If your window security needs upgrading, here are some factors to consider:
The glass itself. Thin, single pane glass (aka “sheet” or “float” glass) is our starting point for this discussion. It breaks easily and has little to offer in terms of heat retention or insulation. (I‘ll address environmental considerations in a future blog, but for now we’re looking at security issues.) The thicker the glass, the better. For substantial burglary resistance, laminated glass is far superior, sandwiching glass and plastic. I’ll discuss bullet-resistance toward the end of this blog entry.
Typical window screens are of next to no value when it comes to security against burglary. Most window screens are great for keeping out bugs, but not much else. Ironically, many homeowners fool themselves into believing the screens will make them safer, thus justifying leaving windows open on hot summer nights. Don’t try this at home, or anywhere else, if you can help it. If there’s no reasonable alternative (such as using fans or air conditioning) at least make it noisy to enter through those windows, either with formal alarms or informal noise makers – stacks of bottles that’ll fall over with a crash, for example.
Plastic panes mounted sometime later, after normal window installation, are sometimes useful barriers to ordinary, non-bullet, threats, such as bricks or sticks, but they most likely will block ventilation (unless riddled with holes for this purpose) and tend to get scratched up over time, so they can end up looking funky.
Embedded wire mesh was popular for a time, holding glass together longer, and thus boosting fire resistance. Unfortunately there have been some cases of injury when students’ hands accidentally were thrust through mesh windows, (such as by pushing hard on the window in a locked door) so I’d suggest extreme caution using these anywhere there’s a risk of kids running into them. There are definitely alternatives.
Security film is an interesting option, useful in some circumstances. Government buildings often use this for holding glass together to deflect thrown objects, and businesses often use it to deter intruders. The downside to the product is the cost (at least $10/square foot, installed, last time I checked) and the fact that the glass is still destroyed—it’s just hard to get through. The film is installed on the inside of the glass pane, where it serves to hold the pieces in place.
Sealed windows are a greater deterrent than windows that can be opened, as the only means of forcing entry is to smash the glass. This is noisy and potentially bloody, neither of which appeals to most criminals. The downside is that sealed windows cannot be easily opened for ventilation or emergency egress. Ideally, every room should have at least two egress possibilities, whether these be two doors or one door and one window. While school security often emphasizes access control by limiting entry points, there’s a risk of forgetting that egress is at least as important. We often don’t discover threats in time to block entry. When that happens, we need to be able to flee. For this reason, I recommend that if all classroom windows are sealed, teachers keep hammers in their desks for smashing windows when they have no better options.
Occasionally, windows come on the market that include emergency release levers. With this addition, windows that normally serve merely for light or ventilation can be instantly converted into escape paths. One is pictured at the top of this blog, manufactured by graham windows (http://www.grahamwindows.com/wp-content/uploads/911_emerg.pdf )
Open-able windows do allow ventilation and emergency egress, but at a price of weaker security. Most burglaries occur because windows or doors have been left unlatched or ajar, either by accident or on purpose. In school burglaries it’s not unusual to find latches sabotaged by students intending to return after-hours. In other cases window latches just plain fail, often because frames have warped or deteriorated, leaving the hardware ineffective. In the case of sliding windows, lift and slide protection is the most common requirement lacking. Sliding windows often incorporate too much of a gap above the windows, in the upper tracks. When that’s the case, the window be easily slid upwards and wiggled out of the frame – often while the latch is still engaged. Screws installed in the upper track can create bumps to fill the gap, and dowels in the lower track can keep windows from sliding.
Security bars or steel mesh can be installed outside windows, to great effect, permitting ventilation without compromising security, but at high cost in terms of both dollars and ambiance; unless you’re running a prison, you most likely don’t want your facility to look like one. Painting the mesh or bars a non-contrasting color (i.e. white bars over a white-framed window) may take the edge off the look, and vines growing over the mesh can further enhance the appearance, but ultimately it’s hard to overcome a grim overall flavor. Emergency release bars inside some of these windows can make it possible to still use them for emergency egress, but this raises costs even further.
Alarms can be reasonable options in some cases. Contact alarms along the framing will shriek when the windows are opened. Motion detectors are triggered when anyone enters the room once the alarm has been set. More sophisticated devices can send alerts to alarm companies, school security or anyone with a smart phone. Even better, some can trigger cameras, sending live footage along with the alerts.
Extreme screens are an excellent, relatively new option worth considering–at least the type produced by Crimsafe (www.crimsafe.com ), if you can afford them. These involve interwoven steel fibers that stand up to extraordinary abuse, including kicks, steel pipes and hurricanes. If you must have open windows this may be your best option for maintaining solid security, customized to meet your needs as either conventional screens
or in a roll-down model.
At the most extreme end of the window security spectrum, if bullet-resistance is required, there are at least two options: multi-layered, conventional “bullet-proof” glass, or chemically altered glass as discussed shortly. The conventional version involves layering glass with plastic or other materials. For an excellent, lengthy explanation of the physics of bullet-resistance, check out the blog at http://matterchatter.wordpress.com/2012/04/29/the-difference-between-normal-and-bulletproof-glass/
An intriguing, more recent approach to bullet-resistance employs nano-technology to actually alter the composition of the glass itself to resist bullets and hurricanes. (www.cbondsystems.com )