It seems that every engineering firm within the last five years states that they are a data center specialist. More and more firms are coming out claiming they are experts in the design of data centers with very little history and few have experienced “lessons learned.” In fact, there are only a few engineering firms that have a history in data center design with over 10 years of experience or more. Yet, we still see engineering firms win work due to relationships among real estate and engineering sales efforts. People hire people.


Design bridging has been around for several years and is intended to integrate design excellence with local engineering (engineer of record [EOR]). The bridging consultant creates the basis of design (BOD), alternative design comparisons, and schematic design (risers and equipment layouts) and then transfers this design to the local engineer for design development, construction documents, and permit. In this manner, the client receives a design from a true data center specialist while gaining the benefits of having a local engineering firm. In most cases, the design bridging consultant then provides peer review services for the owner, as well as uptime consulting, site observation, and additional on-site services during commissioning. Here is how the process works.


Prior to developing the BOD, the data center design bridging consultant reviews some of the latest designs with the owner and EOR team. These reviews would include design configurations such as distributed redundant system design, block redundant system design, and catcher configurations (4 to make 3 vs. 5 to make 4, etc.). Additionally, since mechanical systems vary from region to region, alternative mechanical systems are annualized. A PUE analysis is often done to identify the preferred system within a given region. Costs are then developed for both electrical and mechanical systems and the final decisions are made by the owner.


After completing the alternative systems comparisons, the bridging consultant reviews the owner’s project requirements (OPR) and develops a detailed BOD that is actually more along the line of preliminary performance specifications. The final configuration is created outlining system sizes and performance.


Upon completing the BOD, the bridging consultant then provides schematic design services, including riser diagrams, electrical room layouts, mechanical room layouts, equipment yard layouts, and computer rack layouts. These documents are then transferred to the EOR for piping sizes and equipment schedules.


Since most data centers require long lead items such as switchgear, generators, and transformers, the bridging consultant will create the long lead bid package and specifications to be submitted to the general contractor. In this process, we are able to ensure the proper purchase of the long lead critical items. In some cases the bridging consultant will also create the UPS specifications.


Since many engineering firms do not understand the sequence of operations and intricacies of a complex data center building automation system (BAS) or DCIM system, the bridging consultant will submit a riser diagram along with detail specifications outlining the sequence of operations.


One of the benefits of design bridging is that the systems are outlined early in the process, and the general contractor can create an early guaranteed maximum price (GMP) package prior to construction documents. The long lead items are competitively bid, and the other systems are priced by subcontractors to achieve the GMP.


As the EOR continues to complete the design development, construction documents and permit documents the bridging consultant provides peer review services throughout the rest of the design phase. In many cases the client will also require uptime certification. Many of the firms that are the EOR are not familiar with the uptime tier requirements, and additional consulting by the bridging consultant will be required.


Since the bridging consultant creates the design perimeters and configurations, they are integral to the commissioning process to validate the criteria originally set out in the BOD.


A design/build contractor was retained by an enterprise client to build a 3,000-sq-ft data center at Tier III. The existing critical load for day one was 80 kW. The client requested a 10% growth rate over 10 years equaling approximately 750 kVA. This requirement led to a design load for the generator at 1.5 MW. As the project started going in this direction the bridging consultant was brought in late, and reviewed the design. The fact of the matter was that the generators wouldn’t even start at such a low load of 80 kW. Additionally, the same held true with the chiller system. The new design consisted of a day one design of two 500 kW generators, and two 250 kVA UPS systems designed at 2N saving the client $1.7M on day one.