How Do You Cool Your Data Center / Server Room?

Solar water heating tubes on the roof--that's an evacuated glass tube with a heat pipe running up hill to a heat exchanger embedded into a hot water loop.

Water-ammonia-hydrogen absorption refrigerator. The hot water loop loops down, runs into a water block that heats up the base reservoir of ammonia-water. This is in a small attic room with a weather sealed door and two fans (intake and exhaust). If the absorption refrigerator experiences a breach, the ammonia is vented to the atmosphere (it's poisonous, but harmless--ammonia is produced as part of the biological process, and is consumed by yeast and other microbes). Doesn't normally breach--the unit is sealed and needs zero maintenance ever.

The initial cooling loop ventilates heat into the room. After that, the cooled expanded ammonia travels through a condenser where it condenses into liquid ammonia at ridiculously low temperatures. The condenser itself is inside an oil-filled block which itself extends cooling fins into a run of duct work. The actual compartment with the condenser is separate, so if the condenser and housing crack it just splatters oil and evaporates ammonia into the outside atmosphere rather than into building duct work. Condensed ammonia goes back into the base unit where it's boiled again to recirculate.

The fans are run by compressed air. The air is compressed by sterling engine. Operating temperature is lower than the breakdown temperature of teflon seals, and so alpha sterling engine layout with hot teflon seals is used. No fluid lubrication required, so absolutely no maintenance. Compressed air also runs pumps that drive the hot loop and a cold loop that exchanges the sterling engine's heat with a ground tapped sink. A backup compressor is physically in another room and driven by electricity in case of failure of sterling engine. This is to avoid sparks in the event of a critical breach of the absorption refrigerator, instead allowing volatile hydrogen and ammonia to vent to atmosphere.

Hot loop is supplemented by a box of slate and oil to store excess heat collected during daylight hours for use at night. Hot loop is backed up by a separate, exchanger coupled loop that passes hot working fluid through a hot water exchanger coupled to a boiler to provide heat from gas via the building's existing hot water system. In the winter, system is bled during the day to provide building heat, and waste heat from heating turbine is used at night to supplement system if working temperature drops critically from lack of stored heat energy.

Impressed?

I have no idea how our servers are cooled - they're in "the cloud", so they could be cooling it with the souls of the damned for all I know.

Here in England it's summertime. We reached a high of 14C yesterday in my particular part of the country. That was on a day when some places received the average July rainfall for the whole month, in a single day. If we need to cool our computers all we need to do here is to open a window.

Summer in England: the rain gets warmer.

I remember when the Harrier was in flight test, there was a 19" rack mount mini-computer in a Nissen hut (corrugated iron) which needed a drastic environmental control soliution. A copper pipe was threaded through the cabinet with a funnel at the top and a thermos flask at the bottom. When it was hot, we poured liquid nitrogen through the pipe, but when it was cold we used hot water. Great skill was needed to keep within the safe working temperature range. Of course this was before health and safety made such solutions illegal.