## 4 Life-Cycle Assessment  
Interest in forest certification and eco-labeling began in the mid-1990's; corporations and individuals are becoming more environmentally aware and now ask questions on how particular products impact natural resources depletion or degrade the environment. Consumers want to know how products are manufactured, used, and recycled. There seems to be a slowly-developing market advantage for \"greener\" products produced by \"greener\" processes. The interest goes beyond the forest certification schemes. Thus it becomes critical for firms to develop means to determine environmental performance of their products and processes. It is not enough to meet minimum pollution and environmental standards; many consumers expect active improvement of environmental performance by the companies producing the goods they buy and they want to see this performance measured. Life cycle assessment (LCA) is one of these performance measures. LCA is an analysis method that measures the environmental impact of a product, service, process, or system over its total lifespan [26]. LCA is often a \"cradle-to-grave\" approach that includes the entire life span of the product or process. All stages or phases of the life span are evaluated as interdependent operations, meaning one operation will lead to the next operation. The methodology is well-defined in the literature and will only be briefly described here [27]. LCA is concerned with impacts on resources and the environment that occur at all stages of a product or process life: raw materials acquisition, manufacturing, transportation and distribution, use/reuse and maintenance, and recycling, waste management, and final disposal [28]. LCA is a method to assess the impact of products, services, systems, or processes on the environment by compiling an inventory of raw material and energy inputs and environmental releases, evaluating the environmental impact of those inputs and releases, and using the results in decision-making [29]. Environmental impacts center on resource use, human health, and ecological effects. These impacts may be direct or indirect. For example, the use of electricity for an energy source produces no direct greenhouse gas emissions; however, there are indirect greenhouse gas emissions from generating the electricity in the first place. LCA does not always use the full cradle-to-grave life span. Cradle-to-gate is common and runs from creation to the factory gate (where the product is ready for shipment to the consumer). Cradle-to-cradle is used when, instead of disposal, recycling efforts lead to a new identical product. Gate-to-gate is used at a single processing facility where it represents value-added in production (that is, time within just one factory). Finally, wheel-to-wheel is used to evaluate road transportation systems. LCA involves a systematic process that operates in phases with a focus on physical flows of energy and materials. The production chain or technological system is separated from the surrounding environment by a system boundary. Inputs to the system are raw materials and energy and outputs from the system are emissions and waste. First, is goal definition and scoping. The product, service, process, or system to be assessed must be defined, as well as the context in which the assessment will be made. System boundaries and the functional units (such as a ton of newsprint or 1,000 cups) of the system must be established and the environmental impacts under consideration must be identified [30]. Second, an inventory of energy, water, raw material usage, and environmental releases is established, plus the quantitative measures to evaluate them must be identified. These flows are connected to environmental impacts and involve raw materials, air emissions, soil and water, and final disposal [31]. This list of environmental impacts and outputs is called the Life Cycle Inventory (LCI).