Data centers need space and support

Structural requirements as they relate to floor and ceiling loading, mechanical and electrical equipment space needs, and pathway issues for structured cable distribution, are sometimes not considered in programming. For example, Computer Room Air-Conditioning units (CRAC), UPS, and Power Distribution Units (PDU) are large, and more importantly, very heavy pieces of equipment. When you add to this the server and network cabinets, racks, cable tray, and structured cable systems, the floor and ceiling support requirements may have major impacts on your selection for the location of your data center. In addition, vertical space requirements, either with a raised floor design or not, will make or break the viability of a space for data center use.

Understanding simple points can be crucial to a functional space, such as the height requirements for your equipment cabinets and, in the case of overhead distribution, the added height of the cable tray and its clearance needs. These systems can be in excess of eight feet alone, and when the potential rack chimneys, ducting, power distribution, and lighting are taken into consideration, the floor-to-floor requirements may exceed 14 feet. If you don't have the luxury of a new facility and are required to fit all these systems into an existing space that is not designed to support the requirements of a data center, this can be challenging, to say the least.

Case in point

A new medical center complex in the northeastern United States experienced this very issue. Although the hospital, Central Utility Plant (CUP), and Medical Office Building (MOB) were new, as part of the site acquisition, one of the many existing structures that were to remain and be reused was selected to house the data center. Unfortunately the decision to add a new Tier III, 1,600-square-foot data center to the project did not come until substantial design was completed, and the opportunity to locate it in the hospital structure was not available. The only option was the second floor of the two-story, 35-year-old aforementioned building with a 13-½ foot floor-to-floor dimension. Aside from some obvious deficiencies associated with the choice of this space-such as the requirement to transport all future data center equipment on the existing staff elevators, as there were no freight elevators in the facility, and structural penetration challenges associated with the era and design of this building-the true infrastructure issues were yet to be discovered.

As the data center space planning process began, the designers started asking questions, such as, “What is the structural capacity of the floor?” The initial answer was, “I don't know, and why?” This was not a comforting situation to be in, as the floor loading for a Tier III data center of this size is substantial. In this case, the calculated floor load was approximately 200 pounds per square foot. After structural review, it was determined that the floor would not support the weight of the planned equipment, so structural reinforcement was required for the floor area supporting the data center. Fortunately, the building was being completely gutted, so the cost associated with this effort was not as significant had this not been the case.

Next, attention was turned to the ceiling, which in this case was the roof of the two-story building. Because of the location of this facility, the roof was designed to support a certain snow load; after the calculations were run, the maximum additional load allowed on the roof structure was only five pounds per square foot. Again, the load calculations were run for ceiling supported systems, including air ducts, electrical bussway, cable tray, and lighting, and again it could not support all of the weight. Once again, the structural engineer was called upon to remedy the situation.