Ladybug for Grasshopper
Ladybug is a free and open source environmental plugin for Grasshopper to help designers create an environmentally-conscious architectural design. The initial step in the design process should be the weather data analysis; a thorough understanding of the weather data will, more likely, lead designers to high-performance design decisions.
Ladybug imports standard EnergyPlus Weather files (.EPW) in Grasshopper and provides a variety of 2D and 3D designer-friendly interactive graphics to support the decision-making process during the initial stages of design. The tool also provides further support for designers to test their initial design options for implications from radiation and sunlight-hours analyses results. Integration with Grasshopper allows for an almost instantaneous feedback on design modifications, and as it runs within the design environment, the information and analysis is interactive.
Here is Ladybug in a less than 5-minute video
Licence
Ladybug: A Plugin for Environmental Analysis (GPL) started by Mostapha Sadeghipour Roudsari
Copyright (c) 2013-2015, Mostapha Sadeghipour Roudsari
Ladybug is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
Ladybug is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Ladybug; If not, see http://www.gnu.org/licenses/.
@license GPL-3.0+ http://spdx.org/licenses/GPL-3.0+
Useful links
Ladybug group page on Grasshopper