The International Organization of Standardization (ISO) wrote guidelines for life cycle assessment. Examining manufacturing and construction processes and making comparisons between material and process options has great promise for encouraging positive environmental impacts. Standardization of this process leads to greater opportunity for data sharing and adds consistency to reports from different people and organizations. The two reference standards used are ISO 14040-2006 and ISO 14044-2006. These standards describe the principals and requirements for writing an LCA. It is important to note that creating an LCA is an iterative process, and the scope may change throughout the data collection phase in order to make sure the original goal is met.