The historic method of specifying data center power density using a single number of watts per square foot (or watts per square meter) is an unfortunate practice that has caused needless confusion as well as waste of energy and money. There are four major problems with the historic practice of describing power density in terms of watts per square foot or watts per square meter.
First, what is included in the area calculation or how it relates to the number of IT racks/devices is not defined. Secondly, what is included in the power calculation is not defined. There’s no information about the variation in power. And, lastly, it is not clear how this number is used in a facility with a changing growth plan or that is built out over time.
Vague specs like this lead to problems. Specify too low a density and performance becomes unpredictable with various overload and overheating problems occurring; specify too high a power density and first cost and operating expenses are needlessly increased.
More accurately specify power density
A different approach is needed. In the White Paper, “Calculating Space and Power Density Requirements for Data Centers,” a proven method with four main features can help ensure a more accurate power density measurement. This method comprehends that:
- 1. The IT cabinet is the unit of physical space in the density specification, instead of the floor area.
- 2. Hierarchical and modular specification enables different rooms and zones to have varied density requirements.
- 3. IT cabinets in data centers have different power requirements which may not be well-defined in advance.
- 4. IT equipment cabinets may have power requirements that change over time.