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Does Leaving the Door Open Let All the Heat Out?

Open Door

Photo by [winnond]

So we’ve all heard this one before while growing up, “Don’t leave the front door standing open! You’re letting all the heat out!

If you think about it that sounds a little far fetched that all the heat in a house will magically spew forth an open door. So is there really any truth to this, or is it all just a bunch of hub-bub?

Is the Air Really Going Out the Open Door?

As a child it’s hard to imagine that all the heat in your house would magically disperse through an open door. And if it did, surely it wouldn’t happen quickly enough to warrant such an immediate hysterical reaction from someone. When comparing a large 1,800 sqft home for instance to the size of one small doorway, it just doesn’t add up. But there may be more truth to this than you think.

We have to take a closer look into what exactly is happening when a door is opened in a home to find out the truth behind this old saying. To answer this quickly, I would have to say YES! It actually does make a huge difference in your electric bill to leave your front door standing open.

But it isn’t because all the warm air or cold air is rushing out, the problem is with all the air that is rushing in when the door is opened.  What we’re talking about here is air pressure, sort of like the ole “puncturing the cockpit of an airplane” story. But that is another myth to be busted at another time.

To put it simply, the air is not escaping from your home, the problem is with the outside air being sucked inside that changes the temperature and causes your heating or cooling bill to rise.

Studies Done on Heating and Cooling Costs

In 2010 Cambridge University conducted a study on shop owners that left their front doors open during the winter months. Many of these retailers would claim their invisible “air curtain” bug blasters were responsible for keeping the internal air inside their stores. But according to Cambridge engineers these devices actually use more energy than they save.

They said that one shop owner leaving their door open during an average week of winter was equivalent to a 400 mile plane flight, as far as energy usage was concerned.

Now that’s a lot of energy being used up if you ask me.  According to these calculations, just by closing their front door, the electric bill could essentially be cut in half!

MIT also got into the research action of this study in 2006. They found that by being more careful with the front door, they could save 75,000 kilowatt-hours of electricity in just a single campus building.

To dig a little deeper they took a look at revolving doors as well. Apparently revolving doors will retain heat eight times better than swinging doors, so by everyone switching to revolving doors, heating bills could be lowered by 1.5%.

Air Escaping Opened Doors at Private Residences

Of course these studies were all done on businesses and college campuses, so it’s pretty obvious that a private residence will not have quite as dramatic of an effect as these places. But in all actuality it’s quite the same, just on a smaller scale.

So even though we can’t calculate exactly how much of an effect air escaping through open doors will have on your home, it is quite obvious that leaving the doors open will increase the cost of heating and cooling as well as creating drafts within your home.

According to Home Energy magazine, 7% of a home’s refrigerator electricity is spent while window shoppers hold the door open looking for that special snack to suddenly appear. So it’s probably a good idea to keep that door closed as well.

So to sum things up, Yes, leaving your front door, or refrigerator door open will cause a rise in your electric bill. So if you’re into conserving costs during the seasons, use good judgment and keep things sealed up if you’re not going in or out of that door.

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7 thoughts on “Does Leaving the Door Open Let All the Heat Out?
    1. I hear ya Oksana, I like to touch on the things that most often go unthought of. We can really increase out utility costs by leaving doors open, it’s surprising how much electricity it eats up.

  1. That is totally the other way around here in our country. We open doors to let the heat out since it’s hot in here, specially this summer. We only close our doors when we are going to turn on the AC, go to sleep or go outside.

    1. You must have some pretty cool days around there, what country are you living in?

  2. I think that this was heard more from our Parnts and Grandparents that relied on open fireplaces to heat their rooms. if you opened a door the blast of colder air would draw heat out, but I have never seen such a scientific approach done before, Robert, thanks once again for your time, here.

    1. Yah very true Robert, people don’t worry about this sort of thing near as much as they used to. I suppose as technology advances more and more each day, a lot of things are taken for granted. But when that bill comes in, it can be a quick reminder…lol

  3. So my father wasn’t lying growing up when he yelled at us to close the door because we were letting the cold air out?

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