ABSTRACT Existing buildings now represent the greatest opportunity to improve building energy performance. Building energy simulation is becoming increasingly important because the simulation results can assist the decision makers to quickly make the solution for improving building energy efficiency and reducing environmental impacts. However, most of the time there is no available as-is 3D building models for the existing buildings to conduct energy simulation. Nowadays, it is a common practice to obtain point clouds of existing buildings through using 3D laser scanning technologies for as-is building modeling. Current methods using point clouds need manual processes to prepare thermal zones based on point clouds data which is very time consuming and labor intensive. This paper introduces an automated thermal zone creation method to create both a building zone and room zones. A building thermal envelope was extracted from 3D point clouds. Then, 2D building floor plans were used as references to accurately determine the location and size of each thermal zone. A preliminary experiment has been conducted on a residential house to validate the proposed method, and the created building components and thermal zones were successfully imported into a building energy simulation program and ready for various energy analyses. INTRODUCTION Improving Energy efficiency has been a popular subject for the whole world since the energy crisis in the late 1970's (Maldague 2001). Buildings account for 16 percent of world energy consumption (EIA 2009), with a higher share in developed economies (nearly 42 percent of total energy use in the United States) (DOE 2010). Each year, roughly four percent of the building is newly constructed or renovated, thus the existing building stock will have the majority of opportunities to improve energy efficiency over the next several decades. Thus, existing buildings represent the greatest opportunity to improve building energy efficiency and reduce environmental impacts. The public and private building stocks are increasingly mandated to meet green standards by the federal government and jurisdictions across the country. The fact that people gradually consider saving energy and lowering greenhouse gas emissions as civil virtues boosts the private demand for green building
