Modelling the Environmental and Financial Performance of Construction

Professor Craig Langston- ARC Linkage Project

Bond University partnered an Australian Research Council (ARC) Linkage Project into Modelling the Environmental and Financial Performance of Construction. Other partners were The University of Melbourne (host institution), Deakin University and Williams Boag Architects. The research comprised $178,000 of funding from the ARC and about $60,000 of funding from the industry partners (plus in-kind support) over three years, and concluded in 2009. One of the chief investigators on the project was Dr Craig Langston, Professor of Construction and Facilities Management in the Mirvac School of Sustainable Development at Bond University.

The research focused on the link between construction cost and embodied energy and concluded that, where recycling and reuse were not dominant design strategies, that initial construction cost and embodied energy were highly correlated and depicted a positive linear relationship irrespective of building size. This aspect of the project investigated thirty case study buildings in Melbourne that reflected a “business as usual” approach, despite their diverse functional typologies. The key lesson from the research was that increased emphasis should be placed on embodied energy optimisation rather than just operating energy performance, and that where construction cost was minimised through clever design, small footprint/scale, less complexity and appropriate choice of materials and systems, embodied energy was similarly reduced.

Embodied energy is defined as all of the upstream energy processes involved in the construction of buildings, such as resource extraction, manufacturing of materials, packaging, transportation and construction on site. Often treated as a hidden element of overall energy demand, it is vitally important to our industry as it contributes to the climate change impacts resulting from new development. It has been said that the greenest buildings are the ones we already have. The effect of embodied energy is even more influential on buildings that have short useful lives. Long life and low energy forms a powerful alliance.

The research objective was to discover the nature of the energy-cost relationship and other related heuristic rules by performing a thorough statistical analysis of the created dataset. This analysis included both initial and recurrent energy and cost considerations. Through a series of regression analyses, energy and cost were shown to have a high correlation, to the extent where an inherent relationship can be confidently claimed. While a dependency between energy and area, or between cost and area, has been shown to exist, after elimination of GFA using energy and cost residuals a strong correlation remained. The r2 value for total project energy and total project cost was 0.5959. The r2 value for embodied energy and capital cost was 0.7081. Furthermore, the r2 value for operating energy and operating cost was 0.6264.

The overall relationship between embodied energy and capital cost can lead to the development of predictive models for energy based on cost. For example, embodied energy is given by the regression line y=0.0071x, where energy (y) is expressed in GJ and cost (x) is expressed in fourth quarter 2006 dollars. In this case it is therefore possible, by calculating construction cost (excluding contingencies, professional fees, land acquisition costs and goods and services tax), to derive embodied energy (including direct and indirect energy flows) at the project level.

But it should be remembered that this research was based on thirty ‘ordinary’ buildings. They had no special significance in terms of environmental performance or efficiency. They are representative of probably 90% of the existing commercial building stock in our cities. The challenge from this research, therefore, lies in trying to break the inherent energy-cost relationship by finding ways to minimise energy for new development even though the cost may have to rise. The heuristics promoted in this research apply where we make no effort to introduce improvements through innovation and better environmental design but rather follow traditional paradigms. Our ability to redefine the energy-cost relationship will ultimately be our success in realising more sustainable development.

This research has led to a successful doctoral thesis and a number of international journal papers and conference presentations. It drew on earlier work by the team in the development of SIFT and SINDEX software and its validation. The latter is freeware available via the Australian Institute of Quantity Surveyors or from Dr Craig Langston directly. Further information on SINDEX is available here.

Bond University is privileged to have been involved in this research. New knowledge from this and other ARC projects is being integrated back into the curriculum for undergraduate and postgraduate study. Through this process it is hoped that Bond University graduates are able to take their place in the construction, facilities management, property and urban development industries to help achieve better and more sustainable outcomes for our world.

For further information concerning this research, click here.