Structural engineers are now expected to consider the environmental impacts of their designs, alongside the more traditional performance measures of strength, safety, serviceability and cost. Life cycle assessment (LCA) is a tool to analyze the environmental impacts of a building, from construction to end-of-life; thereby identifying ways to reduce those impacts. The application of LCA to the complex, inter-related nature of buildings represents a significant challenge and the field continues to develop rapidly. Nevertheless, LCA is becoming an important tool in the building design industry, and structural engineers need to be conversant in the basics of LCA. This paper will introduce fundamental concepts of LCA of buildings allowing structural engineers tobecome more involved in the sustainable building design process.  These processes are upheld by structural engineering companies in New Jersey and throughout the United States as standards to abide by. 

The goal of LCA is to compare the full range of environmental and social damages assignable to products and services, to be able to choose the least burdensome one. At present it is a way to account for the effects of the cascade of technologies responsible for goods and services. It is limited to that, though, because the similar cascade of impacts from the commerce responsible for goods and services is unaccountable because what people do with money is unrecorded. As a consequence LCA succeeds in accurately measuring the impacts of the technology used for delivering products, but not the whole impact of making the economic choice of using it.

The term 'life cycle' refers to the notion that a fair, holistic assessment requires the assessment of raw material production, manufacture, distribution, use and disposal including all intervening transportation steps necessary or caused by the product's existence. The sum of all those steps – or phases – is the life cycle of the product. The concept also can be used to optimize the environmental performance of a single product (ecodesign) or to optimize the environmental performance of a company.

Common categories of assessed damages are global warming (greenhouse gases), acidification (soil and ocean), smog, ozone layer depletion, eutrophication, eco-toxicological and human-toxicological pollutants, habitat destruction, desertification, land use as well as depletion of minerals and fossil fuels.

In order to make efficient use of time and resources and outline how the study will be conducted and what final results will be obtained, the following six decisions must be made at the beginning of the LCA process:

(1) Define the goal(s) of the project

(2) Determine what type of information is needed to inform the decision-makers

(3) determine the required specificity

(4) Determine how the data should be organized and the results displayed

(5) Define the scope of the study

(6) Determine the ground rules for performing the work.

In the first phase, the LCA-practitioner formulates and specifies the goal and scope of study in relation to the intended application. The object of study is described in terms of a so-called functional unit. Apart from describing the functional unit, the goal and scope should address the overall approach used to establish the system boundaries. The system boundary determines which unit processes are included in the LCA and must reflect the goal of the study. In recent years, two additional approaches to system delimitation have emerged. These are often referred to as ‘consequential’ modeling and ‘attributional’ modeling. Finally the goal and scope phase includes a description of the method applied for assessing potential environmental impacts and which impact categories that are included.