LCI/LCA:  Life Cycle Inventories and Assessment

Bruce Lippke
College of Forest Resources, University of Washington, and
President CORRIM, the Consortium for Research on Renewable Industrial Materials
 

Environmental performance issues have been important to the forest and paper industry for decades. The effort to clean up point source pollution in the 70’s resulted in substantial changes in the production processes for pulp and paper mills.  In the 90’s the sustainability of wood production and habitat protection was a central focus resulting in 3^rd party certification for sustainable forest management.  The turn of the century has produced record energy prices, increased concerns about global warming caused by greenhouse gas emissions, and an increased emphasis on use of renewable resources.  Because of the increasing focus on environmental issues, new tools have arisen to analyze the sources and impacts of environmental burdens. 
 

Environmental Life Cycle Inventory and Life Cycle Assessment (LCI/LCA) has become an important tool for both policy makers and the private sector to identify the source of environmental burdens and methods to reduce them.  Sometime referred to as a “cradle to grave’ analysis the objective of an LCI is to measure every input: all raw materials (including energy); and every output: products, co-products, and emissions to air, water, and land.  When the input is a processed good it requires tracing inputs back to their initial stages of processing (the cradle) such as the mining extraction of iron or fossil fuel or the regeneration of a renewable resource such as wood fiber. 
 

These inputs and outputs are referred to as the Life Cycle Inventory of all environmental performance measures, a complete footprint of environmental burdens associated with a standard unit of product output like the burden of CO2 emissions per board foot of lumber produced.  For a more complex unit of output like a residential structure, all of the LCI’s for each product making up the bill of materials and all the transportation and construction steps to complete the structure are accumulated.  To complete the cycle of analysis from “cradle to grave” the flow becomes even more complex with the addition of all the inputs and outputs associated with “using” the house for its expected life, including heating and cooling; the maintenance phase; and final demolition, including post consumer recycling, land fill wastes and their ultimate decomposition. 
 

While this process represents an enormous data collection requirement, the benefits are clear.  The LCI provides a very complete quantitative measure of environmental burdens that can be used to identify their sources and opportunities for investing in improvements in product selection, design or process changes. 
 

Since an LCI is composed of hundreds of emissions and inputs, the assessment task is made easier by grouping emissions into just a few categories with indices that measures the risk to human health or the ecosystem.  Typical categories based on outputs are green house gases contributing to Global Warming Potential measured in equivalent units of CO2 emissions; water pollution measured as the worst offending toxic substance in terms of EPA safe drinking standards; the worst offending air pollutant; solid waste to landfills; and energy or fossil energy which contributes to many emissions.  Categories based on inputs include the use rate or rate of exhausting known reserves for non-renewable resources. Categories for impacts on the land include acres used as an input or disturbed ecosystems as an output burden.
 

Studies have shown that products and structures using wood, a renewable resource, generally result in lighter environmental burdens than other alternatives like steel and concrete products (Lippke et al 2004). Processing wood relies heavily on the use of biofuels which reduces fossil fuel consumption producing lower burdens to global warming potential, air and water pollution, whereas steel and concrete are fossil energy intensive producing much larger emissions. LCI/LCA methods are rigorous although flexible enough to adapt the method to many product alternatives or end uses of interest.  The International Organization for Standards has produced a series of standards and examples to guide practitioners (ISO 14040, 14042-43, 14047). 
 

A conceptual weakness can be the difficulty in analyzing long-lived stages of processing.  LCIs are traditionally developed as a current cross sectional profile of every stage of process that is required.  That alleviates the difficulty of measuring forest regeneration 50 years ago or the demolition of a house 100 years in the future as both stages are measured by current activities. However it does not eliminate the importance of the time value of money.  While the heating and cooling of a house over a 100 year life will likely be many times larger than the energy in constructing a house, an investment in saving energy 100 years in the future is not as valuable as one that can save that energy today.  Discounting methods for equating the value of investments that produce different values over time, as generally used for investment analysis, still apply to Life Cycle Analysis.  The most cost effective investment will seek to get the largest environmental benefit after discounting its value and related costs to the present time using the interest rate as the time value of benefits and costs. 
 

LCI/LCA is expected to grow in importance and use with the development of publicly available and professionally reviewed databases, which is the objective of government agencies.  It may also become the primary criteria for environmental purchasing standards and product labeling in order to help guide-purchasing decisions that will lower environmental burdens. Developing environmental performance criteria is difficult and can easily be biased unless the criteria are scientifically based such as LCI/LCA.
 

References

 
ISO 14040, 14042-43, 14047, 1998-2003. Life cycle assessment standards. International Organization for Standardization. Geneva, Switzerland.
 
Lippke, B., J. Wilson, J. Perez-Garcia, J. Bowyer, J. Meil.  2004.  The Consortium for Research on Renewable Industrial Materials: Life-Cycle Environmental Performance of Renewable Building Materials. Forest Products Journal. June 2004, Vol. 54, No. 6.
 
 
 Updated: 21 April 2007