A Guide to Security Revolving Doors

What exactly is a security revolving door and the 4 Ds of Security.

Revolving doors are probably the most utilised type of entrance system on major offices in metropolitan areas. By their very nature they offer the best way on controlling an internal environment with their “always open, always closed” system and will only let in/let out a pocket of air on each revolution. This in turn reduces the stack effect buildings may suffer from with double height atriums and cold air rushing in, when using other types of entrance systems like swing or sliding doors. They also offer good bi-directional travel in and out of the building, especially when using a 4-wing revolving door and will not take as much of a footprint as when creating a lobby system using an internal and external set of doors. This must be taken into consideration when looking at specifying security revolving doors.

So what is a security revolving door? They’re available in a various diameters, heights and finishes but they also come with various security levels associated with them. This brief introduction will hopefully ease the pain and provide simple explanations as to what you might look for when asked to specify these specific types of revolving door.

Many security firms will often refer to the 4 Ds of security: Deter, Detect, Delay and Defend and they can be defined as the following:

·        Deter – the prevention of criminal activity on your building

·        Detect – the detection of any security breaches on your building

·        Delay – the process of slowing down an intrusion or attack on your building

·        Defend – essentially the act of responding to your attackers if the above 3 fail

 

Deter

A traditional revolving door will sit centrally on the front face of the building; half inside the lobby and half outside. What you will notice is that the external compartment is always open to the elements. From a security standpoint, this isn’t ideal. If the door is situated in an area where vandalism and crime are high, then this is all set to be attacked. Similarly, you also need to consider unwanted visitors or use in the open segment during out of hours. So how do we deter this from attack and unwanted scenarios? The simple answer is by allowing for night closing doors, these are an additional set of doors that are mounted onto the exterior frame of the revolving door. At the end of the working day, security or a member of staff will shut and lock these doors closing and locking off the external compartment and creating a totally safe and secure door. The night closing doors can be manually, or even automatically, operated and the whole door will remain safe.

This is generally enough of a deterrence to would-be vandals, but deterrence can be further escalated by allowing for a burglar resistant revolving door. This revolving door would be independently tested to an RC3 rating and will incorporate a variety of additional features that will be discussed when explaining the delay side of things. I say this, because a deterrence is usually a visible sign, symbol or physical barrier. For example an office building with video surveillance coupled with a revolving door with night closing doors will be enough of a deterrence. The burglar resistant revolving door will have more embedded features that are not totally visible but would be very much noticed when someone was trying to physically break into the building.

Having night closing doors would not affect the performance of these revolving doors and would allow good flow through of traffic during use.

 

Detect

The idea of detection, of possible breaches of your building, can simply come in the form of a fully installed burglar alarm. Security is breached, it is detected and the alarm sounds to alert you of this. But how do you extend this sort of detection when using a revolving door? The security revolving door will come with a host of standard features that can be used as a standalone security detection system or combined with other systems if required by the client. These include:

·        Access control to allow entry into the building

·        Anti-tailgating sensors

·        Anti-piggybacking sensors

·        Weight sensors in the compartment of the revolving door

·        Hang sensors in the doors

·        Volumetric cameras

Access Control – it seems simple, but the first form of security detection is only to allow access to authorised personnel. A user will approach the security revolving door, present their card or fob and a visual signal will let that user know if they are, or are not, authorised to enter. The security revolving door will also start to rotate, providing a stimulus for that person to enter the compartment and go through to the main lobby of the building. If the user is not authorised, they will receive a negative signal and no rotation will be initiated.

Anti-tailgating sensors – You will often hear this term when discussing security revolving doors, but what does it mean? Anti-tailgating is the term derived for someone who tries to gain entry to a building by accessing the compartment behind the, already authorised, compartment rotating around. Essentially the revolving door has received only one signal to allow authorisation and entry for one person, but someone is trying to tailgate that signal by jumping in behind. The anti-tailgating sensors detect this and provides the following solution: it will rotate to allow the authorised person through into the building. It will then stop and automatically reverse in the opposite direction to safely eject the unauthorised person out. That unauthorised person will either have to present their own card to gain entry or contact security to gain entry. Either way, the security revolving door has performed its job by letting through an authorised person, detecting a security breach and eliminated the breach by rejecting the user trying to get unauthorised access.

