Solved! What Is a Smart Lock and How Does It Work?

Q: Our neighbors were recently away on vacation and mentioned after they returned home that they had forgotten to lock the back door when they left. We said we’d have been happy to take care of it for them, but they showed us an app on their phone that they had used to lock the door from the airport. This sounds like the kind of peace of mind I need—exactly what is a smart lock?

A: Your neighbors’ use of their smart lock is one of the best applications of this security tool. Most homeowners and renters have experienced the sinking sensation of wondering whether or not they locked the door while traveling (or just going to the grocery store). A smart lock lets users check an app and reassure themselves that the door is locked—and if it isn’t, to lock it with a few quick taps. There are more applications, however, that make smart locks a great option that enhances home security for many people. What is a smart door lock? It’s a tool that allows users to control when and how their doors lock, who has access to their home and when, and to integrate their door lock into a smart-home system. And adding the best smart lock to your door means you’ll never have to stand out in the cold digging through a bag for a house key again. Learn how a smart lock works to determine if it’s a good option for your home security.

A smart lock is a device that uses Bluetooth and Wi-Fi connectivity to lock or unlock a door without the need for a traditional key.

What is smart-lock technology, and how does a smart lock work? These devices come in several different styles. All provide keyless entry, usually through a keypad, fingerprint, or remote fob, so for those whose hands are often full when returning home, smart locks provide a great convenience. The lock itself connects to the home’s Wi-Fi network so that it can be accessed via a smartphone app or a control panel within the home, and it connects to both phones and key fobs via Bluetooth. When the app sends a command to lock or unlock the door, the smart lock responds by doing so and confirms the action. The same happens when a user manually punches in a code on the keypad or waves the fob or digital key in front of the lock, depending on the style of the lock itself.

A basic smart lock can fit over an existing lock with only a few modifications needed. 

If it’s time to replace the existing locks on the doors, smart locks can be purchased as stand-alone devices to install in the same way as any other type of door lock. A quick setup to connect it to the home’s Wi-Fi network renders it ready to go. However, for residents who are comfortable with the security provided by their current deadbolts, the convenience of a smart lock is still available: Several companies manufacture smart locks that install over the top of existing locksets. These components also work via Wi-Fi and Bluetooth, but their construction encompasses the existing lock levers, and they deploy a mechanism that physically flips the lock when given the appropriate command. No need to replace the entire lockset—just choose a smart lock that is the correct size to work with the existing lock and install. With permission from the landlord, renters can install them over existing locks with just a few screws to enjoy the same benefits as homeowners and integrate the smart lock into one of the best apartment security systems.

Smart locks can usually be accessed via a mobile app to allow remote door locking and unlocking.

While smart locks provide quite a few security benefits, one of the most useful features is the ability to control the lock from a mobile app. In addition to providing peace of mind by allowing residents to check from afar that the door is locked, this feature also permits users to unlock a door without sharing keys or keypad codes to let in a repairman, babysitter, or a kind neighbor who has picked up a package from the front step.

Many smart locks also offer door locking and unlocking using codes, fingerprint scans, or digital keys.

Most smart locks have a lever on the interior side of the lock that can be physically turned to manually lock and unlock the door. But one primary benefit of the smart lock is keyless entry. Smart-lock technology is still evolving, so different methods of keyless entry can be found in different lock styles, and each has its benefits and drawbacks.

Some systems are unlocked using a code typed into a keypad on the lock face. This method permits users to change the code as often as they choose. It can also allow for temporary or short-term codes with limited access periods, so if a housecleaning service needs to get in every Wednesday at 1 p.m., the user can set a unique code for the housecleaners that only works between 1 and 3 p.m. on Wednesdays. This way, trusted people can have access to the home when necessary, but there aren’t extra keys floating around. The homeowner can feel secure that their home can’t be accessed without permission at other times. Keypads also mean the codes can be changed frequently, which can make the home more secure.

Other smart locks use fingerprint-scan technology to allow access to the home. Similar to keypad entry, the fingerprint sensor can record a number of different fingerprints, and the user can set rules, limits, or conditions on when each print will unlock the door. Some concerns have been raised in the past about the sensitivity and longevity of fingerprint sensors, but as technology has improved, they have become quite reliable.

