If you think an access control system design is all about the card reading technology, you’re mistaken. There’s a lot more to it than just credentials and verification.

If you start out by focusing on locks and readers, it’s highly likely that after a few years the system will be frustrating users and facility managers alike. Almost inevitably, there will be pressure to replace the system sooner than was anticipated, with all the expense, inconvenience, and reputational damage that entails.

When designing a system, don’t just consider not just the electromechanical technology (locks) and credentialing or verification systems, but also the network infrastructure.

The Communications Network

Modern access control systems are about data. Each person permitted to open and pass through a doorway has a unique ID. This is usually encrypted into some form of card or fob, although cellphones are an increasingly common alternative.

When the credential is presented to the reader, it gets checked against a database of those authorized. Only when a valid match is found is the door unlocked.

Viewed this way, it’s clear the communications technology forms the backbone of the access control system. Accordingly, designing a system that will meet both current and future needs (which are very hard to predict) demands a strong focus on the network. Key elements to consider are:

  • Scale – number of buildings and distance apart
  • Number and location of access points
  • Type and quantity of data to be transferred
  • Integration with existing systems
  • The system environment
  • Upgradeability

We will discuss each one of these in greater detail now.


Ethernet is the de facto networking technology standard within a building, with Power over Ethernet (PoE) strongly preferred for the savings in wiring and cabling. However, copper has limits in bandwidth and distance (even extended range copper), so larger buildings will often use fiber optic cabling.

Fiber is the obvious choice for a campus, although installation may require trenching if no conduits exist. An alternative, and one that’s often preferred for remote locks such as those on entrance gates, is to use a wireless system.

Number and location of access points

A man uses his key card to access a secure building.More access points, and probably more users, means more data, requiring additional bandwidth. As mentioned under scale, distance quickly becomes a limitation for copper wire. The further access points are located away from the server, the more critical it will be to use fiber or wireless technology.

Elevators can present a particular challenge if these are to be integrated into the system. Either adopt wireless technology, use the existing CCTV COAX or UTP or determine how to get the wiring to the elevator car. If you use the existing COAX and convert it to Ethernet, you can combine CCTV and access control on the same COAX for transport to the head end.

Growing numbers of facilities are implementing layered zones for access control. For example, an employee might step out of an access-controlled elevator into a lobby where each door is equipped with a card reader. While they increase security, such approaches significantly increase the number of points to control.

Type and quantity of data to be transferred

In addition to the user ID, many systems incorporate audio and video. The latter is especially bandwidth-hungry, so the system must have the capacity to suit. Biometric verification systems also make intensive use of video. While technology like biometrics might appear overkill today, don’t assume it won’t become essential in a few years.

Access control systems are often integrated with CCTV. One difference is that surveillance systems need to store large quantities of video, requiring high-capacity DVRs or similar devices. Therefore, if your access control will be integrated with CCTV, consider total data transmission and storage requirements.

Integration with existing systems

Almost every commercial and industrial building already has some kind of communications network installed. Rather than duplicating this for the access control system, the logical approach is to use what’s already present.

However, before assuming this is feasible, consider the network topology and bandwidth available –where does the network go, and what else is it used for?

Many facilities have building management systems for CCTV, HVAC, and so on. Check if capacity exists on this network and review the standards used by each system. (Some systems use proprietary technology, which makes it very difficult to integrate equipment from different manufacturers.)

The system environment

Temperature extremes, humidity, and vibration can negatively affect the wiring and electronic devices such as card readers. In addition, some facilities may have explosion-proof requirements. Also, note that high voltages around transformers and electrical arcing from welding processes can disrupt signals sent over copper wire or wireless.


You’d like your access control system to last ten years or more, but a lot can change in that time. Buildings are added on to or sometimes sold off. Usage patterns can change with shift working and business growth. Companies merge or get taken over, requiring the integration of disparate systems.

The primary considerations to ensure the flexibility to cope with such changes are hardware capacity and communications standards. Hardware refers to cables and bandwidth and the switches, hubs, routers, and storage devices that channel and store data and video.

The challenge with communications standards is that some equipment makers have proprietary solutions that tend not to “play well” with those from competitors. Thus it’s essential during access control system design to decide whether you want to lock into one or a few related vendors or have the flexibility to use any non-proprietary hardware.

Consider The Network, Not Just The Locks

To meet the growing needs of facility managers, access control systems are becoming increasingly complex. When designing a system, consider not just the electromechanical technology (locks) and credentialing/verification systems but also the network infrastructure.

In many cases, it’s better to use hardware that’s already in place rather than installing new wiring, switches, and related equipment.

ComNet specializes in networking technology and offers a wide range of network products and access control equipment. Our specialists will be happy to explain what’s possible and discuss your options.