Mathematical modelling of embodied carbon emissions of building projects

It is increasingly recognised that if the emphasis remains on reducing operating carbon emissions (OC) of buildings, embodied carbon emissions (EC) will eventually attain a significant proportion of buildings' lifetime carbon emissions (LC). Emphasis on minimising EC is equally desirable if LC is to be reduced. A first step to minimising EC is quantification, in order to know what quantities to minimise. However, several prevalent approaches of quantifying EC pose challenges in promoting potential alternative actions to reduce EC. In many cases, besides the limitations associated with the boundaries usually adopted, it is difficult (if not impossible), to attribute the respective sources of energy (e.g. diesel, coal, biomass etc.) to the resulting EC. This paper presents a mathematical model for computing EC of building projects and in contrast to previous studies, a concept of disaggregation is adopted in order to identify EC with the respective energy sources. The approach enables the specific sources of energy to bear on the quantification of EC, in a manner that allows differentiation of the contribution of the different sources of energy. The model is presented in a series of mathematical equations. The major benefit associated with the nature of the developed model is that, even without recourse to material substitution (e.g. timber for concrete), it is possible to achieve emission reductions from the same material by optimising the parameters (e.g. energy used in manufacturing and transportation) associated with its EC.