After doing some detective work in Google, I found out more information about the facility where MyGreenHosting keeps their servers.

The Thor Data Center (THORDC) is located in Hafnarfjordur, just south of Reykjavik in Iceland. The facility is powered by renewable hydropower and geothermal energy. It uses modular natural free cooling, a technology that takes advantage of the naturally cool outside air of the Icelandic climate to maintain the correct operating temperature and humidity level inside the data storage containers. Effectively this hosting environment is 100% green with a zero carbon footprint.

Here is an 8 minute video in YouTube made by AST Modular showing a tour around the data center and describing its technologies. I encourage you to watch it.