Green Networks: A Solution

Summary: A major potential energy savings area not addressed or discussed is Information Transport Systems and Local Area Network (LAN) systems within a building and/or campus.  These systems require space, power systems (primary and secondary), HVAC, and what seems to be endless need for maintenance.

Running a building or campus network is a major cost area of building or campus operation (voice, data, and video). We have learned that we cannot live or work without it.  However most facility personnel treat it as hands off and refer it to the IT guys for “their requirements.” Isn’t it time the tail stopped wagging the dog?

What if you could decrease or eliminate the space requirements, the need for “freezing” HVAC (ever been in a server room?), and mitigate maintenance and vulnerabilities for business continuity and security?  It is time to reel in the energy eating monster and slay it.  Are you interested in reducing total cost of ownership (TCO) by as much as 65 percent and seeing a decrease in power consumption by as much as 50 percent (source: Motorola POL white paper, 2010)?

How Can This Be?

The move to providing greener buildings and attaining LEED certification has made many steps in the right direction and technology has provided the opportunity to achieve that goal.  Likewise technology is one of the most important systems in our buildings (sensors, controls, software, and so on) and one of the largest consumers of power, HVAC, and space (see Figure 1). It is also one of the most vulnerable systems in day-to-day operations and largely misunderstood by most architects, construction companies, and facility management personnel.

Most server rooms are full of routers, switches, panels and miles of patch cables for voice, data, and media that stifle the imagination of most professionals and, quite frankly, scares many of them. Between the noise, cold temperatures, and apparent cable chaos, who can blame them?

Figure 1: Current Technology – A Corporate Server Room

Architects have been restricted in building design by the distance and space needs of the copper-based LAN. They have also been forced to include unwanted extra non-renewable plastics and copper for these traditional LANs in their building designs.
Some engineers have begun to turn to optical fiber instead of copper transport systems; however, they still require the same type of electrical switches as the copper.  There is a better way.

Passive Optical LAN

An alternative LAN solution to copper-based systems is a new system, known as Passive Optical LAN (POL). POL is based on proven Passive Optical Networking (PON) technology currently deployed by leading service providers around the world and provides triple play services to subscribers. It provides enterprises with fiber optic connectivity to any Ethernet end point such as end-user devices, access points, and wireless controllers, application servers, and printers. POL greatly simplifies the enterprise LAN by replacing copper-based cables and devices in the traditional LAN setting with fiber optic equipment.

Not Smoke and Mirrors

The POL network consists of a high- density aggregation device in the main telecommunication room that delivers converged services over a Gigabit Passive Optical Network (GPON) that extends to the desktop or cubicle and terminates at a Work Group Terminal (WGT). The WGT provides 10/100/1000BaseT Ethernet connectivity to desktop equipment such as desktop computers, laptops, voice-over-IP phones, and video phones using regular copper patch cords.

POL uses small passive fiber optic splitters which are placed in enclosures in a building, usually at every floor, although theoretically they could be anywhere or just at the main room. These splitters and their enclosures, typically 2 to 4 cubic feet in size, require no power, produce no heat, and can be installed in electric closets, in their own dedicated closets, or behind access doors in walls or ceilings.

Figure 2: Passive Optical LAN (POL)

The POL system also reduces overall power and cooling requirements, and reduces the need for construction materials that are not environmentally friendly. This allows the architect to deliver a structure and interior with extra advantages to both the customer and to the environment, at a significantly reduced cost.

A Comparison

Take the followING example structure to compare a POL with the traditional copper-based LAN in a building. The example is a theoretical six-story research and office facility built for a hospital or university. In this building, there is one main distribution frame (MDF) communications closet and 12 intermediate closets (two per floor, stacked at each end). The structure is 320 feet by 120 feet, with about 250 feet between north and south IDF closets. There are 2,000 faceplates and 4,000 Ethernet jacks/outlets, about 350 feet from each IDF closet. The building also includes 100 wireless LAN units.


An analysis of cable infrastructure requirements for copper-based traditional LAN and POL shows that the POL needs much less cable. One third to one half as many horizontal distribution cables are needed to provide the same or an even greater number of user work area ports (Ethernet outlets). The fiber optic cables for POL are a fraction of the size of the Category 5, 6, and 6A cables used for copper LAN.

