So Will Prefab Cost Me More or Not?

Prefabricated modular data centres can offer real benefits. These include speed of deployment, greater reliability, greater flexibility to scale, and improved predictability.  

But when it comes to cost, there’s usually a lot of discussion about whether it’ll save you money or cost you a premium over traditional, stick-built sites.

Our Whitepaper, Quantitative Analysis of a Prefabricated vs. Traditional Data Centre, is our attempt to set the record straight. 

In this paper, we analyse the capital costs of two data centres whose capacity, cooling architecture, power architecture, level of redundancy, density and number of racks are the same.  

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By keeping everything the same, we were able to isolate the cost differences of the design approach (prefab vs. stick-built). 

We used one of our reference designs – a 440 kW tier 3 data centre, as the basis for the design attributes.

Romonet data center modeling software was used to complete the analysis and Romonet experts reviewed and validated our analysis model.

How does the choice stack up?

When we looked at all capital costs for the physical infrastructure of this particular design (including material, design, site prep, installation, commissioning), the prefabricated approach was 2% less than the stick-built

Given the margin of error in this type of cost exercise, this led us to the conclusion that the two approaches cost roughly the same.

The materials for prefab come at a capex premium over traditional systems. This shouldn’t come as a surprise, given prefab modules are shipped with the physical infrastructure preassembled, so they include the physical housing (the containers), as well as the cost of labour for the factory integration.

Field labour and space costs, however, favour prefab designs, which is why the two approaches end up equal in the end. The amount of onsite labor (both electrical and mechanical) is reduced since integration work done in the factory results in less field work.

Space cost (cost of the land, building, site prep work) represented the biggest savings opportunity in this analysis.

We chose a “typical” building cost in our analysis, but actual costs vary significantly from country to country, and site to site. 

Compare costs for a data centre with different attributes using our handy TradeOff Tool 

In general, prefabricated designs become more cost effective when compared to a traditional data centre within a more expensive building or space. Likewise, the traditional approach becomes more economical if there is a low cost space available.

Another key factor was power density per rack. As density decreases, the number of racks and rack PDUs increases, but more importantly the size of the building and/or containers also increases.

Having more or larger containers would represent additional overhead which diminishes the savings, and may even swing the results in favour of traditional as densities continue to drop.

[Whitepaper] Drivers & benefits of Edge Computing

The bottom line: prefab versus stick built?

A direct comparison of capital cost alone generally doesn’t provide a strong case to shift to a prefabricated design approach.

It’s important to understand your other business drivers in making this important decision, such as the value to deploy faster, simplicity in repeating solutions in multiple locations, or the predictability in project cost and timelines. 

These are more difficult items to quantify and compare, but are common reasons why actual owners and operators have opted for a prefabricated modular approach. 

Prefabricated data centres offer a different way to deploy infrastructure which can offer great benefits depending on the application and specific site challenges. As manufacturers continue to optimise and standardise prefabricated module designs, it s likely that the enclosure and implementation costs will continue to decrease.

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