are often obtained only through new construction or deep retrofit strategies. Depending on the strategy to decrease OE, the share of EE was found to show wide fluctuations within the case studies, ranging from 4% up to 100%. In addition, most of the operational energy consumption has been reported by using energy simulation tools. Only about 14% of the case studies had metered operational energy data. In order to create more accurate data, metering of buildings should be considered in future case studies.