This Helsinki Cathedral Cools Servers and Heats Homes

In Helsinki, Finland, water from the Baltic Sea cools a database server center in the former bomb shelter in this cathedral. Then, the hot water is used to heat 500 houses. This system has been functioning for a few weeks and has already reduced demand on coal-fired power stations. It's expected to save about $215,000 per year. It's brilliantly efficient. Necessity and high Finnish electricity prices are the mother of invention.

Photo by Will Etling.