Most of the weight of copper LAN cables is from plastic, and some is from copper. The fiber optic POL cables are mostly incorporated of plastic and some glass. Category 6 cables are about 24 pounds per 1,000 feet, Category 6A cables are about 49 pounds per 1,000 feet, and fiber optic POL cables are less than 12 pounds per 1,000 feet. Assuming that the same number of outlets is required, POL infrastructure uses 2 to 7 pounds less plastic and an additional 2 pounds less copper per outlet than a traditional copper LAN (a reduction of up to 28,000 pounds less plastic and 8,000 pounds less copper).

Construction Costs

The fiber cable infrastructure of POL costs substantially less to install than a copper-based LAN system for the following reasons: 1) There are fewer cables to install, as a traditional LAN setting would require four home-run copper cables to the IDF, whereas only one is fiber cable is required in POL; 2) Fiber cables are less expensive than copper cables; 3) Fiber optic cables are thinner and lighter resulting in further reduction of labor costs; 4) There is less cost for closet fit-outs, cable trays, racks, cabinets, and fire stop penetrations due to the nature of fiber optic cables; and 5) The costs for grounding/bonding backbones are also reduced because fiber optic cable is non-conductive.

Overall construction costs are reduced by the lower material costs and reduced installation labor costs. These calculations are based on typical material, tax, and labor costs in a major city in the Northeast region of the United States. The cost difference is even higher for areas with higher labor costs. In areas with much lower labor costs the cost savings are still present primarily due to lower material costs.

Power Consumption

Due to the elimination of electronic switches in intermediate closets, the designers and architects do not have to worry about the power and cooling requirements for IDF closets. Architects do not have to design the extra power circuits to supply power to power-hungry workgroup switches and can realize tremendous cost savings by eliminating these components with the use of POL. In addition, they do not have to design the cooling requirements for IDF closets, resulting in additional power savings from the reduced HVAC equipment. We have observed that total cooling need for network electronics reduced by more than 50 percent because of these efficiencies in POL network.

Aside from the energy savings due to minimal cooling requirements, POL equipment is inherently energy efficient. The aggregation switch situated in the main telecommunication room can support more than 7,000 Ethernet end points and requires much less power than a comparable traditional distribution switch. Similarly, the workgroup terminals near the faceplates can support four Ethernet end points and consume much less power per Ethernet port than a comparable intermediate workgroup switch. We have observed that POL electronics requires 50 percent less power than a comparable traditional copper-based network.

Many new networks also have devices that use Power over Ethernet (PoE), which is a method of safely delivering small amounts of power directly to a device over the same cable as is used for the Ethernet signals. Typically some Wireless Access Points and some IP telephones are powered in this manner. This method sends low-voltage power over the small diameter 23 or 24 gauge wires in the Category 6 and Category 6A cables, which means that some of the power is lost in the cable itself due to the resistance of copper. With POL, the PoE devices are supplied with power from the WGT, which is physically very close to the telephone or other PoE device.

Consequently, less power is lost in cabling than it would be in a traditional copper-based LAN design. For the example facility, this savings is about 4,600 kilowatt-hours per year, over 2 kilowatt-hours per worker (assuming PoE phones are used).

In the example research facility, the total energy savings are 50 percent less electricity and 50 percent less cooling than a traditional copper LAN. This is a reduction of 140,000 kilowatt hours per year, which is about 70 kilowatt hours per worker. Much of this information is contained in the Motorola POL white paper from 2010, and is available at

Time To Embrace Green Technology

One of the major obstacles and objections comes from network professionals.  Why? Because it goes against everything on which they have trained. They have spent time and resources toward attaining certifications to install and maintain the old technology.  When I come up against their objections I ask them, “Were you reluctant to give up your bag phone for a flip phone when they first came out?”  Or “How long did it take you to get that smart phone you now have?”  Let’s face it, the world of technology changes all the time.  The days of having a freezing network room with power-hungry switches is over.  It’s time to think green, be green,  and be responsible.

James Clifton, MS, CBCP, is the Director of Operations with PearlNet, LLC in Atlanta, GA, and can be reached at

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