The central key - an obsolescent model

Each resident in an apartment building has a central key in their pocket or on the key ring.

It gives access to what everyone in the building needs to access – from the entrance door through to the bicycle basement. The mechanical system behind a central key is a central locking system.

There are still many of these systems in Germany. Current standards in security and convenience can only be achieved to a limited extent with a central key or central locking system these days. There are more attractive solutions: digital locking systems.

Zentralschlüssel – Seniorenwohnheim

Where is a central key used?

Typical uses of a central lock system with a central key are mainly apartment buildings, rented apartment and condominium complexes and different types of residential homes, retirement homes or similar facilities.

The basic principle is always the combination of shared access doors (e.g. the building entrance door) and individual entrances (e.g. the apartment entrance door) in the same building. The facility manager, caretaker or the owner of the residential complex usually also has a central key in addition to the residents. This means that these people can access all shared areas, but not the individual rooms and facilities (e.g. letterboxes, basement sections).


How a central key works

Many individuals in the building need to lock one or more "central" doors, such as entrance doors or basement entrance doors. However, no tenant or owner may lock another apartment entrance door with their key. The technical complexity of a central key within a central locking system lies precisely in its central functions.

Each individual key must be integrated into the pin system in the locking cylinder in all central doors so that it can lock. Each tenant or apartment owner in the property has only one central key for opening or locking both the central doors (gate, house entrance door, fitness area, underground car park, waste room) and their own apartment entrance door, mailbox and basement space.

Advantages of a central key

Zentralschlüssel – Schließplan

The main argument for a central locking system with a central key is the grouping of individual access authorisations. Different groups of people can be formed (e.g. all family members in a residential unit). Each group of persons is issued with a central key that fits the door locks in the authorised access area and for all centrally used doors.

A central locking system with a central key can closely regulate access by a group of external people such as facility managers, cleaning and security personnel to certain areas of the building complex.

A central key has major disadvantages

Trouble starts when a central key is lost within a central locking system. From this point on, security can no longer be guaranteed for the building. Depending on which holder has lost a central key, certain areas are now fully accessible – all shared access points as a minimum. This situation may continue for hours or days because if a central key is lost because the entire central locking system must be replaced.

Acquiring a replacement is generally difficult in the short term and high costs are also involved. Depending on the size of the building and the number of doors, this can quickly add up to a five-figure sum.

Copying a central key is problematic

If patent protection has expired on a central key and key blanks are in circulation, a copy of the key may be made on any high street. This is, of course, illegal, but it is practically impossible to stop. Central keys created in this way are called pirated keys in specialist groups. Nobody knows their exact number, nobody knows who owns them.

Subletting a flat usually means an unauthorised copy of the central key is made: the main tenant takes their central key with them and has an illegal central key made for the sub-tenant. If the sublet ends and the former temporary resident leaves the building permanently taking with them the central key copied illegally, the security of the building is compromised. Over the years, owners, landlords or facility managers will no longer have a precise overview of what central keys actually exist for the building's central locking system or how many of them there are.

Digital locking technology replaces the central key

SimonsVoss Technologies GmbH (Unterföhring) offers flexible digital system solutions for apartment buildings and rented apartment and condominium complexes which ensure security in both new buildings and existing ones and provide users greater convenience. Digital locking cylinders are used instead of mechanical profile cylinders in the doors. The central keys and all other mechanical keys are replaced by modern, electronic access media. Supplied in the form of cards or transponders, these media are suitably programmed for the required doors. They are contactless and open accesses when held briefly in front of a reader. Facility management is able to administer and control the entire digital locking system and all issued locking media easily. If a locking medium is lost or a new access authorisation is issued, administrators can take immediate specific action in response. A new transponder only costs a few euros while deleting the lost medium and programming a new one takes just a few clicks in the LSM management software by SimonsVoss.

Residents continue to have flexible options when a digital SimonsVoss locking system is installed. This means that a neighbour can be granted temporary access to the apartment in order to water flowers, for example. Building management also has a complete overview of all access authorisations for a building in real time thanks to the software: who is allowed to enter particular areas at particular times?

Zentralschlüssel – digitales Schließsystem

No problems with key loss

Zentralschlüssel – Transponder

There is not always enough budget available to digitally upgrade the entire building and all doors. A practical starting point for entering the world of digital locking technology is provided by multi-story residential buildings whose house entrance doors have electric door openers. Such doors can be retrofitted with the SimonsVoss digital SmartRelay 2 key switch. An external service provider, such as a security specialist and SimonsVoss partner or the building’s own in-house technician, can then manage the cost-effective system for the operator. The white surface-mounted housing is attached outside near the door handle. The integrated electronics control the existing electric strike. The opening process is triggered by the holding an individually programmed transponder (card or chip tag) in front of the sensor.

Here, too, the most important thing is: if an apartment owner loses this locking medium, there is no need to replace an expensive central key. The building management or the external service provider will create (programme) a replacement transponder. As soon as the transponder is used for the first time, the access authorisation of the lost transponder automatically expires and cannot be used by anyone anymore. This means security is restored immediately.