Graphs are an effective way of displaying quantitative and statistical information. Unfortunately, only a few studies have systematically looked at presenting building energy data in forms which are both informative, visually efficient, and easy to comprehend. Recent advancements in computing including the development of sophisticated graphing packages and powerful desktop computers have made the concept of graphical displays or graphical indices more timely than ever before. In this two part paper, graphical displays or indices are reviewed and discussed that can be used to analyze several years of hourly data (20,000 to 30,000 data points). The purpose of these papers is to show how graphical indices can be used to help a building energy analyst view large amounts of hourly building energy consumption data in order to quickly and efficiently analyze the data, check for errors, or establish time and temperature related trends over a large period of time. Data from case study buildings in Texas(1) are used to demonstrate the indices. Part I reviews the literature on graphical presentations of building energy use data and graphical perception and presents two graphical indices. Part II provides four additional graphical indices in use in the data review process for the Texas LoanSTAR program.(2)