The latest in our TradeOff Tool collection is the Prefabricated vs. Traditional Data Center Cost Calculator, which can be an important tool during the planning phase of a data center project when the topic of prefabricated (containerized) data centers has been raised. This tool can help illustrate under what conditions it may make sense to go with a prefab approach, and under what conditions it doesn’t. Factors such as the starting and ending load, power density, space costs, and where modules would be placed (indoors vs. outdoors, for example), all influence the answer.
As with my other TradeOff Tool blogs, I wanted to share some background on the tool, in terms of its methodology, assumptions, and data sources, so that you can feel confident in using the tool as an input to your planning decision.
This tool uses the same fundamental methodology as our Data Center Capital Cost Calculator, which I described in my past blog. It is a rough order of magnitude estimator (+/- 20%), so not a quoting tool. We used a mix of Schneider pricing, 3rd party pricing, and partner and customer quotes to derive the subsystem costs, the density cost multipliers, the capacity multiplier, and the redundancy multipliers. The reason for the multipliers is so that the tool can estimate a wide range of configurations, from small to large data centers, low to high density racks, different architectures, etc.
The way the tool is structured, you can choose to compare a completely prefabricated data center (meaning power, cooling, and IT are all prefabricated modules) to a traditional build, or you can choose parts of the data center to be prefabricated (i.e. just power, just cooling, just IT, or a combination).
The key cost drivers that determine the approach that makes the most financial sense are:
- Cooling architecture – The tool allows you to select a traditional water-cooled chiller plant, a packaged chiller plant with prefabricated hydronics, or an indirect air economizer.
- Rack density – The tool lets you vary the density from 1 to 20 kW/rack. This has a tremendous impact on the result, specifically with the IT module vs. a traditional IT space. The lower the density per rack, the more space you need for a given capacity.
- Placement of prefab modules – You can input whether modules will be placed indoors (in a warehouse or finished office-type space) or outdoors. The cost per sq m or per sq ft of the space varies quite a bit based on the type of space selected. Obviously, a finished space costs more than a warehouse space which costs more than an outdoor space. The tool lets you adjust these space costs to values that make sense for your location.
- Build vs. lease –If you build and own the land, the cost becomes a capex driver; if it is a lease scenario, those costs are now operating costs.
The calculator provides a summary of the capex of traditional vs. prefabricated and demonstrates the percent difference. There are also two bar charts in the results. The first is an overview of the equipment, design/install, and space/building costs for each approach, and the other is a drill-down into the power, cooling, and IT spaces.
Some key assumptions used in our mathematical model were:
- The load scales linearly from starting load to final load, in number of years input by user
- With a prefab build, 10% of infrastructure must be built up front for final load
- With a traditional build, 30% of infrastructure must be built up front for final load
- Space requirement is a function of density per rack
- Labor rate data comes from a US Dept of Labor, Bureau of Labor Statistics, January 2008 report, and currency conversions are based on data from http://oanda.com
Take a few minutes and try out the tool; it’s great for guiding discussions around whether to go with prefabricated data center modules, and it’ll help justify the decision you make to management. Remember, the full set of our Schneider Electric TradeOff Tools can be found at http://tools.apc.com. As always, feedback on our tools is encouraged!