The concept of an interactive envelope materials database for whole-building energy simulation programs is presented in this paper. This database was developed to reinforce an accurate, fast, and simple energy analysis of building energy consumption in shell-dominated buildings. The main purpose of this database is to serve architects, system designers, and energy modelers by enabling detailed envelope analysis during whole-building energy simulations. However, it can also be utilized for performance comparisons between different envelope technologies. The user simply selects the material configuration and sets dimensions. Later, the Internet program calculates whole wall/roof or floor R-values, generates three-dimensional dynamic thermal characteristics, and calculates detailed air leakage for the selected building envelope system. This information is then converted into the format required by programs such as BLAST, DOE-2, or ENERGY PLUS.