Embodied Energy Team






‘Process analysis’ is currently the most common approach used. It typically provides the most reliable information, based on physical quantities of energy, emissions or other environmental flows obtained from specific manufacturers or service providers. However a large proportion of environmental flows are often excluded due to difficulties in obtaining data on particular processes, especially those further upstream in the supply chain or not related to the main materials used within a building (for example, the energy required to operate the buildings housing the financial institutions that provide finance to materials manufacturers -  these services, as well as many others, are essential for the operation of the business).
 
Most commercially available tools for conducting building life cycle assessments rely on data obtained using a process analysis. While this process may not have a systemically complete consideration of the performance of a building or specific material, it can often be acceptable for some types of studies. For example, comparative studies, where two competing building designs or materials are being compared may not differ substantially in terms of relative findings between choices even if a more comprehensive approach had been used.
 
Information on the environmental flows (inputs of energy, water and raw materials and outputs of waste, pollutants and emissions) associated with the processes typically excluded in a process analysis can be obtained using methods that rely on economic data. This alternative approach, typically referred to as ‘input-output analysis’, relies on national statistics that trace monetary transactions between each sector of the economy. While often less reliable than process data, its use ensures that every environmental flow associated with the construction of a building is accounted for.
 
In order to capture the strengths of both process analysis (reliability) and input-output analysis (comprehensiveness) and minimise their inherent limitations, a hybrid approach, where input-output data is used to fill any gaps in available process data, can be used. While process analysis and input-output analysis can be used to gain an initial indication of the performance of a product in order to better target improvement efforts or identify potential options, more detailed studies should consider a hybrid approach. This is to ensure that all environmental flows are accounted for and strategies for environmental improvement are being targeted at the most important processes.