Why Do Many Buildings Have Two Sets of Doors?

Published Categorized as Building Design
Vestibule Entrance Doors

When you walk into grocery stores, hospitals, hotels, shopping malls, and most other buildings, you’ll first approach one set of doors before encountering another prior to entering the building. In the hustle and bustle of everyday life, have you ever stopped and wondered why many buildings have two sets of doors?

Many buildings have two sets of doors to save on energy, keep the building at a constant temperature, maintain cleanliness, as well as for security purposes. Although we often see two sets of doors in buildings, you’ll also find them in houses in cold and hot countries.

In this article, we’ll unpack why buildings have two sets of doors, what the space between the doors is called, the benefits and disadvantages of two sets of doors, and how we’ve seen this space utilized in present times.


A vestibule is a space between the first set of doors you walk through when entering a building and the next set of doors you encounter. This space is also known as an arctic entry.

You can find vestibules in many buildings, as well as homes in very cold or hot areas. These spaces will always be smaller than the main room it leads into and can vary in size and structure. However, vestibules are typically 25 square feet (2.3 square meters) long and can be located at the front, side, or back door.

The Advantages of Two Sets of Doors

There are many things around us that we see but often pay no attention to. Buildings with two sets of doors are one of these things that we accept without genuinely knowing the purpose. However, the structural design of building two sets of doors plays an essential role in saving electricity, adding security, and keeping you comfortable.

Energy Efficiency

One of the most significant benefits of vestibules and why many buildings have them is that they are energy efficient.

A building without two sets of doors is going to encounter terrible temperature fluctuations. Whenever a staff member, customer, client, or patient opens the door, the temperature from outside, whether hot or cold, will rush into the building.

An HVAC system that has to regulate constant temperature fluctuations will have to constantly work hard, which will use up a lot of energy.

The vestibule is an airlock and will prevent temperatures from outside flooding into your building as both doors won’t be open simultaneously. They have the same purpose as revolving doors but without the stress.

With the two-door setup, the temperature inside your building will be consistent, saving you energy and unnecessarily high bills.

A Happy Environment

There is little worse than going out for dinner on a cold night with your partner or friends only to be sitting at a table near the restaurant’s entrance and being blasted with icy air every time the door opens.

Buildings with two sets of doors don’t have these frustrating problems. Whether working or sitting near the vestibule, the heat or cold from outside won’t be able to blast you. By having two sets of doors in your building, you’re guaranteed happier staff and customers.

They Keep the Building Clean

Not only do two sets of doors keep the cold air out and keep the temperature consistent inside the building, but they also keep it clean.

Every time someone opens a door, the dust from outside comes in. If it is a windy day, you can expect to find leaves, sticks, and other debris blowing inside with you.

Thankfully, a vestibule prevents most of the outside debris from entering the building and instead traps it in the small space, making it easy to sweep out without much time or effort.

Vestibules will keep your office, restaurant, hospital, or building looking clean and professional for longer.

A Mudroom

A vestibule can act as a type of mudroom where you can leave or dust off your wet, dirty shoes as well as your coat and umbrella before entering the building.

A vestibule is also a great space to securely hold packages briefly before sanitizing and bringing them into the building.


Vestibules are also essential when it comes to security. Many banks and jewelry shops have two sets of doors that automatically lock if you set the silent alarm off, trapping the thief and protecting the store.

Trapping the thief between these two doors prevents the thief from getting away. It will protect the staff and customers inside the store from any possible violence from the thief. It will also prevent new customers from walking into the store until police arrive, arrest the thief, and take him away.

Hospital Admittance Area

We’ve had to adapt in various ways since the Coronavirus pandemic began in 2019. Using spaces for purposes other than what they were built for, to keep people safe, has become the norm.

In recent months, nurses have used the space between the two sets of doors as an admittance area for patients.

The vestibule is a safe area, out of the wind or rain, where nurses can check patients’ symptoms and information before admitting them into the hospital for surgery or a doctor’s visit. Once the patient has been moved on, nurses can then sanitize the space and allow the next patient in, repeating the process.

The Disadvantages of Two Sets of Doors

Although there aren’t many disadvantages of having two sets of doors in a building, a clear con is that it takes up space that the company could’ve used for a larger office area or other necessary room.

Another con would be the expense of adding a vestibule into an existing building.

Many people consider whether the advantages of two sets of doors are worth losing out on valuable space, but looking at everything we’ve discussed, I think it’s safe to say that it is.

Each situation is unique, and it’s the owner or company’s decision to make, taking in all of their factors.


Many buildings have two sets of doors to be energy efficient, maintain the temperature inside the building, maintain cleanliness, and for extra security.

Often these spaces can be used as a package drop-off spot so that the staff can sanitize them before bringing them inside the building, as well as a hospital admittance area.

The disadvantages of having two sets of doors in your building are that it takes up valuable space and is pricey to add to an existing building.


By Giovanni Valle

Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.

Leave a comment

Your email address will not be published. Required fields are marked *