Anti-piggybacking – you will often hear this term mentioned alongside anti-tailgating as they normally go hand-in-hand. This is similar to anti-tailgating, but this is where an unauthorised user will try and jump in to the same compartment being used by an authorised user. Again, this is one authorisation signal, but two users trying to enter the building. So, how does the revolving door sense this is happening? The sensors within the compartment analyse the topography of each compartment being used and if it detects more people than signals then the revolving door will stop and automatically reverse to safely eject BOTH persons, as opposed to anti-tailgating which will allow the authorised user through and reject the unauthorised person.

Weight Sensors – Weight sensors or contact mats can be provided in the matwell of a security revolving door. They can be configured to take a maximum certain weight that should accommodate a compartment when entering the building. Often used in conjunction with anti-tailgating and anti-piggyback sensors if the weight exceeds the maximum levels set, the revolving door will stop and reverse to either reject a tailgater or a piggy-backer to the exterior side of the building and will continue to allow the authorised user through to the lobby when safe. The weight sensors are completely concealed underneath the matting of the revolving door so there is no visual impact on aesthetics.

Hang-sensors – these sensors were developed for the more intuitively minded security breaker! For those trying to avoid the weight, tailgating and piggybacking sensors and trying to gain unauthorised access to a building, some users were trying to take advantage of the small space at the top of a revolving door leaf, occupied by the horsehair, and hang from the top! These sensors detect when someone is hanging from the top of the door leaf and will act exactly the same way as the other sensors and reject the unauthorised user.

Volumetric Cameras – a relatively new, but expensive, type of “sensor”. Essentially this is a camera situated in the ceiling of the revolving door that will monitor each compartment. When an impulse signal is sent to initiate rotation the volumetric camera will create a picture analysing the contents of the compartment to ensure only the authorised user is in the compartment and no-one else. It will also distinguish if someone is being carried to try and blend in as one person. As mentioned earlier, it is the most expensive solution and not widely utilised and the combination of the above all work well together to act as a detection tool to unauthorised users.

It’s extremely important to ascertain your clients’ exact requirements as the detection solutions described above will have a major impact on the entrance system as a whole.

 

Delay

Due to the type of business that will be occupying the building, there may be a time when a direct threat is experienced. So how do we delay this? A direct threat could come in the form of a foreign, but dangerous object being thrown at the revolving door or even single or multiple people trying to access the building all at once.

If a security revolving door is being used, then upgrading this to a burglar resistant revolving door will prove useful. It was briefly mentioned when discussing deterrence as these are not seen by the naked eye, but more embedded within the door system as a whole. The burglar resistant revolving door is independently tested by an external security consultant, for example TŰV, who will perform timed attacks with specific tools and award the revolving door with a security certification, for example RC3 (resistance class 3). These types of doors will employ more robust materials such as reinforced external posts to prevent the night closing doors from being lifted out of place and entry gained. Multiple high security locking is employed to prevent lock picking. However, one of the biggest features is to use anti-bandit glass with reinforced glazing beads. This glass would be used within the drum walls, door leaves and the night closing doors of the revolving door. It is often rated as P5A glass and looks no different to the standard laminated glass used on revolving doors. The benefit of this glass is that it is extremely resistant to attack – manual or physical and protect your staff and building while authorities are called to attend the attack.

The burglar resistant revolving door will also employ the use of a panic or threat control system. This is where a panic button is situated at the reception desk. When an attack is sensed or unauthorised people are trying to gain access, the receptionist will press this button and this will send a signal to the revolving door motor. The self-locking gear box will then automatically lock-down and the revolving door will stop in that position. The force generated by the locked gearbox will mean that the door leaf will break under pressure prior to the door being forcefully rotated round to gain unauthorised entry illustrating how strong, secure and effective this panic lockdown function is.

What functions are available to you and what you can do to deter, detect and delay any sort of attack on your client’s building. You now need to look at other considerations that will influence your final choice of revolving door. These include:

·        Will the lobby area be manned by security staff during working hours?

·        Will there be an additional layer of security within the lobby, for example security gates or are the main entrance doors the only security line?

·        What throughput of traffic is expected during peak flow?

·        Will the entrances be a fire escape route?

·        How will you allow for disabled access?

·        Are visitors expected to use this building?

Taking each in turn we’ll see how each of these additional factors will influence your choice of revolving door.

It is becoming more commonplace for large office building lobbies to be manned by security staff during normal working hours. Security staff, not only, ensure the safety of the building users but are often seen as the first point of contact to help direct visitors to assistance points such as the reception area or other facilities available in the lobby area. With this in mind, it may work to reduce the security level of the doors and allow for a more deterrence focused outlook when the office is closed. You can also allow for a panic lockdown function as a final resort if required as a lot of the functions mentioned earlier, can be tailored to your exact needs. If the area is not manned by security personnel, you may need to consider increasing the level of security by allowing for detection within the entrance system as well as deterrence for out of hours.

