Going modular – skid vs volumetric?
By Brandon Gries, Cupertino Electric
Like a classic Bell curve, modern construction approaches can range from pure volumetric modular on one end and pure traditional construction on the other
In these uncertain times, nothing is guaranteed. However, one thing that has been predictable over the last few years has been a shortage of skilled labor for construction projects. This is especially the case in parts of the US where large data center construction is booming.
For many data center owners, the shortage of skilled labor in prime locations has driven a shift toward the use of modular construction techniques. By moving much or all of the construction and labor associated with data center builds offsite to fully staffed manufacturing facilities, owners can reduce their labor risk and reap other rewards.
Once modular construction enters the conversation, the rationale for this approach becomes compelling. Modular construction doesn’t just reduce labor risk, it also enables the compression of construction timeframes, increases quality at source, enables improved quality controls and product testing, and decreases weather-related delays that plague construction projects in many parts of the country for large portions of the year.
The challenge for businesses choosing to use a modular approach is knowing how to use it appropriately to maximize the positive impacts and minimize the potential pitfalls. The primary decision centers around which approach makes the most sense for the project at hand: volumetric or skid-based modular construction.
It is very tempting, once a customer has committed to utilizing modular construction, to want to modularize everything. This includes all elements of the shell of the building, in addition to all of the utilities and functions inside. This is a volumetric modular approach. For some projects, this may well be the best approach. But for others, this all-in modular approach can introduce its own set of issues and constraints that make it less than ideal. In those instances, a skid-based approach – where elements inside the building best suited for modularization are identified, built offsite into large modules called skids, then shipped and installed on a site where a shell has already been constructed – is best.
How to determine which approach is best is critical to the ultimate success of a modular project. Our experience building modular options suggests three elements that businesses should consider when simplifying their decision:
1 Does your project REQUIRE a volumetric approach?
This is quite different from asking whether you COULD use this approach. It may be surprising to hear that some aspects of volumetric modular construction are significantly less efficient than their traditional alternatives. This isn’t a result of bad planning or design by modular builders but is the result of specific design imperatives. The volumetric approach requires that each building module is fully framed to safely support itself. While there are good reasons for this, it means the volumetric approach inherently requires different mix of materials, which can be less efficient. Pulling in the opposite direction is the extreme efficiency of certain processes already built into traditional construction. Structural steel is a great example. A traditional beam and column structure has been designed to minimize the amount of steel needed to build the total volume. This means you will spend more on structural steel in a volumetric solution than in a beam and column structure.
So, the question becomes whether the benefits to your project of using a volumetric approach outweigh the inefficiencies that come with it. If for example your project requires the smallest solution possible, volumetric may be the way to go. Alternatively, if the goal is to reduce the number of inefficient/expensive components in the project to a minimum, a hybrid approach utilizing skids and a traditionally built shell may be a better option.
2 How important is operational efficiency to you?
Have you ever wondered why your super-thin laptop is significantly less powerful than its desktop equivalent, despite being more expensive? One reason is space. Computing systems produce a lot of heat, and efficiently removing that heat requires a lot of air. The same principle applies to data centers. When building a volumetric system, you must factor in rules and regulations around what size of item can be transported. These constraints lead to building smaller, tighter spaces which may lead to much less efficient mechanical systems.
Similar parallels arise when it comes to maintenance. Like big computers, large data centers are easier to access and repair. Smaller spaces can mean more challenges for upkeep and repair than spaces with greater volume and larger maintenance clearances. It’s all about trade-offs. If your project has constraints that require tighter spacing, a volumetric approach may be ideal. If you can afford the extra air, a skid-based approach can provide real operational benefits. When choosing the right modular approach, it’s essential to identify the optimal balance between your project’s space efficiency and operational efficiency.
3 How big and widespread is your program?
Everyone involved in construction understands that permitting is a necessary element of any project. If you are building a single data center, then the permitting process will look similar, whether you use a traditional or modular manner. However, if you have a larger program and want to move toward modular, permitting is a real issue. If you want to use standardized volumetric modular building components, you will need to identify all the jurisdictions where you plan to build and ensure that your designs pass inspection in all of them. This may add cost and complexity to the design. In addition, you will likely need to get permits before construction can start and schedule inspections at key milestone activities.
If the number of installation locations is small or predictable in advance, these considerations may not be an issue. However, if you want the flexibility to build multiple identical components and redirect one originally identified for an Oregon location to Texas because that project has jumped ahead in schedule, then a skid-based approach might be best. A skid-based modular approach can provide more flexibility, reduce permitting headaches, and deliver greater ability to build ahead to meet capacity. Understanding the scale and scope of your project is key to identifying the approach that best for you.
The best approach
By now it is probably clear that while using a modular approach to building provides an elegant solution to address some constraints of traditional construction, there are different flavors of modular data center construction. Like a classic Bell curve, modern construction approaches can range from pure volumetric modular on one end and pure traditional construction on the other. In the middle of the Bell curve, the modular approach that we’ve seen work most often is one that uses a mix of the best, most efficient traditional construction aspects combined with targeted, skid-based modular. This hybrid zone contains the sweet spot for most projects, but where your project sits, and how to arrive at the right mix depends on a range of factors. The key to success is to understand the pros and cons of each approach, and the trade-offs inherent in each.
Find the best combination for your data center project and modular can help make it a success.
Source: Data Centre Dynamics