The best smart locks: Security and convenience

What is a smart lock?

In principle, a smart lock is an electromechanical door lock actuator that turns the key in the lock. Another device with a corresponding authorisation code can trigger the actuator remotely. 

Depending on the model, the smart lock can be placed on the existing security cylinder or comes with a new locking cylinder. In a smart home, the smart lock is a practical addition to the smart doorbell with video surveillance. 

When the long-awaited handyman finally rings the doorbell, you can let him into your home after taking a look at the camera view and exchanging a few words with him via the smart door intercom system. Thanks to smart home technology, the house can also be easily monitored while on holiday abroad. 

The smart door lock actuator not only works on the front door, but is also suitable as an electronic access control for basement and side entrance doors, granny flats, holiday homes, guest rooms or the garden door. 

Are smart locks secure?

The electronic door locks are available in various versions with or without an integrated cylinder lock. Since the smart lock only triggers the mechanics of the cylinder lock, the security of the door lock is first of all dependent on the cylinder used. 

This is because a door lock can be drilled out faster than hacked. Furthermore, the length of the possible passwords, the encryption and the transmission paths play an important role when it comes to security.

When it comes to electronic devices, worrying about hackers makes sense. It is therefore advisable to only buy or use smart locks that have been successfully tested for security. 

The purchase price is not always an indication of the quality of the smart door lock. As various tests show, cheaper devices can certainly keep up with high-priced smart locks in terms of quality and security. Access via an app or the internet in particular poses the greatest risk of a hacker attack. The weak point here is almost always passwords that are too weak. 

Door locks that respond to the nearby smartphone via geofencing or Bluetooth are more secure. Smart locks that can be controlled via PIN keyboards, radio remote control or fingerprint sensor do not use the internet and therefore cannot be hacked, but merely opened in the conventional way.

When used correctly and of the appropriate quality, smart locks offer additional security functions. This is because they log every use with the time of day and, depending on the model, can be monitored or operated remotely. 

Smart door locks also offer precise control of the front door from a distance. In the past, lost keys or keys not returned by staff required in the worst case a replacement of the entire locking system. 

With a smart lock, the digital keys can be controlled, deleted and reissued as required, at no additional cost. 

What are the best smart locks?

Stiftung Warentest extensively tested ten smart door locks in its 10/2020 test. Seven of these electronic door lock actuators do not have a lock cylinder. Six were rated as "Good". Only the Nuki Smartlock 2.0 with Nuki Bridge was rated "Satisfactory" due to security concerns when operating it via the internet. 

Three smart locks were supplied with locking cylinders. Of these, the Yale Entr (YA95) passed the test with an overall rating of "Good". The two models with cylinders from competitor Danalock were rated "Unsatisfactory" because they did not meet the usual security standards for door locks. Here we present the top-ranked smart locks in both categories in detail.

eQ-3 Eqiva Bluetooth smart door lock actuator

As the test winner of Stiftung Warentest 10/2020, it received a quality rating of GOOD (2.1). The smart Eqiva door lock from eQ-3 is easy to fit onto the existing lock cylinder due to the clear instructions for use. However, this requires a profile projection of 8 to 15 millimetres. 

It cannot be seen from the outside that a smart lock is in use. The smartphone app for iOS and Android can be used to securely control the door lock actuator via Bluetooth thanks to the encrypted radio communication. The timed locking function automatically locks the door in the evening at the pre-programmed time. 

The app also controls access authorisations. The optional Ekey Uno fingerprint scanner is compatible with this smart door lock actuator, but considerably more expensive than the actual smart door lock. If app control is enough for you, the eQ-3 Eqiva Bluetooth smart door lock actuator is a first-class smart lock at a low price.

Nuki Smartlock 2.0

Joggers or people with their hands full will enjoy the features of the Nuki Smartlock 2.0, which integrates seamlessly into the smart home environment. 

Thanks to its auto-unlock function, the smart door lock actuator recognises the mobile phone in your jacket pocket or the smartwatch on your wrist as soon as its registered owner approaches the front door. This makes it easy to open the door hands-free after shopping. Stiftung Warentest awarded this smart lock the quality rating GOOD (2.2). 

The Smart Lock 2.0 with Nuki Bridge from the same manufacturer, on the other hand, scores one point lower due to security concerns. The successor Nuki Smart Lock 3.0 with integrated WiFi module has been launched in the meantime to replace the previous Bridge. The new version also has an LED indicator that shows when the battery is running low. However, problems occurred with the Smart Lock 3.0 in individual tests with iOS mobile phones.

