The Ladybug Tools (LBT) Plugin for Grasshopper includes a wide range of building simulation capabilities that support environmental design. It is composed of a few hundred Grasshopper components, which are organized into different insects, each of which is specialized in a particular set of capabilities.
Ladybug - Weather data analysis and visualization.
Honeybee - Detailed modeling of buildings in various simulation engines.
HB-Radiance - Radiance simulation (daylight, radiation, glare/visual comfort).
HB-Energy - E+/OpenStudio simulation (energy use, HVAC sizing, thermal comfort).
Dragonfly - Abstracted modeling of large buildings and districts in various simulation engines.
See the lbt-grasshopper wiki for instructions on how to install the Grasshopper plugin for free.
Ladybug Tools also offers purchase-able single-click executable installers, which make it much faster and easier to install, particularly in the case of deploying to multiple machines. If you are interested in purchasing the installer, please email email@example.com.
All regularly-updated sample files for the LBT Grasshopper plugin are included in the .zip file that comes with the Food4Rhino installer.