6 February 1997
Source: Architectural Record, February, 1997

How Do We Wire the Ever-Changing Office?


By Walter Cooper and Kenneth Silver

Walter Cooper is a principal and Kenneth Silver is a senior associate at Flack + Kurtz,
Consulting Engineers, New York City. The firm specializes in consultingfor such
intense users of data as Wall Street brokerages and investment firms.

Alternative approaches to work -- networking,"hoteling," and teaming -- are becoming increasingly important in the American workplace. And these new ways of working are driving changes in office buildings' infrastructure, including wiring for electrical power, telecommunications, and building-controls systems.

On one hand, recent advances in wire and cable technology. coupled with the development of new standards for their use, have made it easier than ever for designers to choose what type of wire or cable to install. In addition, a recent change in the standard that governs commercial wiring has made it possible for architects to meet their clients desire for increased flexibility by using "zoned" wiring systems, which permit some reshuffling of computers within an office plan with minimal rewiring. These advances, however, come with strings attached. Today's more technically advanced wires and cables must be handled with increased care to avoid damage. And, even though the new zoned systems require a great deal of extra planning and investment, they only satisfy clients' desires for more flexible office systems to a very limited extent.

Appropriately accommodating WANs and LANs

Rapid change in wide-area networks (WANs) and the ubiquity, nowadays, of local area networks (LANs) are forcing a basic rethinking of office-building telecommunications-infrastructure design. The term WAN today commonly refers to a collection of cables that carry signals from the building to and from an outside source. Because of the importance of uninterrupted communications, WAN systems typically are configured as a ring containing two points of access and egress from the building. This system design, known as a self-healing ring, prevents network disruption by allowing signals to travel via the secondary entrance if a break occurs somewhere along the cable loop.

Building tenants not only benefit from additional protection from system failure, they get built-in price competition, because this kind of system design is used by rival telephone companies to install networks. These competing telephone companies may be willing to pay for the installation of their own cables and equipment for the opportunity to sell their services to tenants. As a result, building occupants not only have more choice, they can switch companies in case of emergency.

Such communication networks require a physical infrastructure that mirrors their ring configurations. These and other network requirements should be considered from the very earliest stage of the design process. Architects must provide at least two service entries into the building for wire connections. Where network rings are extended from floor to floor, multiple risers are needed, even in buildings with relatively small floorplates. In addition, space must be set aside in which the many possible vendors of WAN services may locate their equipment. Designers must take care to provide enough space in both telecom rooms and service entrance conduit banks for several WAN suppliers to use.

Wiring by zone

Until very recently, wiring standards haven't addressed the dramatically increasing need -- fostered by various teamwork models that businesses are adopting -- for flexibility and portability of network technology within the office itself. That's changed, however, with the 1996 TSB-75 revision of the Electronic Industries Association (EIA) 5681 standard for commercial wiring, which now permits zone wiring. Previously, individual workstations had to be hard-wired -- that is, connected to a telecommunications closet by an uninterrupted length of cable. With this revision, however, workstations can be plugged into multi-user boxes arranged on a grid beneath an access floor. (See drawings below for comparison.) In some workplaces, this offers immense advantages by minimizing rewiring when reconfiguring furniture and equipment.

Diagrams of Alternative Cabling Solutions (36K)

Though zoned wire-delivery systems (bottom drawing) are not for everyone, their chief advantage is that users can move or reconfigure a workstation without changing wiring all the way back to the telecommunications closet, as is required with conventional systems (top drawing).

As with almost any technical advance, however, the wiring-standards revision also carries some disadvantages that may make it inappropriate. These zoned wiring plans work most effectively as underfloor systems; they shouldn't be considered unless a client is willing to pay the higher initial costs associated with access floors. Zoned wiring systems are not well suited for use above ceilings, for example, because zone boxes need to be accessible on a routine basis, and ceiling boxes are deemed too hard to reach. Mounting multi-user boxes to columns or walls is often undesirable because wiring ends up exposed -- lying on floors or dangling from walls after furniture is rearranged.

