Sustainable Building Technical Manual - Etn-presco.net

discussion focuses on the energy input throughout the life cycle, the material and productinputs from construction through the use and operation stages, and the environmentalreleases throughout the life cycle (Figure 4). Coproducts are excluded here in theinterest of simplification; they can be included in a similar manner.The environmental impacts of the building materials and products entering the life cycleare examined in the same manner—and through the application of the same input-outputconcept—as the sequence of processes and activities that lead to or produce thosematerials. These processes begin with the acquisition of natural resources and continuethrough refining and manufacturing, including transportation, to the point when thesematerials and products are on the site, ready to be incorporated in the building. A singleprocess representing the complete sequence of processes is represented here for simplification.Figure 5 illustrates this process and the significant inputs and outputs. Expansionof this single process into its complete process sequence may be desirable depending onthe scope of the LCA. Examination of each of the other main stages in the building lifecycle can be performed in the same way and results in similar diagrams.The next stage in the assessment is developing the life-cycle inventory, which involvescollection of the data and information that characterizes the energy consumption, environmentalreleases (air, water, solids), and natural resources used in each of the mainstages and associated processes in the building life cycle.This inventory process can be carried out at varying levels of detail. The depth of theanalysis, dictated by the purpose and objectives of the project, must be clearly defined atthe beginning. It is likely, however, that a more thorough analysis will lead to greaterconfidence in the final result.For purposes of illustration, a practical and somewhat subjective approach (rather than ahighly detailed, in-depth analysis) is described here. Using the building life cycle shownin Figure 4 and taking into consideration the intended purpose and use of the building, itis possible to identify various design options, material and product choices, and buildingoperating decision, such as:■ Use of steel versus aluminum, wood, or masonry;■ Use of daylighting versus electrical solutions;■ Use of alternative glazing and window treatments;■ Design of heating, ventilating, and air-conditioning (HVAC) systems;■ Incorporation of electricity-saving devices, such as occupancy sensors and controls;■ Paint selection; and■ Flooring selection (e.g., marble versus ceramic, vinyl, or carpet).Many material and product options are available. The options will be determined by theproject itself and the many factors associated with it. It is often useful to begin with aninitial building design and examine it in terms of the building life cycle. Then, comparethis base case to an examination of other options and alternatives that are within thescope of the project.The assessment must include examination of each of the building life-cycle stages: siteselection and preparation, construction, furnishing and outfitting, use and operation,and demolition (Figure 4). The assessment begins by determining the following for eachlife-cycle stage:■ The energy input necessary to carry out each stage;■ The environmental releases and pollutants resulting from each stage; and