Operations Cost Example

We compare a conventional legacy data center with one populated with liquid cooled servers using direct touch technology. Even though some studies indicate that the cooling overhead could be as little as 5% of IT load for the direct touch system, we have assumed the more pessimistic number of 15%. Even so, a net energy saving of 36% is achieved. While this represents a substantial $1.1M in energy cost reduction, it also offers the data center owner the opportunity to add 2,800 more servers with the same amount of power as servers can be packed much more densely.

	Air Cooled 1U Sun servers	Liquid Cooled Sun 1U servers
IT power (W)	300	300
Fans (W)	50	0
Power supply efficiency	89%	89%
Total server power (W)	393	337
Cooling Overhead	55%	15%
Distribution overhead	3%	3%
Total power/server (W)	628	399
5000 Servers (KW/yr)	3139	1996
Energy Cost per KWh	$0.11	$0.11
Annual power cost	$   3,024,919	$   1,923,681
Saving		36%
Power density (W/sq-ft)	100	809
Required Area (sq-ft)	19663	2083
Lease rate/year/sq-ft	$       60	$       60
Lease cost	$   1,179,775	$    125,000
Electrical plant depn & maint	$   3,024,919	$   1,923,681
Cooling plant depn & maint	$      536,679	$     125,457
Annual power cost	$    3,024,919	$    1,923,681
Opex	$    7,766,293	$    4,097,820
Saving		47%

The table is derived from actual measurements made on Sun servers with and without fans. The Opex computation is derived from Chakandra Patel's (HP Labs HPL-2005-107R1) model.