Process LCA is what most people think of when they hear of life cycle analysis. Process LCA maps the flows of materials through processes (mining, smelting, refining, extruding, transporting, etc.) and assigns resource flows and pollutant releases to each. EPA's WARM tool and MSW DST, and Environment Canada's GHG Calculator for GHG Management, are all derived from process LCAs of manufacturing products from virgin and recycled feedstocks, and end-of-life processes such as composting, incineration, and landfilling.
In most cases, off-the-shelf tools such as WARM will serve the needs of state and local governments, particularly when it comes to estimating the GHG emissions reductions or reduction potential of many prevention, recycling, and composting activities. Occasionally, however, special questions will arise regarding management methods or materials that have not been documented elsewhere. For example, WARM uses an average for all carpet. A green building program focusing on purchasing guidelines might want to know more about different types of carpet, such as Nylon-6 vs. Nylon-6,6 vs. wool. To answer these types of more detailed questions, process LCAs should be considered.
The greatest limitation of process LCAs are that they tend to be expensive and time consuming. However, the information gained from process LCAs are often very valuable.
A few examples of process LCAs that have been commissioned by state and local governments, with a focus on materials management, are provided here.
- LCA of E-Commerce Order Fulfillment Shipping Options. This study evaluated the environmental burdens of different options for shipping non-breakable items in an e-commerce/catalog order fulfillment environment. It demonstrates the importance of waste prevention, and shows that when comparing dissimilar materials, recyclability and recycled content don't always correlate to reduced environmental impacts.
- LCA of Water Delivery Options. This study compares the environmental impacts of different methods of delivering drinking water to households, including single use bottles (recyclable and/or compostable) and tap water methods. The study provides a lot of information about the impacts and benefits of different resin choices and end-of-life management methods. A supplemental report demonstrates the moderate benefits from recycling single-use PET water bottles, but the far greater benefits of avoiding them in the first place.
- LCA of Waste Prevention Practices in Residential Construction. Understanding the relative environmental impacts and benefits of different waste prevention practices in residential construction is the purpose of this study. Oregon DEQ commissioned the research in part to identify high-impact actions and to help DEQ and others prioritize efforts related to materials management in buildings.
- Environmental Impacts from Carpet Discards Management Methods. This study estimates the greenhouse gas emissions (and several other environmental mpacts) of methods used to manage carpet discards generated by households and the construction & demolition industry: recycling, energy recovery (for fuel or waste-to-energy), and landfilling. The study indicates that recycling is the preferred end-of-life choice for carpet in terms of greenhouse gas emissions.
- LCA Benefits of Solid Waste Management. This summary estimates the greenhouse gas emission reductions associated with an increase of recycling and source reduction. The Minnesota Pollution Control Agency commissoned this study to evaluate two components of their 2006 strategic plan