Digital keys can take several forms. The most common digital key is the smartphone that is paired with the lock or connected through Bluetooth or Wi-Fi. Anyone approaching the door with a paired phone in their pocket or bag will automatically trigger the lock to open. Alternatively, a digital key can be a paired key fob that communicates with the lock and opens it once the fob is in close proximity to the door. Sensitivity varies with each device. While some may have signals that are strong enough to connect from inside a bag or deep pocket, others may need to be held up to the lock to function. But either way, digital keys are easier than fumbling in the dark to get the correct key into the lock on a rainy night.

Residents may worry that a power or Wi-Fi outage will lock them out of the house, but that’s not a concern with a smart lock. First, Bluetooth connectivity will still function even when the home has no power or the Wi-Fi is down. Second, most smart locks also have a standard key slot as backup. As smart-lock technology continues to be a focus of research and development, manufacturers will continue to advance the backup systems to protect against lockouts.

A smart lock can monitor who enters and leaves the home to identify potential intruders.

What’s a smart lock going to do to make a home more secure? Keypad locks with specifically assigned codes will track who enters and leaves the home and when they came and went. Most often, the mobile app will notify the homeowner that someone has opened the lock, and the notification will identify the user based on the code that has been entered. The app will also record attempts to open the door and the code that was used, so if someone with a limited-time code tries to enter at an unauthorized time, the homeowner will be aware.

When paired with a doorbell camera, smart locks add even more security. The doorbell will sense the movement at the front entry and trigger video recording (and alert the homeowner to activity). If an unauthorized visitor attempts to enter a code or use a device to try to bypass the smart lock, the combination of the secure smart lock and the video recording will preserve important evidence to present to law enforcement. As most video doorbells also have communication functions, this combination can also allow the homeowner to interact with the visitor and instruct them to leave.

Smart locks often have auto-locking capabilities that lock the door after a set period of time or when the owner leaves the home’s proximity.

Everyone has, at one time or another, forgotten to lock the door in the rush to get out of the house. However, many people with doors that lock automatically have also made a desperate dive to catch the door before it clicks shut when they realize their keys are on the table inside, not in their hand. Smart locks can alleviate both problems. Auto-locking functions on most smart locks can be customized to fasten the lock after the door has been closed for a certain period of time, so if the user forgets to set the lock, the home will be secured. Similarly, some smart locks sense when the paired fob or phone has left a preset proximity and will automatically lock the door at that time. One of the most important steps residents can take to secure their homes is to lock the door every time they leave the house, so smart locks with this feature truly increase the security of the home and protect residents from unintentionally leaving their home vulnerable to intruders. Because the system can be set to wait for a short interval or to sense that the user has left the area before triggering the lock, users are less likely to accidentally be locked out while grabbing the mail or getting a package off the step.

A smart lock can be integrated into a connected smart-home system to further increase home security.

Smart locks can be stand-alone products. Pairing them with a video doorbell gives users much more information about who is using the lock and when. Most smart locks, however, can be integrated into a full smart-home system, which adds convenience and security to the front door area and the whole home. For example, users can set the smart-home system to respond when the smart lock is triggered, so when the resident approaches the front door at night and their fob unlocks the door, lights can turn on outdoors and throughout the house, music can switch on, and the HVAC system can adjust to the settings used when people are at home. The smart-home system can also be paired with the best home security systems and programmed to notify law enforcement or the home security company if someone tries to tamper with the lock.

What are smart locks’ potential downsides? Many people have expressed concerns that smart locks are hackable, or that they might be breached and allow someone to break into the home’s Wi-Fi and access and control the lock. If residents are using best practices to secure their Wi-Fi, including complex passwords that can’t easily be guessed and appropriate firewalls and privacy settings, this kind of tampering isn’t likely. Those who have a smart-home system in place alongside their smart lock are likely to stay on top of these security practices, and may have a more elaborate network security plan in place to protect their various smart-home devices from hackers. As more and more devices become part of automated smart-home processes, this kind of security will be even more critical. Realistically, though, for smart-lock users who are careful about Wi-Fi security, the chance of a hacker making it through the web of passwords and firewalls is much lower than the likelihood that an intruder will find the old-fashioned spare key under a flowerpot.