Cooling Capacity Factor
The Best Measurement of Data Center Cooling Efficiency Since PUE.
What is the Cooling Capacity Factor?
The Cooling Capacity Factor (CCF) is the ratio of total installed nameplate cooling capacity to the critical load. This ratio should be about 1.2x or 120%. If the CCF is greater than 1.2 then it is very likely there are opportunities for right-sizing cooling capacity. In turn, this will improve energy efficiency, reduce operating expenses, improve the room’s environment, and support increasing server density.
While this analysis is not intended to replace an in-depth onsite assessment, this calculator’s estimated CCF is an important step towards understanding the utilization of existing cooling capacity.
If the CCF for a room is between 1.0 and 1.1, then there is little to no redundant cooling capacity. Airflow management (AFM) improvements will likely improve IT equipment intake temperatures, and create an environment where cooling unit set points can be raised which increases cooling unit efficiency. But there is no opportunity to turn off cooling units.
If a CCF is 1.1 to 1.2 then the number of running cooling units is likely being managed well. There are approximately 1 to 2 redundant cooling units for each 10 units running. In most cases, this is sufficient to maintain the room temperatures when a cooling unit fails. It is not recommended that any cooling units be turned off unless the room has 24-hour-by-forever monitoring and staffing.
For rooms with a CCF of 1.2 to 1.5, there is moderate opportunity to realize savings from turning off cooling units. This can often only be done once AFM has been effectively implemented. This does not require full containment strategies but does require thorough sealing of raised floor penetrations and open spaces in racks, and best practice placement of perforated tiles and grills.
A CCF of 1.5 to 3.0 is most common. These rooms have substantial opportunity to reduce operating cost, improve the IT environment, and increase the IT load that can be effectively cooled. Rooms in this range often have significant stranded cooling capacity that can be freed up by improving AFM.
Rooms with a CCF greater than 3.0 have great potential for improvement. A CCF of 3.0 means that the total rated cooling capacity of running units 3 times 110% of the IT load.
While not required for calculating a room’s CCF, a couple other metrics are also fundamental for determining the effectiveness and efficiency of the AFM in a computer room. The number of hot and cold spots, and the delta temperature from cooling unit supply to IT equipment intake and from IT equipment exhaust to cooling unit return, clearly reveal the amount of mixing that occurs in the room.
To find your CCF using our free calculator, you’ll need to enter the following information:
- Computer room area (SqFt)
- Rated Capacity of your cooling unit (If you know your cooling units rated capacity in kilo watts (kW) then divide kW by 3.516 to determine capacity in tons)
- Number of cooling units installed in each room
- Number of cooling units running in each room
- Fan Motor Horsepower
- Cooling unit fan motors are running at full speed, no variable frequency drives (VFD)
- Cooling units are capable of delivering their full rated capacity
- Heat load other than IT load (building envelope, lights, people, etc.) is 10% or less of IT load