Greener Designs of Buildings using the Structural Sustainability Index

Sustainability is a concern that must also be addressed by structural engineers. Structural engineers must be able to discriminate as to which materials and processes would have a lesser impact to the environment, and to coordinate with the other stakeholders of the structure. The concept of the study is to enable the structural engineer to analyse the sustainability of structural systems in a quantifiable manner. 

In designing a house, or any structure, there are three things commonly considered by the structural engineer. Namely: safety, serviceability and cost. Safety and serviceability ensure that the structure can fulfill its intended purpose by satisfying code requirements on strength, ductility and deflections. Addressing economy, on the other hand, requires value engineering to produce an optimum design with reasonable cost. There is now an increasing concern about the environmental impact of structures. Sustainable design of houses must be pursued to address this concern. But what parameter may be used to guide structural designers to make their structures “greener”?

In an undergraduate thesis, the environmental impact of the structural systems and envelope of selected housing units for a middle class family in the Philippines using Life Cycle Analysis (LCA) was conducted.  The five environmental impact parameters: (a) Global Warming Potential, (b) Ocean Acidification, (c) Abiotic Material Depletion, (d) Energy Use, (e) Human Toxicity were assessed considering the manufacturing and disposal stage as the system boundary in the LCA study. A  “Structural Sustainability Index” or SSI which produces a single score aggregating the five impacts was derived by assigning weights based on an expert’s survey for each environmental impact indicator. The SSI can be used for ranking houses based on environmental impact and can be used as a parameter to guide structural engineers in comparing various design alternatives and selecting  “greener designs”.

The image below is a poster submitted to the ASEP Student Research Competition during the 16th ASEP International Conference held on May 23-25, 2013.