ButterflyMX physical access control system


For as long as we’ve had buildings, we’ve needed ways to control who can access them. This practice is known as physical access control. This is a broad term for any type of system that controls physical access to a space.

In this blog, we define what a physical access control system (PACS) is and outline its components. We’ll also highlight examples of it. After reading, you’ll have a better understanding of PACS. Additionally, you’ll know how to choose the best one for your properties.

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What is a physical access control system?

A physical access control system is a solution that uses a physical barrier to control who can enter a building, room, or space. So, a physical access control system (PACS) is any system that prevents unauthorized people from entering while providing a way for authorized people to easily bypass the barrier.

Controlling physical access ensures that people and assets in a building are safe. At all kinds of properties — multifamily, commercial, gated communities, and more — you can install a PACS to prevent theft, destruction of property, and break-ins. Also, a PACS may provide a way for a property’s visitors to request access.


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What are the components of physical access control?

PACS offer more than physical barriers alone. They consist of several components that operate together to prevent unauthorized property access without hindering access for authorized people.

The 5 main components of a PACS are:

  1. Physical access barriers
  2. Identifying credentials
  3. Readers
  4. Control panel
  5. Server


Physical access control intercom at a gated community.


1. Physical access barriers

To control physical access to a building, you need a barrier. And there are two main types of barriers: physical barriers and authority barriers.


Physical barriers

Physical barriers are exactly what they sound like – turnstiles, gates, and locked doors. To clarify, they’re literal barriers meant to keep unauthorized people out. In order to get past a physical barrier, users must have a device like a key, fob, or PIN code.

Physical barriers may work in combination with authority barriers to block people from entering your building without permission.


Authority barriers

Authority barriers are the people who check the credentials of anyone seeking access. An authority barrier could be a security guard, a staff member, or even residents themselves.

In most cases, an authority barrier also requires a physical barrier.


2. Identifying credentials

Identifying credentials tell the system who is trying to gain entry. These credentials come in many forms.

Fobs and key cards are among the most common credentials. However, PIN codes, QR codes, and smartphones among others can also be used as credentials.

Users scan or enter their credentials at your property’s physical barrier in order to gain access.


3. Readers

A reader is the device installed at an entryway where users scan their credentials. The reader “reads” the credential, then sends that data to the system’s control panel to determine if the person is authorized to enter.

If your PACS has visitor management features, it also offers a way for guests without any identifying credentials to request access. Through the reader, they can request access by calling a tenant or staff member.


4. Control panel

The control panel is essentially the brain of the PACS. To put it another way, it’s the component that actually verifies whether an access credential is authentic.

If the credential is valid, the control panel instructs the physical access barrier to unlock or open. However, if it’s not, the control panel won’t unlock the door or gate.


5. Server

The access control server is essentially a storage system that keeps a detailed record of every entry into your property. Conveniently, it also stores user data and each user’s access privileges. You can store information in either an onsite server or in the cloud. Additionally, you’ll want to ensure that your server is well-maintained and up-to-date to maximize security.


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Physical vs. logical access control

Physical access control is the practice of blocking physical access to a building or space. It requires users to have a physical credential, like a key or fob, to gain entry. Although this is occasionally an adequate security measure, it’s not always enough.

This is where logical access control comes in.

Logical access control takes physical access control to the next level: requiring identity authorization to restrict property access.

In other words, logical access control requires you to use something you know to gain entry, like a PIN code or password. In contrast, a system that relies strictly on physical access requires you to use something you have, like a key or fob.

However, some systems require both logical and physical credentials.


Blending logical & physical access control

Rather than relying on just the physical component, many high-security PACS use a multi-factor authentication method to prevent entry using a stolen key or fob.

Modern high-tech PACS will combine physical barriers and identifying credentials to ensure each person who enters your property is authorized.

For example, the District of Columbia police department reports that most intruders give up after 60 seconds of an attempted break-in. So, if your system has logical access controls in place, your chances of intruders following through with attempted break-ins falls significantly. With this in mind, you should choose a PACS that employs multi-factor authentication if security is a high priority.


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Types of physical access control systems

Physical access control has existed for as long as we’ve had spaces that need security measures. So, there are many variations on PACS that have evolved over time.

Here are some of the most common types of PACS:

  • Security guards: This is possibly the oldest form of physical access control! Nowadays, security guards often work in tandem with other components of PACS.
  • Lock and keys: As a rudimentary form of physical access control, a simple lock and key system gets the job done but isn’t the most secure solution.
  • Key cards and fobs: Key card and fob systems are one of the most basic types of electronic access control. They’re usually powered by RFID technology. But key cards and fobs can be lost or stolen, and don’t provide a way for visitors to request access.
  • Keypads: A keypad is an access control system that requires tenants to use PIN code credentials to gain access.
  • Intercoms: This is the most well-rounded type of PACS. In fact, intercoms allow you to keep your entryways locked without hindering access for residents or guests. The best intercoms have a camera to enable video calling and take a photo of each entry event.


Resident opens a door with key card physical access control system


The best physical access control system

A good PACS that maximizes both security and convenience is rare. But with a smart video intercom, you’ll ensure the safety of your property while providing a simple way for tenants and their visitors to gain access.

Here’s why a mobile-based video intercom is the best way to control physical access:

  • Smartphone-based property access: Authorized tenants can unlock the door or gate and manage guest access right from their phones — the height of convenience.
  • No need for physical keys: Keys and fobs can be easily lost or stolen. But with a smart video intercom, tenants can gain access with just their phones or a PIN code.
  • Camera for security: A video intercom’s camera maximizes security in multiple ways. First, it allows residents to visually confirm who’s requesting access. Second, it creates a visual audit trail of property entries for staff and tenants to review. And finally, it helps deter would-be criminals or trespassers.


ButterflyMX physical access control

The ButterflyMX smart video intercom is the best PACS for multi-tenant properties. Because it’s powered by a mobile app, your residents can open the door from their phones, send virtual keys to guests, and even send one-time delivery passes to couriers!

What’s more, the intercom runs on the ButterflyMX OS secure cloud-based software. This means you and your residents can remotely unlock the door, view door entries, and manage access.

ButterflyMX provides robust security features, boasts easy wireless installation, and eliminates clunky in-unit hardware. Plus, with over 7,000 five-star reviews and a highly rated mobile app, you’re sure to give yourself and your residents a top-notch access experience.



  • Physical access control is the act of restricting who can access a physical space.
  • A PACS consists of a barrier (like a door or gate), a reader, credentials, a control panel, and a server.
  • Physical access systems maintain security at buildings while providing a way for authorized people to easily gain entry.
  • Credentials for a PACS range from keys and fobs to PIN codes and smartphones.
  • The best physical access system is a video intercom like ButterflyMX.


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Katie Kistler

I’m a real estate fanatic based in Texas who loves discovering and writing about innovations in property technology.