Re: Containerized Data Center
OK, the replies have all been useful in focusing my thoughts.
A. What is the difference between a building and a piece of equipment? I would say the difference would be whether it has occupiable space, which, according to the code is defined as:
“OCCUPIABLE SPACE. A room or enclosed space designed for human occupancy in which individuals congregate for amusement, educational or similar purposes or in which occupants are engaged at labor, and which is equipped with means of egress and light and ventilation facilities meeting the requirements of this code.”
So, a generator, cooling tower or other such piece of equipment has no occupiable space because it has no egress, light or ventilation. It may have an access hatch that can be unbolted, but that is not a code compliant means of egress. It would not usually have permanently installed interior light or ventilation. A worker would need to bring his/her own portable light and ventilation. Likewise a utility vault, like an electric manhole, is not “occupiable” because you have pry open the lid, put your own ladder down, use portable ventilation for a “confined space” and supply your own portable lighting.
This data center pod on the other hand has what look to be legally sized doors at each end and a legal aisle to provide egress. Presumably, it also has permanently installed lighting and ventilation, so that a technician does not need to bring portable or temporary lighting and ventilation in order to access the space and work inside. So, it seems to me that this pod does qualify as having occupiable space, and would therefore be a building, not a piece of equipment.
It looks like it would probably qualify under NEC 645 “Information Technology Equipment Room.” and is probably also designed to meet the requirements of NEC 110.26 (Spaces About Electrical Equipment).
Another way of thinking about this is, what if instead of being fabricated off-site and delivered as a unit, it were instead constructed conventionally on site. Assume the owner proposed to build a steel building 48ft x 8ft. with metal walls, concrete floor, sloping roof, lights, ventilation, and legal egress. Then he plans to install a bunch of data processing equipment inside. I think that would seem less like a piece of equipment and more like a building.
If it is an occupiable building what occupancy would it be?
The suggestion of U occupancy might be right, but it seems to me that the U occupancy is primarily intended for accessory structures that are adjuncts to some other primary structure. A private garage, carport, greenhouse or shed is associated with a house or other building. The primary building contains the sanitation facilities, so the accessory structure does not need them. Aircraft hangers are included only if they are accessory to a one or two family residence (I know someone who lives in a place like that). Or accessory structures include unoccupiable structures such as fences, retaining walls, tanks and towers. The data center might be an accessory building to some adjacent structure, or it might stand on its own as the only structure on the property. The definition of Group U limits it to structures not classified in any specific occupancy, so if it classified as something else, then it would not be a U. What other classification would fit, or if it is not accessory, then what is it?
The list of uses under Business Group B include: Electronic Data Processing (sounds like that) and also Telephone Exchanges, which would be essentially the same thing. One could argue that those are intended to cover buildings that are regularly occupied by staff, but then the staff would presumably have offices, so they would just be office buildings. The fact that data processing and telephone exchanges are separately listed suggests that this category would apply even if there were no office space included. It looks to me like a stand-alone data center pod would be a B occupancy.
It looks to me like it should be classified as Construction Type IIB, non-combustible non-rated. For a type IIB structure, 1 hr rated exterior walls would be required if it were within 10 feet of an adjacent structure, otherwise, non-rated is OK. Presumably it would have a section 904 Alternative Automatic Fire-Extinguishing System, which does not give sprinkler system credits for code exceptions or reductions.
The 60 foot rule for unlimited area buildings doesn’t seem like it would come into play unless the building has 60 feet clear all around (probably doesn’t in this case), and meets several other requirements that probably also don’t apply.
Interestingly, Table 602 has note f. Group R-3, and Group U when used as accessory to Group R-3, shall not be required to have a fire resistance rating when the fire separation distance is 5 feet or more. Which would imply conversely that a Group U otherwise would come under the requirements of the table.
The big question though is: What difference would it make whether or not it is a B or a U or whether it is an occupiable building or an unoccupiable piece of equipment? B I think there are just a few code requirements that would apply to a building.
The fact that it comes with a NRTL certification would seem to imply that a Building Official need not plan check the interior electrical wiring, nor does it even need to meet electrical code, as that is all covered under the NRTL certificate, just as I don’t need to plan check the interior wiring on a computer or other appliance. That is, the data processing racks on the sides of the pod are covered under the listing, not checked to electrical code.
It seems like the doors would have to meet code for exit doors, so, for example, they have to be openable from inside without a key so someone can’t get trapped inside. The outside air ventilation rate would need to meet code.
The question of sanitation is still hanging. Maybe partly depends what plumbing code is adopted. Depends whether it is accessory to an adjacent primary structure. Seems to me if it is the only structure on the property then it needs a restroom. Otherwise, the technician can’t work there very long without violating OSHA regs. (and other unmentionable consequences as well). On the other hand, if it were a generator next to a communication tower and not an occupiable building, the technician would have the same problem but there would be no restroom requirement.
Energy code compliance is another question. Given the huge amount of process load that totally dwarfs all other loads, it would seem a bit silly to try to apply energy code requirements.
