Environmental impacts of on-site construction processes: Focus on structural frames.

摘要

Buildings and their construction are material- and energy-intensive and can cause significant environmental emissions and waste. Even though consumption is large, construction material resources appear to be consumed at a sustainable rate. The same cannot be said for energy resources which are consumed throughout the stages of a material's life-cycle. In the U.S., petroleum is being used at an unsustainable rate. Through the use of extended producer responsibility (EPR), construction materials can be reused and recycled to reduce materials and, therefore, energy use. To know the materials on which to focus EPR efforts for reuse and recycling, the total life-cycle environmental impacts must be known. This can be achieved through the use of life-cycle assessment (LCA). I analyzed the overall life-cycle impacts of three commercial buildings and while the building use phase tends to dominate most emissions studied, the manufacturing of materials for construction and maintenance can also be significant causes of emissions and energy use. The waste and emissions from constructing concrete structural building frames are larger than those for constructing steel frames, but steel frames tend to have larger emissions due to material extraction and manufacturing. In terms of overall life-cycle emissions and energy use, steel frame buildings are similar to concrete frame buildings. I created the Construction Environmental Decision Support Tool (CEDST) to determine the energy use and emissions during the construction process of steel and concrete building frames. With the framework for the construction phase environmental decision support tool established, the CEDST can be expanded to include all construction processes. This allows for the comparison and improvement of different building designs as well as different construction processes. The output of the CEDST can be used as input for the construction phase impacts in an overall building LCA.