The proliferation of connection points in a zoned system also magnifies the complexity of system administration. A zoned system can make it more difficult to keep track of changes, and can complicate the task of troubleshooting when problems arise. Also, the addition of break points at the boxes decreases a wiring system's "headroom," or available transmission capacity. This means that zoned systems that are perfectly adequate for current technologies may prove inadequate for new communications devices that demand greater bandwidth or data capacity. If physical furniture reconfigurations are not actually very frequent, it makes economic sense to stick with wiring each device all the way to the closet -- both to avoid the zoned system's greater initial cost and to avoid limiting the usefulness of the cabling system.

Still in the future: "plug-and-play" networks

Wouldn't it be nice to access your computer network from any desk, and have calls to your phone routed automatically to wherever you are? Despite the advent of zoned systems, this coveted dream is not yet a practical reality. Although this portability may be enhanced by wireless communications, it is an unhappy fact that the currently achievable degree of portability is much lower inside the office than outside. Part of this has simply to do with expectations: outside the office, users have gotten used to the limitations of modems, analog phone lines, and cellular  phones, and are much more willing to put up with a variety of glitches that they'd find unacceptable in the office setting.

Unfortunately, even with zoned underfloor systems, moving a computer or a telephone line from one location to another isn't yet a simple matter of taking a plug from one socket and plugging it into another. Office administrators generally do not encourage telecommunications-equipment portability because it increases equipment maintenance. Likewise, LANs cannot accommodate much movement of computer equipment because of limitations in the way networks are structured. Though a single LAN may incorporate a large number of machines, current network technology dictates that the users be subdivided into groups of no more than about 25. Thus, if a terminal is moved outside its subgroup, administration of the system becomes difficult and communication may begin to break down. (The few "portable" systems that do exist are fairly small, and require a large systems-support staff.)

Wireless technologies are not the magic bullet

Another apparently simple solution is wireless technology, with its potential to avoid a wide range of costly hardware. Today's rapidly developing and proliferating wireless technologies are having a much greater impact outside buildings than inside, where their limited data capacity is a significant drawback. Wireless technologies have, however, already demonstrated significant usefulness in building types in which a high need for portability and mobility is coupled with relatively low data demand. In convention centers, for example, wireless systems are appropriate because the space is reconfigured frequently, there is a low device density, and the need for mobility is high.

In typical office environments, wireless communications technologies are unlikely to come into widespread use in the near future. In addition to slow data-transmission rates, there is another, possibly insurmountable obstacle: the available spectrum (radio frequency and infrared) is very limited, and, once it's gone, the system slows down or stops altogether. This "headroom" problem can be worsened by encryption schemes needed to ensure communications security when the signal is airborne. Generally, these encryption technologies reduce a system's throughput and complicate its operation.

Wireless communications confer little advantage in office environments where layout "churn" is infrequent. Since work stations require hard wiring for power and task lighting anyway, freeing them of the communications wire does little to augment flexibility. Ironically, wireless systems actually make internal reconfigurations of space and furniture more burdensome, because a great deal of care must be taken to ensure that the location of furniture and walls doesn't affect system performance. Also, wireless devices need batteries. Currently available batteries must frequently be recharged -- on a wired device.

All these caveats aside, however, there's no question that wireless communications will play some -- perhaps an increasing -- role in future office environments. The mobility wireless can offer workers may, in niche functions, outweigh its disadvantages. Wireless systems will impose certain design constraints that architects need to become familiar with. For example, if antennas are to be concealed in ceilings, designers must be aware of the radio transparency of the materials they specify-- and ceilings must incorporate wire pathways to service those antennas. (The obvious irony is that "wireless" systems actually require quite a bit of wiring!) Specific applications of wireless may call for specific design strategies. For instance, it would make sense to design the core of a million-sq-ft highrise to allow for an antenna system when a wireless system will link facilities-maintenance personnel throughout the building.

Whether or not a given facility uses wireless, the growth in mobile wireless communications systems is now providing architects with an additional challenge: designing accommodations for antennas on the exteriors of buildings. Owners are leasing their exterior real estate in major cities to telephone companies and other providers, who need more antennas to keep up with demand driven by cellular phones and pagers. Architects have already become adept at designing rooftops to accommodate antenna requirements; now they are being asked to add antennas at, say, five or six stories off the ground, or to specify radio-transparent surfaces to disguise antennas in the mechanical floors of highrises.

