As PCs became faster and more powerful, projecting energy consumption and cost using whole-building computer models has expanded. New building codes now allow use of such models to demonstrate the energy efficiency compliance of proposed building designs. Certification for LEED™ credits (www.leed-building.org), which may yield tax breaks and other benefits, also allows use of computer models to secure certification. Such models are also routinely used to quantify energy efficiency options under consideration in new or existing buildings. Once created, a computer model may be quite cost effective because only very small changes are needed to simulate each measure.
But what exactly is a computer model, and why is it any better than standard methods for calculating whole-building energy usage?