Yale Entr (YA95)

The Smart Lock Yale Entry was rated the best model with lock cylinder by the testers in many respects. The battery life of the 7.4 V 2600 mAh battery is longer than that of all other models in the test. 

The locking cylinder successfully resists attempts to drill it open and can therefore be described as a security lock. In addition, the Yale Entr performs well in daily use due to its powerful drive, even overtaking the test winner. The operating noise is comparatively low and the radio transmission proves to be stable. 

Only the installation is a little more complicated than with the test winner, because with the Yale Entr the existing cylinder has to be removed first. Another practical feature is the automatic locking mechanism when the door is closed. 

With a quality rating of GOOD (2.2), this smart lock is ideal for anyone looking for a door lock actuator with locking cylinder. The manufacturer also offers optional accessories such as a wireless charger for the battery, matching profile double cylinders, fingerprint reader, PIN keyboard or remote control. 

What is the best type of smart lock for apartment doors?

Generally, all smart locks are suitable for apartment doors. The smart door locks are invisible when mounted only on the inside of the door and controlled via an app. They can be used without explicit permissions. The additional devices required for access with fingerprint or PIN would have to be installed next to the apartment door and thus be visible in the hallway. 

This usually requires the consent of the owners' association in the case of owner-occupied apartments and the consent of the landlord in the case of rental apartments. The low-priced test winner, for example, is a smart lock for the apartment door that is invisible from the outside and therefore suitable.

How does a smart lock work?

The key is permanently in the lock and the smart lock is mounted on top of it. If the mobile phone or another control device triggers the smart lock, the door lock actuator starts up and turns the key in the lock.

What types of smart locks are there?

Almost all smart locks can be conveniently controlled from a mobile phone via an app. Most of them use Bluetooth to connect. Some of the smart door locks require an internet connection instead. 

This allows the smart lock to be controlled at a distance. Electronic door locks with geofencing recognise the smartphone in a defined proximity, even when it is in your pocket, and open the door. This hands-free function uses the location detection of the mobile phone via Bluetooth or the internet. 

Other smart locks use other types of peripherals in addition to the app or, in some cases, only other peripherals. These include radio remote controls, fingerprint readers or PIN code keypads. 

Are smart locks suitable for all doors?

Common house and apartment doors can all be retrofitted with a smart lock. Some manufacturers point out that their smart locks are suitable for fire doors or other special door types. Other manufacturers explicitly advise against it. 

These exceptions must be checked with the respective manufacturer in each individual case before purchase. So far, smart locks do not unlock any deadbolts or bar locks that may have been fitted. The basic requirement is a cylinder lock with an emergency and hazard function. Since the key is permanently inserted on the inside, it must be possible to open the lock from the outside. 

How can I find out if a smart lock will fit on my door?

There is detailed information and data on the manufacturer's website for most smart door lock actuators. Sometimes the instructions for use can also be found online. 

Otherwise, it is advisable to ask the manufacturer or seller before buying. One of the things to check is the possible key alignment, at least if you are dealing with a vertical lock. The smart door lock actuator should be designed to be powerful enough for a multi-point lock and allow for any length of locking movements. For mounting, the projection of the profile cylinder on the inside of the door is very important for many of the devices. If it is too short, the smart lock will not hold. 

What happens when the smart lock's batteries are empty?

Typically, the devices indicate when the battery is running low by means of a warning light. If you forget to replace the batteries in time, you will be left with a locked door. The only thing that helps in this case is to use a normal key. For this reason, every user should always have a conventional key with them or deposit it with friends or neighbours so that it is easily accessible. 

However, most manufacturers state that the batteries should be replaced once a year. So this problem does not occur too often.

Can I also unlock smart locks with a normal key?

Depending on the model, a smart lock can be controlled via the internet or a mobile phone app. If the internet fails, the battery is flat or the mobile phone is lost, the lock can be unlocked normally with a key. The prerequisite for this is that the profile cylinder is fitted with an emergency and hazard function. 

Since the key remains under the lock actuator on the inside after installation, it must be possible to open the lock cylinder from the outside while the key is still inserted on the inside. In the case of a smart lock with app control via the internet, all it takes is a quick call to another family member who can open the electronic door lock remotely.

Can I install smart locks in my rental apartment?

