The earliest revolving door was born in 1881, invented by the German designer H. Bockhacker, who designed the door with the characteristic of "no wind leakage". The revolving door is either three leaves or four leaves, then accompanied by a long arc, the circumference of the arc is exactly equal to the circumference of the blades formed by the angle. So no matter how the leaves rotate, it can keep the room airtight. Because of this, some people believe that the revolving door was originally designed to block the horse from entering the room. However, this claim has now been taken as a joke. Since it effectively blocks outside air from entering the room, it was probably originally designed just to keep the room warm. In the beginning, when this kind of door was installed, the flush door would not be installed. However, as we said earlier, it may not be particularly convenient to enter and exit or others are not quite used to walking through this door, so it once caused a big accident. One day in 1942, a fire broke out in a very popular nightclub in Boston, and 492 people died of smoke inhalation because the revolving door was stuck and there was no swing door on the side. Swing doors have been available on both sides of revolving doors since 1943, and many areas are required by law to have swing doors on the sides of revolving doors. Isn't it strange that you would rather have two swing doors on both sides than give up the revolving door. In fact, the reason is very simple, the revolving door is not at all decorative or chicken ribs, it brings benefits than the harm it causes much greater. Energy saving and emission reduction beyond imagination. First of all, the first point is that it can effectively reduce the building's electricity consumption by blocking the loss of indoor cold or warm air. Many people may think that this is insignificant, but in fact, the electricity savings are amazing. It's hard to find studies on the energy efficiency of revolving doors nowadays, because there is a general consensus that they are energy efficient. One study I found was a 2006 project at MIT, which is a bit old, but it's the most recent study on revolving door energy efficiency. The researchers calculated the air loss from a revolving door in a specific building on their campus and compared it to the airflow from a traditional swing door. The results showed that eight times more air flowed into or out of the building in a single pass through a swing door than through a revolving door. Although the energy consumed to heat or cool this air entering the building varied with the seasons, the researchers still calculated that it saved 80,000 kWh of energy, or 80,000 kWh of electricity, when compared to a revolving door used by 23% of the people who used it (this was the usage rate of revolving doors counted at the time) during the year when everyone applied the revolving door to get in and out. In fact, compared to the electricity used to heat and cool the whole building, this is not much, about 1.5% of the total electricity consumption, but if you convert it into carbon emissions, it can reduce about 14.6 tons of carbon dioxide emissions. If revolving doors were installed in buildings all over the world and people were willing to use them, it could indeed be effective in stopping global warming. Another scholar also calculated that, compared with the flat door, each time the revolving door can be pushed open the energy savings - about 36.54 watt hours. In other words, the energy saved each time the revolving door is opened can power a 60-watt incandescent light bulb for a little more than half an hour, well, once the door is opened can save so much electricity. The energy efficiency of revolving doors is actually a modern concept, in the old days it was more about safety.
