How Does a Revolving Door Save Energy?

The air inside a building is conditioned to ensure a comfortable environment for occupants. In summer, this involves air conditioning systems that cool and dehumidify the hot, humid air. In winter, heating systems warm the cold, dry air. Additionally, ventilation systems operate year-round to maintain air quality. Conditioning air requires energy, and every time air escapes or enters the building, HVAC systems must work harder, consuming more energy.

A revolving door minimizes uncontrolled air exchange between the inside and outside. A swing door, when opened, acts like a burst balloon, allowing conditioned air to rush out freely. In contrast, a revolving door is always closed because its seals remain in constant contact with the door frame. Only the air within the small chamber where a person passes through is exchanged, significantly reducing overall air loss.

How Much Energy Does a Revolving Door Save?

The energy savings from using a revolving door are substantial, especially considering that each passage through the door only takes about three to four seconds. However, the savings are not 88%, even though a revolving door loses eight times less air than a swing door. This is because revolving doors still allow some air leakage compared to a fully closed swing door, slightly reducing their overall energy efficiency.

The actual energy savings depend on various factors, including:

• Weather conditions:
  • Heating is less efficient than cooling, and temperature differences are usually greater in winter than in summer, leading to higher energy savings in winter.
  • Windy days increase air exchange through swing doors, making revolving doors even more beneficial.
• Air movement perception:
  • If you feel a draft when walking through a door, it means conditioned air is escaping, increasing energy loss.

Average Heat Loss Per Swing Door Use:

• 78 Wh (267 BTU) lost per passage
• Equivalent to:
  • 1.3 hours of desk lamp use
  • 4.3 hours of compact fluorescent lamp use
  • 306 feet (~93 meters) of car travel
  • Half a mile (~800 meters) of jogging

Would you like further details on the efficiency calculations or case studies related to energy savings?

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