The tallest ever recorded person measured a staggering 2.72m in 1940. Fast Forward 80 years and the tallest recorded person is 2.52m tall. We can all agree that these are both extremely rare cases of exceptionally tall people. According to the Office of National Statistics, the average height of the average male and female person (in 2018) was 1.75m and 1.61m respectively. Then why is there such a huge demand for extremely tall revolving and associated swing pass doors? It can’t be to supply a “demand” in extremely tall people. In my opinion, it is simply a question of aesthetics and the requirement for a grand and unforgettable entrance.
It is said that the main entrance doors are the first and last things you see and remember when entering or leaving a building. However, if the large, tall doors don’t function properly, what would you remember then? The design and aesthetics or how you struggled to get in and out the building?
Here are the four main aspects to consider to ensure that a tall door functions as intended:
When exceeding a manufacturer’s standard, maximum dimensions, the amount of work required to be able to offer a specification is huge. Firstly, the manufacturer has to see whether it is possible by reconfiguring the design to ensure parts will meet the additional stress and strains of being outside the standard maximum dimensions. They then need to perform desktop studies to ensure the door will work and all safety requirements can still be achieved. It is then meeting with procurement and understanding the outsourcing of increased sized profiles and parts and determining extended lead times for supplying the parts, manufacturing of these doors, transport logistics and installation times. Once all of this has been established, only then will a specification be issued to an architect.
Taking into consideration all of the above with design, invariably, costs will increase markedly. Additional research into whether the system is feasible and safe and additional costs all add up. Along with this, material sourcing costs will increase due to the size as well as manufacturing and labour costs. All in all a larger door becomes a very expensive door. It is also worth considering that you will be limiting yours and your clients’ choice as who to choose for this door, as only a very few manufacturers can accommodate extreme sized doors, so you will be paying a premium cost on this.
Generally, deliveries for revolving and swing pass doors are made via a hi-ab delivery and wheeled into place for installation. With extreme height revolving doors, delivery methods may have to change to a larger articulated lorry (increasing cost again) as well as requiring special instruction for unloading and moving into place. Site areas are often congested, so to allow smooth deliveries road closures may be necessary, as well as obtaining special road licences to park on main roads, especially in urban/metropolitan areas. This all adds up to more logistical planning and, of course, more cost. Specialist spider cranes may also be required to hoist the glass to its installation position as well as more labour personnel to ensure a safe install. Sites often do not provide banksmen, so additional training may be required to personnel to allow for these skills when delivery to site is required.
By far and away the most important factor when considering extreme height doors is safety. When looking at revolving and swing pass doors, we have to ensure that they adhere to BS EN 16005 – Safety at powered doors for pedestrian use. If the doors cannot adhere to this or we, as a company feel it is too unsafe, we would decline to tender a quotation and advise the heights or widths are reduced to a safer level. The safety requirements on a revolving door are numerous and to increase the heights far above the maximum entails utilising laser sensors in certain areas so no contact is made to the user. One of the critical safety requirements is the emergency stopping of a revolving door. When this is engaged the door must stop dead within 5.7° of rotation. To combat this the rotation of an extreme height door will be reduced significantly. This will, in turn, reduce the inertia built up by a rotating door, thus, meaning it will stop dead within the set safety distance. The major drawback with this is that with a much slower rotation, this will mean a significant impact on traffic throughput. If this is applied to, for example, a high end office tower, then users will not be able to utilise these doors properly during peak periods causing potential bottlenecking or users opting to use the pass door(s), defeating the whole purpose of a revolving door and its energy saving properties.
When considering extreme height swing doors, this poses an altogether different problem in that the door can become inherently dangerous to users when wind loads increase. A bigger swing door will mean more surface area for the wind to make contact with it. This is known as the “sail effect”. The same principle applies to sails on a ship – the bigger the sail, the more wind makes contact with it, the faster the ship will propel.
Extreme sized swing doors will also be much heavier. Couple this with high winds and you have a recipe for disaster. Very few automatic door operators will be able to operate the doors and with the weight, the door will be slow moving. When high winds are involved, this can cause the door to move even slower (when going against the wind) or not function properly when the wind is trying to open/close the door faster than it is intended to. Taking all this into consideration, the kinetic energy built up can cause issues for users of these doors as the safety may be compromised and may even strike the user.
In summary, the reasons stated above are why I believe extreme height doors are not truly fit for purpose and why bigger isn’t always better. Associated with the above reasons, additional items such as servicing costs, cleaning and maintenance and repair costs all become more expensive with these types of doors, as specialist parts are required to ensure they can actually be manufactured, let alone work.
If there is a desire to specify an extremely high door please use extreme caution and take all the above points into consideration. Alternatively contact me and I will be happy to discuss alternative products and carefully considered designs, which may assist with yours and your clients’ needs. In the words of Steve Jobs “Design is not just what it looks like or what it feels like. Design is how it works”.
If it doesn’t work properly is it good design?
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