Embodied Energy Assessment Research Articles

Embodied energy assessment for ecological wastewater treatment by a constructed wetland

Embodied energy as the energy supplied directly and indirectly through input pathways by human society is analyzed for a constructed wetland as a typical ecological engineering. The method of systems accounting as a combination of process and input–output analyses in context of systems ecology is introduced to account the embodied energy as one of the most important ecological indicators of constructed wetland. Based on the latest embodied energy intensity database for the Chinese economy 2007, the embodied energy of a typical constructed wetland in both the construction and operation stages is accounted and compared with those for a cyclic activated sludge plant as a typical conventional wastewater treatment system and a hybrid system of conventional wastewater treatment system and constructed wetland. The indirect energy is revealed to be more important than the on-site direct energy, which accounts for only 30–40% of the total. The energy embodied in the five terms of treating per m3 wastewater and removing per kg BOD, COD, SS, and NH3-N by the constructed wetland is only 6.83%, 17.48%, 13.96%, 22.47% and 9.48% of that by the conventional system, and 9.51%, 38.26%, 27.01%, 39.42% and 13.20% of that by the hybrid system, respectively. The ecological engineering of the constructed wetland is illustrated more favorable than the conventional wastewater treatment due to its considerable ecological benefit.

A comprehensive framework for assessing the life-cycle energy of building construction assemblies

Building environmental design typically focuses on improvements to operational efficiencies such as building thermal performance and system efficiency. Often the impacts occurring across the other stages of a building's life are not considered or are seen as insignificant in comparison. However, previous research shows that embodied impacts can be just as important. There is limited consistent and comprehensive information available for building designers to make informed decisions in this area. Often the information that is available is from disparate sources, which makes comparison of alternative solutions unreliable. It is also important to ensure that strategies to reduce environmental impacts from one life cycle stage do not come at the expense of an increase in overall life-cycle impacts. A consistent and comprehensive framework for assessing and specifying building assemblies for enhanced environmental outcomes does not currently exist. This article presents the initial findings of a project that aims to establish a database of life cycle energy requirements for a broad range of construction assemblies, based on a comprehensive assessment framework. Life cycle energy requirements have been calculated for eight residential construction assemblies integrating an innovative embodied energy assessment technique with thermal performance modelling and ranked according to their performance.