The embedded calendar below hosts both the HEEN calendar and many calendar's of clubs from across campus. You should be able to find most student-run energy and environment events here including HEEN-sponsored events such as the "Stimulating Energy" conference held at Harvard in May 2009 under the auspices of the Energy Network. For any other energy or environment related event we refer you to the very complete calendar of the Harvard University Center for the Environment, which can be found here.
For the Harvard Office of Sustainability calendar please go here