Are Leaving Windows Open At Night A Security Risk?

Yes. An open window is just the opportunity that intruders and burglars need to break into your home.

It’s common for people to open windows to keep the home well ventilated.

And it’s just good practice to properly air your house to eliminate domestic pollutants.

After all, the level of indoor air pollutants exceeds outdoor levels.

However, this practice also compromises your safety, especially at night when intruders often strike.

You may also be compelled to leave windows open at night when the weather is cooler and the house gets stuffy from increased heat from the thermostat.

Even if you are in a relatively safe neighbourhood, having open windows increases the risk of break-ins and home invasions.

It’s something you have to keep in mind when you want to open the windows during nighttime.

You must resist the urge to crack open your windows at night no matter how stuffy it gets.

It’s an open invite for intruders and it gives them easy access to your house either through the upstairs room or the front of your house. 

If I leave my window open at night, am I insured?

Not normally.

Most insurance companies demand that in order to have a valid claim on a policy, you need to make sure that your windows are closed and locked any time that the house is unoccupied or that you retire to bed.

Home insurance policies will vary slightly on a case by case basis, so check out the “small print”  in your own policy.

It might just be that your policy demands that your windows are closed.

I mean how onerous is this? 

Imagine that  you are someone who lives in a larger house (or a house with lots of windows) and you have older children who might open the odd window here and there.

What are the chances of them remembering to close the windows and lock it? Yes, those chances are very slim.

And I think that it is a tough ask for an adult to walk around the house every night before bed checking that every window is shut and locked.

I mean much as we would like, I am not sure that we can be that organised all the time.

Here’s hoping that some boffin invents a reasonably priced robot that can help us with tasks like that.

Can I leave my patio door open at night?

See above! 

Leaving a patio door open at night will be treated with the same level or a higher level of intolerance from your insurance company than leaving a window open.

I mean, you might only be leaving an upstairs window open but if you leave a patio door open an intruder doesn’t even need a ladder!

Of course you can leave your patio door open at night if you like the idea of cool air making you more comfortable at night.

But leave your patio door open knowing all of the consequences- that if you suffer a break- in, your home insurance will be invalidated. 

I mean double check the wording on the policy to make sure…

Here are some great tips to keeping cool at night, but avoid using the hacks that involve an open window! 

However, talking about this level of organisation, I want to move onto discussing the need for a reliable “locking up” routine before you go to bed.

How can you secure an open window whilst you are sleeping?

There are two effective ways you can secure your open window at night to minimize the risk of nighttime burglary.

  • Install window stops.

If the lack of ventilation prevents you from enjoying a deep slumber, then by all means, crack a window open, however, it is recommended that you use window stops.

Window stops essentially act as restrictors. When these stops are installed, you can leave the window open but not all the way through because there’s a mechanism that locks the window into place preventing it from opening further. There will be enough gap for air to get in but not big enough for an intruder to slither through.

These window stops come in different forms depending on the type of windows. There’s the sash stop which works with sliding sash windows. Typically, sash windows have two frames that can slide vertically. You can put sash stops on both sides of the frame so that they can slide up or down up to where the stops are.

A similar mechanism works with a casement-type window and it’s called the casement stay. The stay is a metal bar that keeps the window in a specific position so it doesn’t open or close all the way through. Typically, it allows you to open the window at a predetermined position of not more than four inches.

A window opening and closing control device will allow you to leave windows open without compromising safety and security at home

  • Install security grille.

If you have made up your mind that the only way you’re going to get a restful night sleep is when the window is wide open, you have to fit your window with fixed security grilles. This prevents intruders from climbing into your bedroom while you sleep.

Externally fixed grilles are typically used in commercial buildings but they can work in residential homes as well. The grille normally takes the form of an outer steel frame with welded bars. It’s permanent so it’s not advisable to fit an external grille on windows that are possible exit points during an emergency. External grilles also serve as additional protection to your glass windows.

Internally fixed grilles are much more commonly used in homes. They are shaped from flat steel or expanded bars and come in different patterns (e.g. square or diamond). Since the grille is from the inside, even when the glass windows are open or destroyed, the grille serves as the next line of defense. 

What are the pros and cons of sleeping with a window open?

Sleeping at night with a window open clearly has some benefits, but it also comes with risks and undesirable effects.


  • Sleeping with a window open helps you sleep better because of improved airflow and ventilation.  A better sleep quality contributes to improved emotional state, physical health overall well-being.
  • With a window open at night, it keeps the bedroom cool and the body in thermally neutral level. This means that you don’t have to create or shed heat while asleep, which brings you closer to the optimum sleep environment of between 65 and 72 degrees Fahrenheit. 
  • The air quality becomes significantly better with windows open because indoor air pollutants and carbon dioxide are reduced.


  • An open window at night allows burglars and intruders access to your home. They often strike at night when people are asleep. A window is a potential danger zone because it can easily be broken into.
  • Outdoor allergens like pollen and mold spores can easily get in the house causing allergic reactions. This is particularly hard for people who have high sensitivity to allergens.

Is an upstairs window safer than a ground floor window?

A window is one of the most common entry points for burglars and intruders. Between a ground floor window and an upstairs window, burglars will choose the location that’s easier to enter. In this case, it would be the ground floor window.

An upstairs window is relatively safer because it would take more effort for burglars to climb up the house from the outside. However, this does not mean that they wouldn’t try the first, second and third floor windows, especially if they notice that there’s little to no security in place.

Is a ground floor window safer than a patio door?

It may come as a surprise but burglars and intruders favor entering through the ground floor, either through a window or a door.  So it’s a toss-up between a ground floor window and a patio door in terms of which of the two is safer. It would all depend on how it is reinforced by added security like a grille or a stop.

What are the most common entry points for burglars?

Don’t underestimate the ingenuity of burglars, intruders, and people who want to break into your home. They know how to exploit all the entry points and would wait for the right opportunity to strike. 

Anything with unlocked entrance (be it a door or window) is the perfect point of entry for burglars. Here are the locations that you should mark as danger zones and start installing security cameras, alarms, and locks.

  • Front door
  • First-floor windows
  • Back door
  • Garage
  • Basement window
  • Storage areas
  • Second-floor windows

What Should I Lock Up Before I Go To Bed?

Depending on the time of the year or the busyness of the day, before we go to bed most of us like to lock up- make the house secure.

Unlike in our previous section, we do not lock up before we go to bed in order to comply with an insurance policy.

We lock up to keep ourselves and our families safe.

But here is a startling fact- only 17% of burglaries happen at night. The most common time to be burgled is between 12pm and 4pm. 

But even so, we don’t want to tempt fate and leave doors and windows open.

Developing a routine is helpful for something like locking the house up at night because we are tired and probably in a bit of a rush- a combination that can result in us forgetting things.

Developing a habit at times such as this is a must have.

So, what kind of things should we be checking and is there any trick to making it unforgettable and fail safe?

The list at first seems long and onerous and it starts outside.

Task 1: Make sure any outdoor buildings or garages are locked and that any tools are put away in them.

Can you imagine doing this if the rain is lashing down or if you have heavy snow?

if you leave any tools or objects in your yard or garden that someone can then use to gain entry into your house, it will invalidate your home insurance.

Task 2: Make sure that any outside lights that you have are turned on.

Task 3: Lock any doors or windows in the house and remove the keys 

Task 4: Close the curtains in all the rooms.

Task 5: Close all internal doors to prevent the spread of fire.

Task 5: Set the alarm if you have one.

Task 6: Go to bed taking all the keys (including car), cash and other valuables such as laptops and phones up with you. 

Task 7: Fall asleep safe in the knowledge about how secure you home is.