Where to wend wires

With the standardization of data and telecommunications protocols, there's no longer the proliferation of proprietary cabling that, a decade ago, seemed as if it might strangle us all in heaps of multicolored spaghetti. Although the standardization of telecom cable has not in every case meant that there's a smaller total amount of the stuff, the fact that there are fewer different kinds of cable to worry about -- and that highgrade cable has gotten a lot thinner over the past few years -- means that the volume of cable for each workstation has leveled off. This has changed the equation by which architects select wire-handling solutions.

Access-flooring products have undergone great improvement in quality, as well, providing a much more solid feel than they used to. Also, access-floor tiles have gotten much thinner. This, coupled with thinner wire, has permitted a significant reduction in the depth of access flooring needed. (Just a few years ago, the minimum depth -- slabtop to top of tile -- was between six and eight in.; today, it's easy to get away with a depth of four in.) Moreover, access-floor voids can be used for ventilation as well as cable distribution--a strategy that's been fairly widely implemented in Europe. This may make access-floor systems more attractive in North America. Using underfloor ventilation in conjunction with a separate ceiling-panel radiant heating and cooling system seems especially promising [RECORD, October 1995, pages 70-85].

Access floors remain prohibitively expensive for many facilities, however. And, despite the fact that it's gotten shallower, access flooring presents a range of design problems -- ramps, elevator offsets, slab depression, and so on -- with which architects have become all too familiar.

Other types of underfloor distribution systems, such as cellular floors, have fallen out of general use in new buildings because of the difficulty of maintaining them and the core drilling and concrete work needed to utilize them over time. The in-slab duct systems with which many facilities were equipped in the recent past will remain usable, and it's important to note that the benefits and problems of the new types of cable affect them as well.

Poke-through wire handling has significant limitations, even though it has been popular for its low initial cost. (In poke-through installations, wire is carried from the workstation down through a floor penetration and runs along the ceiling of the floor below.) It is best suited to spaces with low device density -- a large lobby, for example, that might have a single reception desk. It is difficult to move penetrations and patch them. And each hole through the slab weakens it, which is harmful to the building's structural integrity.

Ceiling- and wall-based distribution systems may offer a good compromise between cost and flexibility. A wide variety of ceiling- and wall-based wire management strategies have been worked out that respect the working style of particular clients.

More important, there is room enough in walls and ceilings to deal with the geometrical sensitivity of high-performance cable. Newer forms of high-grade cable are more delicate. For example, the minimum bending radius of copper cable is relatively large, more like that of optical fiber. High-performance cable, however, can't be just draped over ductwork in a ceiling, but must be adequately supported along its entire length. Pathways must incorporate plenty of room for soft bends and they must have multiple access points to allow the cable to be moved around (when necessary) without damage. And neither high-grade copper cable nor optical fiber will tolerate being pulled through long lengths of conduit. To avoid damage, conduit-enclosed distribution systems require pull-boxes at frequent intervals, even in a building core. Pull-boxes aren't only expensive -- they're also big, which means that some care must be taken to provide room for them within the distribution system.

In mapping out cable pathways, designers must, of course, be careful that telecom and power cable are placed in separate conduits and that minimum distances between the two be maintained for data integrity. However, there is also a 3-in. required distance between telecom cable and fluorescent light fixtures. Electrical noise generated by the ballasts of fluorescent lamps may have an effect on the performance of high-speed data systems.

Progress in controls technology

Standardizing building-controls protocols would make life easier for both designers and facilities managers, but progress has been slower and more uneven than the standardization of voice and data electronics. What this means is that the degree to which control systems and devices made by different manufacturers can be integrated isn't yet nearly as high as the degree of compatibility between different data and telecommunications systems and devices. The delay in standardization, caused in part by many building-controls manufacturers' resistance to adopting universal, non-proprietary protocols, is, however, beginning to abate. More and more manufacturers are choosing to use the inexpensive, flexible protocols developed by suppliers of computer-network hardware, software, and services, such as Echelon Corporation. This trend is gradually leading to a de facto standardization of building-controls systems. Echelon's LONworks is widely used, but as yet no company's standards have come to dominate the industry.

