This document discusses computational design in architecture and building simulation software. It covers the need for environmental building simulation tools, how to select and evaluate such tools, and what the future of building system modeling may look like. Key points include that simulation tools can evaluate energy efficiency, renewable energy, and sustainability in buildings. Selection criteria include the tool's capabilities, ease of use, cost, and support. The document also outlines the steps to develop a simulation model and experiment and stresses the importance of validating models against real data.