Rolling doors are not only annoying, they save energy

While most of us are satisfied with the swing and sliding doors for most of our needs around the house, the revolving door remains popular in a variety of contexts.

It is a misleading contraption that always makes the careless user feel ready to snatch and trap. However, these doors have some advantages that have allowed them to retain their popularity in many public buildings around the world. Let’s dive down to why.

You rotate me right round

A drawing for a “storm-door structure” from Theophilus van Canel’s 1888 patent filing. In the 19th century, Van Canel was deeply aware of the benefits of keeping out the weather. Credit: Patent filing, public domain

The revolving door dates back to the late 19th century, when two major patents were filed. An H. from Germany. Bockhacker filed a patent for a revolving cylindrical door in 1881. Meanwhile, the more well-known Theophilus van Canel was granted a patent in 1888 for a three-partition revolving door with all the major features we are familiar with today.

Both of these inventors were deeply aware of the advantages of such designs. Their revolving doors were intended to allow entry and exit from a building without excessive air exchange. Swing and sliding doors enable air and rain to easily enter a building, unless used in a dual-stage airlock design. By comparison, a revolving door that is sealed at the edges prevents it almost completely. Only a small pocket of air is exchanged as each part of the door rotates. Even better, a properly designed revolving door will not be blown away by the wind, and at the same time allows people to enter and exit a building. These advantages lead to the adoption of revolving doors in many public buildings.

Indeed, due to the low volume of air exchange, revolving doors have become a major feature of many skyscrapers. These tall buildings are referred to as the “chimney effect”. The HVAC system in the building heats up the indoor air, which increases with the increase of this warm air wave. This creates a pressure difference with low pressure at the base of the building. When a swing door is opened at ground level, this results in air congestion. This then in turn forces the heated air to the top of the building. This air is frustrating for residents and bad for efficiency, as fresh air needs to be reheated using more energy. The same effect occurs in the warmer months, on the contrary, because the cool air blows in the opposite direction through the building.

Whether built into a 3- or 4-leaf design, rotating doors create a useful airlock that prevents excess air exchange with the outside world. This allows for greater comfort inside, protects the ground floor from the weather and improves energy efficiency.

The naturally-sealed design of a rolling door prevents this problem. Although the door does not seal along with the regular closed swing door, it does much less air exchange because it works better than a swing door opening and closing repeatedly. Its effect is noticeable even in small buildings. Larger buildings that are under chimney impact, with larger pressure differences, will notice significantly more benefits.

A general study conducted by MIT in 2006 found that the benefits of rolling doors can be profound. It was estimated that using a rotating door in only one building would save 74% of its current annual energy costs for heating, cutting 15 tons of CO2 output.

Some folding doors have segmented designs that allow the doors to be folded on their own. This can be effective for bringing long or large objects through the door or maximizing throughput in the event of an emergency.

Although it highlights an error in the rolling door. To take advantage, the rotating door must be used for the choice of the type of swing. Even in buildings with revolving door entrances, many building codes indicate that swing doors will be present. This is often a wise practice, as rolling doors can be a liability in an emergency, with the risk of being suddenly jammed or overwhelmed in a rush to exit. However, if people use swing doors more than regular rolling doors, it does not save any energy.

It is a common fact that rolling doors often frustrate busy people. There’s a reason they don’t often appear in action films – after all, there’s no way to rush. Manual push-driven types may allow someone to push faster, but at the same time the rate must be mechanically limited to avoid hitting other people transiting through the door. Alternatively, automatic doors may rotate at a constant rate, but those who are not as mobile and fast as others will often have to be relatively slow in order to be accessible. Precautions should also be taken for proper access to wheelchair users and those who use other mobility assistance.

Overall, rotating doors play an important role in our buildings. These can be slow and frustrating, especially when they shut down automatically (looking at you, IKEA), but they can save a lot on our energy bills. It’s also good for the climate, at a time when we need every last bit of skill we can get!

Leave a Reply

Your email address will not be published.