Two contrary control trends are muddying our view of the future. On the one hand, building "intelligence" has been shifting away from centralized systems to individual devices. "Smart" light switches, motion detectors, and the like are examples of products that eliminate control functions once operated from a central building-management system. Since such devices don't need a wire to the central system, the multiplication of these independently operating devices should reduce hard-wire costs and complexity. However, such devices sometimes do strange things: a motion detector may switch the lights off on a motionless worker. On the other hand, microchip intelligence can now be readily built into more building products, which means that more products are "wired-in" to the building. "Smart" window glazing, for instance, can change its opacity and reflectivity according to external weather conditions, internal heating and cooling needs, or user desire. Since many of these new devices will need connections to a building-wide control system, the capacity of the control system will have to increase, and wires, contact points, and sensors will actually increase.

The retrofit challenge

Among the benefits of smaller, more standardized cabling systems is that the retrofitting of wire- and cable-distribution systems for older buildings has become generally a great deal easier. Historic preservation or adaptive re-use projects, however, can be just as nightmarish as ever. Such variables as small rooms, masonry partitions, and irreplaceable historic finishes that can't be altered make the job of routing wire enormously complicated. Even if the area to be wired theoretically meets cable-length and connection-point limitations, the kind of over-under-sideways-and-through routing that's needed in many preservation projects sometimes increases those distances unacceptably. Moreover, it is difficult to design in flexibility for future changes.

Buildings with very large floorplates -- ironically often built for layout efficiency -- may face similar problems. To meet wiring-distance maximums, distribution closets may need to be distributed at intervals around the floor, which may make layouts more complex. It is in such difficult circumstances, that wireless systems may offer a solution despite the limitations of the technology.

Near-revolutionary changes are in the offing. They are not telecom related, but are due to the rapidly shrinking electrical-power needs of office machines. Already, many designers are oversizing power systems, anticipating that power-hogging PCs, printers, fax machines, and copiers will continue to burgeon. Instead, power needs are stabilizing and may soon decline as energy-conserving equipment comes into wider use (box, below) and once-separate pieces of equipment (computing, fax, telephony) are combined. Other innovations arising from laptop-computer technology will also reduce energy needs, especially all-important peak loads. Lower-voltage busses, more efficient circuiting, and complementary metal-oxide semiconductor technology (CMOS) are all coming into wider use. Inexpensive flat-screen technology will move rapidly into the desktop market and may make the greatest difference of all, since such screens will require as little as one-eighth the power of today's cathode-ray-tube (CRT) monitors. They will radiate less heat too. Flat screens will also alter office lighting design because they are less affected by glare, and their thinness will allow much greater desktop-design possibilities.


The amount of electricity actually required to run a contemporary office building -- and the amount that such facilities will require in the near future -- is a matter of contentious debate. Today's de facto design standard of about 5 to 6 watts per sq ft is probably twice as high as it needs to be -- and may quickly become as much as four times too high. Over-designing power systems is wasteful in two ways: in the cost of installing and operating the power system itself, and in oversizing the air-conditioning, since cooling assumptions are based on the power designed for the building.

Though owners and designers often assume office power use will increase, office device-density has probably reached its maximum. The amalgamation of various functions into single pieces of equipment is likely to keep numbers stable. Also, under EPA's Energy Star program, manufacturers of computers and other office equipment have been voluntarily decreasing their products' power usage.

So far, these savings (see table), though phenomenal, mostly affect average load. Technical innovations arising out of laptop technology will begin lowering peak loads significantly. Reasonably priced flat screens will be widely used within 10 years. With their much lower power demand and heat generation, we may rapidly reach the point where a conservative power system design will call for an average of only 1.5 watts per sq ft. One-watt-per-sq-ft designs have been achieved in environmentally sensitive, showcase projects like the National Audubon Society headquarters and the Natural Resources Defense Council, both in New York City. These designs require committed clients.

Power-system design has also been affected as once-centralized data-processing machinery has shrunk in size and been dispersed throughout facilities. Dedicated computer rooms often need uninterruptible auxiliary power, augmented air conditioning, and special power-distribution units. Though servers will continue to shrink in size and increase in number, many will still need the power, hvac backup and security features that centralized data centers have always had.




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1. EIA documents are available from:

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See related information on surveillance and bugging devices.

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