Mike Holmes, marketing manager, Nexans looks at how picking the right cabling can make or break a smart building

Smart Building networks have a number of extremely specific requirements, including the need for flexibility, the ability to scale up (or down) easily, PoE (Power over Ethernet) or PODL (Power over Data Lines) capacity and support for Internet of Things and Cloud applications. We’re also seeing previously separate building technology and management systems migrating to Ethernet-based systems and 'All over IP'. This is has a marked effect on the choice of structured cabling and network devices.

Smart Building networks need to support a wide range of devices and applications, from communications and telephony to facility management systems, security and access control, IoT devices and Wireless Access Points. To keep up with increasing demands, and changes that occur throughout a building’s functional lifetime, flexibility is key. Smart Building networks have to keep up with demand that is going to keep expanding inevitably in coming years, the introduction of new applications and devices, and the constantly changing use of building spaces.

Traditionally, buildings were equipped with a vertical cabling backbone, rising through the building and branching off wherever cabling for a floor converged. From there, it would run to individual devices. However, if the designated use of a space in a building changed, recabling could involve tearing down walls or adding ports. So a new approach was developed, using common pathways and consolidation points on different floors. This offers considerably more freedom in developing solutions, but still requires designers to adhere to fixed routes. The introduction of wireless access points combined with fixed access as well as PoE has made designing, configuring, and reconfiguring networks much easier and more suitable to Smart Buildings.

No ‘one size fits all’ solution

Today, there is some discussion about which kind of cabling is ‘best’ for Smart Building developments: copper or fibre? However, that’s not an easy question to answer. In fact, the only sensible answer is: it depends.

A number of installers and manufacturers have been making a case for building LANs that use fibre cabling exclusively. However, most businesses feel the extra capacity this offers isn’t needed and the cost would be too high. So in which cases does fibre makes sense?

Fibre is the best possible solution wherever the highest (symmetrical) speeds and lowest latency are required. However, not every single connection in a building needs the highest possible speed. What's more, Cat. 6A cabling can support speeds up to 10GB/s over 100m distances - definitely sufficient for most in-building applications – whilst also offering PoE. Besides speed and latency, there are other considerations that need to be taken into account. One important reason for utilising fibre is the fact that it can carry data over considerable lengths. Copper’s physical resistance, on the other hand, means its use is limited to shorter lengths. Fibre is ideal for carrying a signal over long distances to a building, and taking it to the different floors or areas within that building. However, on the floors themselves, the bandwidth copper offers is more than adequate for the kind of lengths that commonly need to be bridged.

A fibre-based LAN does away with a number of - costly - elements, such as cabling closets, UPS power, data grounds and floor space. However, copper solutions can make elements such as power outlets for individual devices obsolete.

Fibre is immune to electrical noise and uses fewer electrical components, eliminating a range of potential difficulties related to interference. However, that doesn't mean fibre isn’t affected by other kinds of interference. If light sources aren’t entirely monochromatic, pulse interference may occur. This, in turn, introduces Intersymbol Interference. Furthermore, adequate shielding ensures copper isn’t excessively troubled by interference or crosstalk.

Another consideration is the fact that more and more devices are being added to networks. Ethernet is no longer just used for transporting data, but for networking an ever-growing number of devices. This has a significant effect on power requirements. A new generation of PoE technology allows a three-fold increase in the amount of power transmitted through IP networks (up to 90W), making it possible to connect and power devices such as digital signage and TV monitors. Copper-supported Power over Ethernet (PoE), which allows for extensive powering of devices using data cabling, is extremely important in this respect. Copper cables supporting PoE by RJ45 interface allow a single network cable to be used to provide data connection as well as electric power.

Great care needs to be taken when installing copper as well as fibre, but maintenance and rerouting copper tends to be easier and more cost-effective. Copper also supports perfectly good legacy devices, whereas an All-Fibre LAN would require hardware and equipment upgrades that may boost the costs of fibre adoption.

In short, neither fibre nor copper are ‘better’ - both have their place depending on the specific requirements. To decide which is best for each part of the Smart

Building network, it’s important that you answer a number of questions first…

What type and level of performance do users and devices require - not only right now, but also in the future? Which specific conditions exist in the building or buildings? Which distances need to be bridged? Are there specific requirements with regard to functionality (such as powering devices) or uptime? How flexible does your network need to be to accommodate probable future requirements?

Fibre offers fast speeds and data delivery over very long distances, but it's costly, requires dedicated equipment and is overspecified for many day-to-day uses, now and in the foreseeable future. Copper may have some inherent limitations with regard to distance, but offers sufficiently high speeds for countless practical applications, such as connecting Wireless Access Points. What’s more, copper’s support for PoE can be a major factor in your choice, as it contributes significantly to ease of design and network flexibility.

Best of both worlds

A Fibre To The Office (FTTO) solution can combine the best of both worlds: fibre is laid up from the central switch to a connection point in the office or workplace. Here, a dedicated Ethernet switch ensures intelligent media conversion from copper to fibre. Each FTTO-switch is connected to the central distribution switch and Gigabit Ethernet capability ports with PoE, providing a very practical solution for hospitals or campus sites, where large distances are combined with the need for flexible workplaces.

For years to come, fibre and copper solutions will simply exist side by side, each used in applications where they add the greatest value, at a price point that makes sense for the business case. Saving money by opting for ‘just adequate’ cabling can affect performance, but using the highest performing cable for every inch of the network is costly and pointless. You also need to consider the effort and cost related to maintenance, Moves, Adds and Changes and installation. Taking time to select the correct type and quality for each part of the network really pays off in the long run.