Shape coefficient is a key factor to evaluate building energy efficiency. But few investigations have been done on calculating shape coefficient for existing building using Google Earth. Based on Google Earth, GIS slope analysis, astronomy principle and geometry, a new calculation method for shape coefficient of residential building is presented in this paper. Conditions such as date of shooting RS image, slope angle, solar elevation angle and solar azimuth are discussed for its practical application. From a case study of residential buildings in Lin'an city, the new method is found to be more efficient than field measurement at the same precision level. Due to its great convenience in calculating building shape coefficient this new method is especially applicable to evaluate energy-saving potential of existing buildings in a certain area. (C) 2014 Elsevier B.V. All rights reserved.