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TABLE 1: Uptime Institute definitions of tier levels
ÌýTier ITier IITier IIITierIV
Number of delivery pathsOnly 1Only 11 Active, 1 Passive2 Active
RedundancyNN+1N+1S+S or 2(N+1)
CompartmentalisationNoNoNoYes
Concurrently maintainableNoNoYesYes
Fault tolerance to worst eventNoneNoneNoneYes
TABLE 2: The tier attributes of the sites from which the actual availability numbers were drawn
ÌýTier ITier IITier IITier IV
ºÚ¶´ÉçÇø typeTenantTenantStand-aloneStand-alone
StaffingNone1 Shift1 + Shifts%2224 by Forever%22
Useable for critical load100% N100% N90% N90% N
initial gross watts per square foot (W/ft²) (typical)20-3040-5040-6050-80
Ultimate gross W/ft² (typical)20-3040-50100-150 ¹ ² ³150+ ¹ ²
Uninterruptible coolingNoneNoneMaybeYes
Support space to raised-floor ratio20%30%80-90%²100+%
Raised-floor height (typical)12%2218%2230-35%22²30-36%22²
Floor loading ibs/ft² (typical)85100150150
Utility voltage (typical)208,480208, 48012-15 kV²12-15 kV²
Single points-of failureMany + human errorMany + human errorsSome + human errorNone + human error
Annual site-caused IT downtime (actuals)28.8 hours22.0 hours1.6 hours0.4 hours
Site availablity99.671%99.749%99.982%100.00%
Months to implement33-615-2015-20
Year first deployed1965197019851995
Construction cost (:30%)¹²³ÌýÌýÌýÌý
Raised floor$220/´Ú³Ù²$220/´Ú³Ù²$220/´Ú³Ù²$220/´Ú³Ù²
Useable UPS output$10,000/kW$11,000/kW$20,000/kW$22,000/kW
³ 100 W/ft² maximum for air-cooling over large areas, water or alternate cooling methods greater than 100 W/ft² (added costs excluded).
² Greater W/ft² densities require greater support space (100% at 100 W/ft² and up to 2 or more times at greater densities), higher raised floor, and if required over large areas, medium voltage service entrance.
¹ Excludes large architectural, engineering, and commissioning fees; permits and other fees; interest; and abnormal civil costs. These can be several million dollars. Assumes minimum of 15,000 ft² of raised floor. Architecturally plain one-story building, with power backbone sized to achieve ultimate capacity with installation of additional components or systems. Make adjustments for NYC, Chicago, and other high cost areas.
TABLE 3: Comparison of Various UPS Systems
Specification6 Pulse Series Online12 Pulse Series OnlineParallel OnlineHybrid RotaryDiesel Rotary UPS
Typical Operating Efficiency94%94%96%90 - 95%90 - 96%
Input Power Factor0.80.850.990.980.99
Output Voltage RegulationYesYesYesYesYes
Input Power Factor CorrectionNoNoYesYesYes
Energy StoreBatteryBattery or DC FlywheelBatteryBattery or DC FlywheelAC Flywheel
Output Fault Current Without Mains AvailableUp to 2.2Ìýx InUp to 2.2Ìý x InUp to 2.2Ìýx In14 x In10 - 12 x In
Range of sizes to Largest Unit Size0 – 800ÌýkVA0 – 800ÌýkVA500 kVA180 -1100ÌýkVA2 MVA
Actual useful size allowing for derating for leading Power Factor640 KVA640 KVA400 KVA1100ÌýKVA2 MVA
Indicative cost of UPS Only (£/kVA)£180 - £200£180 - £200£180 - £200£245 - £265N/A
Indicative Cost of UPS if derated to allow for leading power factors (£/kVA)£225 -£250£225 -£250£225 -£250£245 - £265N/A
Indicative cost of UPS in £/kVA on N+1 basis at most optimum module sizeTBCTBCTBCTBCTBC
Indicative cost of UPS and Standby Generation (£/kVA)£405 -£435£405 -£435£405 -£435£440 - £470£450 -£480
Indicative cost of UPS and Standby Generation if UPS derated to allow for leading power factors (£/kva)£450 -£485£450 -£485£450 - £485£440 - £470£450 -£480
Indicative Space Requirement of UPS and standby generation (m²/kVA)0.06 -0.070.06 -0.070.06 -0.070.06 - 0.070.04 -0.05