The energy-efficient window (EEW) has significantly affected interior structural firefighting. The vinyl window, whether new construction or a replacement, offers improved insulation and security than older-style windows, making it desirable to the building owner and the occupant.

Vinyl windows present challenges and dangers for firefighters in fire conditions. The EEW is more durable than wood-frame, old-style windows with single-pane glass. The EEW frame of vinyl or vinyl-clad wood is structurally stronger than the wood frame. EEW glazing typically is a polycarbonate material that can withstand significant impact and retain its structural integrity longer when exposed to fire. Single-pane glass windows could be expected to fail just before or directly after flashover. This is not the case with EEWs. The insulating qualities of the EEW enable the assembly to maintain its integrity in fire conditions.

The impact resistance and durability of the EEW polycarbonate glazing delays removing the glass and slows ventilation and entry efforts. In terms of firefighter safety and survival, the difficulty in opening or removing vinyl windows could have serious implications when the fire structure must be evacuated rapidly.

To overcome the potential hazards of vinyl windows on the fireground, we must know they are present, how they are constructed, and how to operate them. Employing appropriate opening and forcible entry techniques will improve tactical effectiveness and enhance firefighter safety.

The double-hung style of EEWs is most prevalent in residential construction. Other types, such as single-hung, sliding, casement, and fixed windows, may also be found in residential occupancies. During size-up, identify the window type, method of construction, and style; let the operating forces know that EEWs are present. The opening and forcible entry techniques described here are for the double-hung style of window.

Your first inclination may be to use force to overcome the integrity of the EEW. Striking the window with a heavy tool such as a flathead ax or halligan causes the panes and frame assembly to fail immediately. However, the much more durable assembly of EEWs has greater impact resistance. A different approach is needed.

Today, the forcible entry team often must overcome the latest security devices—doors, locks, gates, and so on. Although these devices are strong and more resistant to entry efforts, you often will find at least one security device part that is weaker or more vulnerable than the others. The same principle applies to EEWs: Identifying and attacking the weak point with the proper tool will enable you to maintain forcible entry proficiency. Training with realistic simulators or using actual windows can help you to develop this proficiency.


Recently, our district conducted hands-on training that included forcing vinyl, double-hung windows. The Dutchess Golf and Country Club purchased a vacant temporary housing complex adjacent to its property in Poughkeepsie, New York, and planned to demolish the buildings to make room for an expanded clubhouse. The buildings were made available to the fire department for hands-on training. However, live-fire scenarios could not be included because of the close proximity of other structures. Nevertheless, the structure provided opportunities for hands-on training in a variety of skills, including primary search, team/large area search, ground ladders, FAST operations, and survival techniques. In addition, the structure’s more than 40 vinyl windows became props for improving the skills of forcing the windows, identifying the tools that would be most efficient in various scenarios, and developing procedures for effectively addressing other EEW-related tasks.

Our firefighters participated in training evolutions that allowed us to develop and evaluate procedures for the following three basic scenarios.

Opening and Removal for Rapid Exit

Firefighters must be acquainted with the design features of double-hung style EEWs (photo 1). This type of window is designed so that each sash tips in for easy cleaning, enabling firefighters operating in the interior to open the window for ventilation or rapid exit when conditions necessitate a hasty evacuation. Latches at the top of the sash and hinges at the bottom of the sash hold two moveable sashes in place. Ventilation latches limit the height to which the bottom sash will open (photo 2). To open and remove the sashes using the tilt-in feature, unlock the window, raise the window about two inches, and locate the slide tabs on the top of the sash (photo 3). Slide them toward the center of the window; pull the top of the sash toward you (photo 4). This will tilt the sash into the room. To remove the sash, grasp the sash near the bottom (hinged) edge; push down on one side while lifting the other (photo 5). This will detach the hinge pins from the track. To remove the top sash, lower the sash to the bottom of the opening, and repeat the previous steps. Push out on the screen frame, if present; in less than 20 seconds, the window will be fully opened for ventilation or escape (photo 6).

Check for the presence of ventilation latches. These devices may not be present on all windows or, if present, used by the occupant. To bypass these latches from inside, push and lock them into the sash frame. Using the window’s features to open it does not destroy the window; therefore, you can practice using these features on windows in structures to which you have access, such as the fire station or your home.

(1) Typical replacement-style energy-efficient window (EEW): frame assembly with two moveable sashes. This window has double-pane, polycarbonate glazing, and tilt-in sashes. (Photos 1-6 by Linda Andersen.)


(2) The opening is restricted to about two inches. The restricted opening distance allows air movement while providing security.



This method can be used for nonfire entry, such as a public assistance call or a medical emergency. Firefighters in the proper personal protective equipment can also use it to gain entry during a fire; the firefighter would be able to work in close proximity to the window.

To force the window, remove the screen, if present; using a prying tool, apply pressure against the locking mechanism (photo 7). The latch is held in place by No. 6 screws, which are three-quarters of an inch long. It takes only minimal force to pull the screws from the sash, usually with no failure of the window (photo 8). Now, by sliding the top sash down, you can access the slide latches on the top of each sash and release them from the frame. If the ventilation latch feature is engaged, the window will not open more than two or three inches. To bypass these devices from inside, push and lock them into the sash frame. From the exterior, you can easily overpower them with a sharp downward pull of a hook or a halligan (photo 9). These small parts will fail easily with the application of sufficient force.

Now with access to the top of each sash, lift the bottom sash a couple of inches, slide the release latches, tilt the sash in, then repeat the steps for the top sash (photo 10). The window is almost fully opened (photo 11).