Many smart locks use the lock cylinder already installed in the front door of the rental apartment and are mounted over it on the inside of the door. The door is not damaged in the process. However, these units require a larger profile projection for this purpose. Other smart locks can be mounted using an adhesive plate and then require less profile. 

The door lock actuators can be easily removed when moving out and the landlord gets his original keys back. Tenants are legally permitted to remove the existing lock cylinder and replace it with a smart lock with integrated profile cylinder. 

If you keep the old lock, you can simply reinstall it when the lease ends. Since smart locks are usually considered an improvement to the property, in most cases the landlord will be happy if it remains fitted in the front door.

What does a smart lock cost?

The basic version of the smart door locks costs between 79 and 375 euros. All smart locks can be controlled via an app and Bluetooth or via WiFi with a mobile phone. 

Some have additional accessories included, such as the needed bridge for internet access, a fingerprint reader, an input device for the PIN code or a wireless remote control. With other door locks, these modules can be purchased additionally. For a realistic price comparison, therefore, the accessories included in the scope of delivery must be compared with the total price of another smart lock plus the costs of the optional accessories. If the basic version with app control is enough for you, the test winner, the eQ-3 Eqiva Bluetooth smart door lock actuator, is the most affordable alternative. 

If, on the other hand, you want to use a fingerprint sensor, for example, it is definitely worth taking a second look at the devices on offer. This is because the optional fingerprint reader for the inexpensive door lock actuator costs between 200 and 300 euros extra. In comparison, the optionally available Yale Entr fingerprint reader YAZU is good value for around 119 euros. However, the basic version of the Yale smart lock costs just under 300 euros. 

When buying a smart door lock, everyone should therefore decide for themselves how much equipment and convenience they want and then carefully compare the purchase prices of the matching offers with the desired accessories.

Do I need a locksmith to fit or change the smart lock?

With a little technical skill, you can install most smart locks yourself. The prerequisite is that the existing locking cylinder protrudes a few millimetres on the inside of the door leaf. 

Because then the mounting plate or the electronic door opener can simply be positioned over it and fastened. For this purpose, the key is inserted into the keyhole on the inside of the door, where it remains. It is important that the key is vertical for mounting, or horizontal in some models. In future, the smart door lock actuator will perform the mechanical turning of the key. 

If the key is a non-standard model with a large key head, it may need to be shortened or the local locksmith can make one with a smaller key head. Smart locks with integrated lock cylinder are installed in the same way, but the old lock cylinder must first be replaced with the one supplied. 

Smart locks controlled via the internet are supplied with an additional device, the so-called bridge, which connects the door lock with the home WiFi. Furthermore, some models can be controlled via Amazon Echo, Google Home or another smart home control system.

What do I need to be aware of when buying a smart lock?

First and foremost, you want to know what functions you want in a smart lock. For children, fingerprint access is probably the easiest option. In the tests, however, this took up to 9 seconds, depending on the model, which often overtaxes the patience of younger children. 

Another alternative would be to open the door by PIN. If you want to open the door of your home for the cleaning lady while you are at work, you will have no choice but to use WiFi and internet. Once you know what access control you prefer, you still have to decide if you want to keep the existing profile cylinder if it is the right size or whether you need to buy a new one. 

This further limits your choice. Then it is simply a matter of comparing the prices for the equipment you want, including the necessary accessories. Sometimes it's worth paying a few euros more if the smart lock offers a higher level of security.

Which reputable test magazines have tested smart locks? Has Stiftung Warentest conducted a test?

Stiftung Warentest tested ten smart door locks for their functionality, security and ease of installation and published the detailed test results in October 2020. The specialist magazine "Das Haus" also tested six smart locks in January 2022. 

Moreover, almost every technology magazine has at one time or another covered electronic door openers. These include Connect, PC-Welt, PC-GO, c't and ETM Testmagazin, to name but a few. We generally see the same models and test results, because the test magazines come to similar conclusions and currently mostly recommend the smart locks mentioned above.

Conclusion: Is it worth getting a smart lock?

Like other smart home modules, smart locks provide more convenience in everyday life. Good and reliable smart locks can be installed without much effort for little money.

Whether operating the mobile phone app is actually much easier than using the key is something everyone has to decide for themselves. Lost or misplaced keys at least are a thing of the past. The advantage of smart locks with hands-free door opening is self-evident. Property owners looking to sell their house or apartment will also benefit from the installation of a smart lock. 

Because not only can they set up temporary access codes for viewings with our agents, but it also adds to the visual value of the property.