Some office designs have an additional layer of comfort with security gates situated within the lobby area, these are normally sited just in front of lift lobby areas that can lead to the main ground floor core of a building. Couple this with a manned lobby area and the security requirements for your revolving door can be almost be brought down to a minimum with just night closing doors required for out of hours use and the panic lockdown function as a back-up. If there are no security lanes then you will need to look at manned areas and whether you need to increase your levels of security to include detection systems within the revolving door.

Traffic flow and throughput of traffic during peak hours is paramount when thinking about revolving doors. Offices generally have the morning, lunchtime and evening rushes, but how do you work out how many people you need to allow for per minute? Calculating capacity of revolving doors is quite simple in that you need to know the total amount of users, take 15% of this figure and work out the flow of people over a 5 minute period. Your client has informed you there are 2000 members of staff working there. If we say n=15% of this figure, we can use the following formula:

n = (2000 x 0.15) / 5 = 60

This formula provides a level of guidance that the revolving doors will need to allow for approximately 60 people per minute with the results of this having  an impact on the quantity and the level of security your revolving doors will have. By their very nature, security revolving doors will have a maximum diameter of 2400mm, this allows only one authorised person in and out at a time, keeping security intact. However, this will impact on flow through of traffic. General revolving doors can go up to a diameter of 5400mm, however you are seriously sacrificing any sort of security with a mass ingress and egress of people at any one time with multiple occupancy per compartment. So how do you know what’s best? You need to look at the overall security strategy and levels within the lobby area. If it’s manned with security lanes, you’re best going with a general revolving door. This allows for good bi-directional traffic flow and security will be kept intact. For example 3 x 2400mm diameter, fully automatic, 4 wing revolving doors will allow for 72 people per minute which satisfies the criteria of 60ppm. It also allows for any future growth the business may have. Conversely if you opted for a security revolving door with access control, anti-tailgating and anti-piggybacking functions you would be looking at a rate of maximum 20ppm. This is based on everyone knowing exactly what is required of them at the entrance and providing there are no rejections. Although 3 of these doors would satisfy the criteria, you would not allow for any future expansion of the business and if there are multiple rejections during the peak time, then bottlenecking would occur at the entrances which will cause further problems.

An alternative to this is to allow for a fully programmable and customisable security revolving door. Very few manufacturers are able to offer a security revolving door which can be free rotating during peak time travel but then switch to a fully secure revolving door during quieter periods. It is worth looking into manufacturers that offer this solution as it can satisfy a lot of requirements without sacrificing on traffic throughput, capacity, security and adhering to BS EN 16005.

Revolving doors and security revolving doors can also form part of the fire strategy for egress of staff members. They will often be fitted with a break out function where upon fire alarm activation, the door leaves are broken out into the direction of escape and create straight line egress for users to escape the building.

Any automatic revolving door manufacturer will have to adhere to the regulation BS EN 16005 Safety at powered doors for pedestrian use. This dictates that a pass door will always have to be allowed for when a revolving door is specified. This includes security revolving doors. To adhere to part M and to ensure disabled users have an unimpeded path into the building it is worth mounting any sort of access control on there for these members of staff to use. It is also worth mounting a video or intercom system to maintain your security levels with a lock release button at reception so any disabled visitors or even deliveries can gain access securely and safely.

If using a security revolving door, the pass door can also serve to allow visitors, but if you would like them to use the security revolving door it may prove useful to schedule in the visit and issue a temporary day-visit pass prior to the appointment date so security is upheld.

Summary

In summary, as architects, specifiers or consultants there are many factors to consider when looking at specifying a security revolving door. It is worth discussing with your client about what they want to achieve in terms of deterring, detecting or delaying attack but also consider what is most important to them: is it the flow of traffic or the security of the building? All these will have a factor on what sort of revolving door you specify. Will it need protecting after hours or will it need protecting all the time depends on, the building type, staff numbers and hours of operation. As an Architectural Consultant, I am here to assist you on any of these questions you may have, be it on revolving doors or any type of automatic door you are looking at for any of your projects.

 

For more information or assistance with any project, please contact enquiries.esuk@faactechnologies.com where we can provide expert guidance and detailed documentation.