The previous techniques are performed under conditions that pose little or no threat to firefighters working in close proximity, even when using their hands to manipulate locking and other operating devices. Severe fire conditions that necessitate immediate ventilation of the area directly behind the window, however, do not afford firefighters the luxury of working in direct proximity to and direct contact with the window. These conditions dictate that firefighters use the appropriate tools to overpower the locking and operating assemblies. Properly applied brute force is used to attack the weak points and cause them to fail. The glazing has significant resistance to impact. It may be glass but more likely would be a synthetic material with greater impact resistance. The frame is vinyl or wood covered with vinyl and is extremely durable. This assembly can resist traditional ventilation opening methods quite well.

You can force these windows by using the strength of the sash assemblies to apply shearing force to the weaker attachment points. The pivot points at the bottom and the slide latches at the top are the points by which the sash is affixed to the window frame. These points will fail when subjected to sufficient impact, such as that that can be applied with a striking tool (photos 12, 13).

Using a flathead ax, a halligan, or another heavy striking took, strike near the top of the vertical members of the bottom sash with sufficient force to drive the assembly inward. Pull down the top sash, and repeat the striking procedure, driving this sash into the building. Totally removing the sashes maximizes that opening as a ventilation point and results in an unobstructed opening for entry or egress (photo 14). Having the full size of the window opening available allows you to perform the necessary tactic quickly and efficiently. Leaving the opening even partially obstructed could limit ventilation and prohibit you from using that opening as a means of entry or egress.

(3) To open the window fully, unlock the latch and push the ventilation latch back into the sash frame.


(4) Move the slides near the corners at the top of the sash; move them toward the center line. This will release the latches that secure the top of the sash into the frame.


(5) To remove the bottom sash, tilt it in and push down on one side while lifting up on the other side. This removes the hinge pins from the track. Repeat for the top sash.



The lessons learned from this hands-on training may not apply to all the types of EEWs that may be encountered (see “Some Varying Features of Energy Efficient Windows” on this page).

The acquired structure was an invaluable resource. The EEWs present enabled us to develop procedures for EEW operations and to evaluate the effectiveness of various tools and techniques in forcing entry.

  • It is far easier to use the normal operating systems of the window assembly than to try to overpower the window. When operating from the interior, all the operating features are readily available. Walkthroughs of buildings under construction and even a visit to building supply stores are excellent means of becoming familiar with replacement EEWs and newer models as they become available.
  • When forcing the window from the exterior, attack the weak points—the latch, the slides, and the hinge assemblies. Often, defeating the latch is all that is needed to secure an opening large enough to reach in and operate the slides and release the sashes from the tracks. Opening the window to full size can be accomplished with minimal effort and damage.
  • When more severe fire conditions are present, work a greater distance from the window using tools characterized by less finesse and greater brute force. Heavy striking tools are used to overpower the attachment points. We also used the six-foot steel-handled hook with good results. Striking the top horizontal piece of each sash allows direct impact on the attachment points with the result of failure of the weakest point.
  • The most common glazing in EEWs is polycarbonate based. Most of the windows we worked with had standard plate glass that failed readily, but failure of the glass does not ease the restriction of the horizontal sash pieces—the window is not fully open and would not be able to be used for rapid exit under emergency conditions.
  • Some windows appear as if they are double-hung but may be single-hung assemblies in which the top sash is fixed in place and only the lower sash is moveable. Single-hung units present challenges not only in recognizing them but also in creating an opening that is usable.

Information gathering and analysis are essential to safe, effective fireground operations. Note the presence of EEWs in your preincident surveys. Learn to recognize their presence during initial size-up. Evaluate the impact they will have on fire development and behavior, and adapt your tactics as necessary. When fire and rescue incidents necessitate the rapid use of windows to support the current tactics, it is critical that windows be opened quickly and efficiently. n

(6) Push outward on the screen to remove it.


(7) After removing the screen, pry up the bottom sash; the screws will strip from the sash. (Photos 7-11 by author.)


(8) No. 6 screws hold the locking mechanism in place.



Energy-efficient window features may vary from one manufacturer to another and from model to model. Following are variations we noted during our training evolutions in the acquired structure.

  • Tilt-in feature. Not all windows have this feature. In some windows, the sashes are fixed in place.
  • Glazing. Material varied from standard glass to high-impact polycarbonate glazing.

(9) A sharp, downward impact will cause the ventilation latches to fail.


(10) Pulling down both sashes will give you access to the slides that will release the top of the sash from the frame and enable you to tilt them into the structure.


(11) The window is almost fully opened.


(12) The top corner slide latches hold the sashes to the frame. The hinges at the bottom corners allow the sashes to tilt in.


(13) This window’s slide latches have been released and the top tilted.

  • Single-hung style. The upper sash is fixed in place; the bottom sash is moveable.
  • Ventilation latches. Most windows have one latch; some have two latches that limit the distance the window can be opened. Some windows have no ventilation latches.
  • Window mounting. New construction uses a nailing flange to secure the assembly to the structure’s exterior. Replacement-type windows use a frame and sash assembly that is set into the existing window frame after the sashes have been removed. This results in a frame within a frame, which aids in identification.

RICHARD ANDERSEN, a 29-year veteran of the fire service, is the municipal training officer for the Arlington Fire District, a combination department in the Mid-Hudson Valley in New York State. He has a bachelor’s degree in fire service management from Empire State College and is a nationally certified fire service instructor II and an adjunct instructor at the New York State Academy of Fire Science in Montour Falls.

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