Early Data Center Planning – Rules of Thumb
Critical Load, Essential Load, & Non-Essential Load
By: Dan Fanning, LEED AP, DC CEP, HCC, Projects & Engineering Manager
Critical Load – a load that cannot be interrupted.
- 24/7 Critical Data Equipment
- Service Providers
- Emergency Call Services
Essential Load – a load that can be interrupted but can be restored by a generator.
- The Mechanical Units
- Motors and Pumps
- Refrigeration Units
- Lighting
Non-Essential Load – a load that does not affect the Critical Data Center operations.
- Work Stations
- Non-Essential equipment
- General Area Mechanical
Formulas – divide the building load into the above three categories. Convert to watts and apply the following formulas:
-
(The Critical Load + Projected Growth) * 25% = UPS kW
-
(The Critical Load + Essential Load + (20% of the UPS size)) * 25% = X
X * 3.414 = BTU/h
BTU/h/12000= Tons (12000 is a factor based on an ambient outside air temperature of 95 degrees F)
-
UPS * 1.65 = Load A
Essential Load + (Tons * 3.54 kW) = Load B -
- (Load A + Load B) + Projected Growth = Generator Size
NOTE: These are basic rules of thumb and do not account for altitude, skin load, outside air temperature, raised floor height, or other site-specific factors.