Typical data centers need stout structural support to ensure that the heavy equipment inside will be able to be supported without any possible issues. Increased density of IT equipment doesn’t just mean the power and cooling needs, but the servers themselves are physically weighing more than before. For a data center structural design this simply means that either the floor slab has to be stronger or the load needs to be spread across more of the floor to keep it from sagging or causing point penetrations failures. With a single floor design a slab-on-grade is an easy solution. Multiple floors entails a bit more thought and analysis, as a second floor supporting 5,000 lbs. cabinets as well as the structural ceiling for the first floor that carries the conduits, cabling, and more requires robust structures that add to the construction costs and time, whether or not there is a raised floor. The UPS and batteries that are likely on the same floor weigh just as much as the cabinets and used to be the only equipment in the data center that caused structural designers to worry about weight. With any tall building, the need to resist lateral loads is greater, and with the heavier load of a data center this increases the supporting assembly even more. Add in that there are likely requirements to resist severe weather, such as tornados, or other threats and the structure is then engineered to be even stouter.
The increases of costs aren’t just due to the structural adjustments but also to the additional needs for the building to function, such as stairs and elevators. The construction of multi-level facilities generally takes longer and costs more depending on the height, with every additional story increasing the cost cumulatively. At a certain point the cost to increase has diminishing returns, which some have found to be at three stories. To design a generic data center up certainly makes sense when the cost of the land is greater than about $800,000 per acre; with land at less than this amount the costs to increase the building height start to weigh against the increased height.
Regardless of the cost as the determining factor, building higher has been done in a cost-effective manner by many of the larger data center owners. There are also numerous benefits that relate to functionality improvements, such as how power and cooling are fed through the building as well as easier egress through the facility. Cost efficiencies can include reduction of time for the site to be permitted and prepared for a smaller footprint. The simplicity of a repeated data center floor plate can speed the construction of the initial core and shell, with more of the fit-out to be phased separately or even delayed until the data center space is needed.