Cooling

KTH has a local district cooling system with pipes carrying cold water all over the campus. The cold water is produced locally with outdoor coolers, or as a by-product of producing heat (to warm up the facilities in the winter) with a large heat pump. The cold water enters the basement of the PDC building and goes to several heat exchangers. One reason is to form smaller closed loops of piping in the building with water that is of the appropriate temperatures for the different cooling methods that we use. PDC uses three different types of cooling (which are representative of different generations of cooling solutions):

1. Computer Room Air Conditioners (CRAC) which cool the entire computer room,
2. encapsulated cooling where all the heat from the computers is encapsulated in an enclosure and then cooled, and
3. water cooling where water of a somewhat higher temperature cools the computer directly (and almost no heat is emitted to the room).

As the district cooling is not 100 % reliable, we also need backup cooling and we use different backup methods for each of the three alternatives above but all are based on ordinary tap water with or without compressors.