RE: DATACENTER: Cooling and Cost Data for Web Hosting Data Centers

["Julian, Dennis R." <DJulian@vanzelm.com>]

"Revised"
Some Rule of Thumb formulas to assist in designing Data Centers:

Watts per square foot is application specific.  For instance for stacked
Compaq Himalaya servers the W/SF could be 121 W/SF and EMC Symmetric 5700
storage devices could be 196.3 W/SF (including their service area).  Since a
Data Center is not normally comprised of only these devices we need to
develop an average per SF load.  30 W/SF is probably a minimum design load
but the definition of SF needs to be carefully considered, typically it
includes all raised floor areas including those not specifically used for
equipment.

RS Means at www.rsmeans.com has some pricing info for "telephone exchanges"
which are similar in redundancy requirements but probably has less power
density (therefore less expensive).  It does allow you to estimate a range
of costs corrected for the area of the country you are in.  But costs are
dramatically effected by the amount of redundancy/reliability required.

Typical cabinet/rack space with electronic equipment with its associated
front and back access space requires approximately 20 SF per cabinet/rack.
This is acceptable for estimating space for the racks only. To account for
redundant power distribution and cooling units use 35 SF per cabinet to
estimate the size of an entire Data Center computer room. These numbers do
not account for auxiliary uses of the space such as staging, cabling racks,
control/monitoring stations etc.

The size of the uninterruptible power supply (UPS) can be estimated as
follows:

UPS = (Equipment load + Growth) X 1.1 safety factor. Round up to standard
size.

Air conditioning (AC) is approximately equal to the UPS size.

Generator = UPS/(0.91 efficiency) x 1.15(battery charging) + AC load

All numbers are in kW.  These sizes are for system capacities and do not
include redundant units required for reliability.

For estimating purposes kW can be used.  For accuracy kVA should be used.
For single phase electronics

		kVA = Volts times amps = kW/(power factor)

		power factor varies but could be estimated at 0.8.

UPS's and generators are rated in three phase kW and kVA.

		3 phase kVA = (single phase kVA) / 3

12,000 BTU's = 1 ton of air conditioning

1 watt = 3.412 BTU

Hope this is useful.

Dennis R. Julian, P.E., RCDD

Technical Associate
Critical Facilities Engineering Team

van Zelm Heywood & Shadford Inc
Mechanical and Electrical Engineers
29 South Main Street West Hartford, CT 06107-2420
Phone (860) 521-4329 x373    Fax (860) 521-5620
djulian@vanzelm.com
www.vanzelm.com


-----Original Message-----
From: W Halls [mailto:wssdc@yahoo.com]
Sent: Wednesday, December 08, 1999 6:06 PM
To: datacenter@shorty.com
Subject: DATACENTER: Cooling and Cost Data for Web Hosting Data Centers



To what specs are people designing web hosting data
center cooling for ? 30/60/90W/sq foot ?

Also, is there a pointer to some benchmark data for
the construction costs for these data centers ? I have
seen estimates from 300$/sq foot all the way to
$1000/sq foot with the variation based mostly on power
and cooling

What net square foot of raised floor to overall gross
square foot ratios are people seeing ? i.e how many
cabinets or racks per square foot ?

Thanks
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