Doors And Windows - Storm Windows And Window Tips Windows can be one of your home's most attractive features. Windows provide views, daylighting, ventilation, and solar heating in the winter. Unfortunately, they can also account for 10% to 25% of your heating bill. During the summer, sunny windows make your air-conditioner work two to three times harder. If you live in the Sun Belt, look into new solar control spectrally selective windows, which can cut the cooling load by more than half.
If your home has single-pane windows, as almost half of U.S. homes do, consider replacing them. New double-pane windows with high-performance glass (e.g., low-e or spectrally selective) are available on the market. In colder climates, select windows that are gas filled with low-emissivity (low-e) coatings on the glass to reduce heat loss. In warmer climates, select windows with spectrally selective coatings to reduce heat gain. If you are building a new home, you can offset some of the cost of installing more efficient windows because doing so allows you to buy smaller, less expensive heating and cooling equipment.
If you decide not to replace your windows, the simpler, less costly measures listed below can improve the performance of your windows.
Buying New Windows: New windows are long-term investments that have a large impact on your home's energy systems. Today, there are many new window technologies available that are worth considering, especially those with the ENERGY STAR(r) label. Glazing materials now come with a variety of selective coatings and other features; frames are available in aluminum, wood, vinyl, fiberglass, or combinations of these materials. Each type of glazing material and frame has advantages and disadvantages.
Fact:
* An average household spends more than 40% of its annual energy budget on heating and cooling costs. You could reduce those bills by up to 15% with Energy Star(r) windows.
* Cut heating costs in cold regions as much as 39%.
* Reduce cooling costs by as much as 32% in hot regions.
* Reduce fading (low E-coating blocks up to 98% of the ultraviolet radiation).
* Improve your comfort.
* Improve daylight and view.
* Improve resale position.
* Reduce condensation.
Best Features: Recent technological advances resulted in great improvements in the thermal performance of energy efficient windows. In selecting your windows...
* Buy the right window for your region (northern, central, and southern zones).
* Buy a window with an Energy Star(r) label--it's 40% more efficient than the required building code.
* Look for the NFRC label for best performance and comparison shopping.
Save Money: Using less energy will always save you money. Buying energy efficient windows will save you money, brighten your home, and bring other benefits. By weatherizing your windows, there are many quick and inexpensive ways to save energy and money:
* Caulking gaps around the frames.
* Weather-stripping the sashes.
* Adding window shades and coverings.
* Use the power management feature, and your equipment will create less heat, lowering your air-conditioning costs.
* Set the shortest possible time that is acceptable before your computer automatically powers down.
* Turn your computer off at night, on weekends, and when left unused for an extended period. Storm Windows Poor fitting, single-pane windows can lose energy much faster than modern multi-glazed low-e windows. In extreme weather, such a poor performing window may lose energy ten times faster than an equal area of wall. On clear summer days, an unshaded window adds greatly to undesirable solar heat gain. In many homes, heat loss and gain through and around windows accounts for more than 25% of a home's heating and cooling bills.
The best way to improve your home's energy efficiency is to replace old windows with modern, double or triple-glazed, low-e new or replacement windows. Look for Energy Star(r) labeled windows, as the EnergyStar label indicates that these windows are particularly energy efficient and cost effective for your climate. However, for people with tight budgets, a less expensive option is to use storm windows.
Even though storm windows add little to the insulating performance of single-glazed windows (that are in good condition,) field studies have found that they can help to reduce air movement into and out of existing windows, and thus reduce heating and cooling energy bills.
Types of Storm Windows: Storm windows are available for most types of windows. They are made for installation on the interior or exterior of the primary window. They range from the inexpensive plastic sheets or films designed for one heating season, to triple-track glass units with low-e coatings that offer many years of use. Mid-priced storm windows may use glass, plastic panels, or special plastic sheets that have specific optical qualities. Those made of polycarbonate plastic or laminated glass also offer a high degree of "breaking resistance" to storms and intruders too.
No matter what type you choose, the storm window frame must be hung square with the primary window and sealed to the opening. Exterior-mounted storm windows must have "weep holes" at the bottom of the frame to allow any moisture that collects between the primary window and the storm window to drain out. Even though these drainage holes subtract from energy savings, not having them will eventually cause the primary window frame to rot, and possibly make them impossible to operate.
Glass pane types offer better visibility and longer life than plastic pane types, but glass is heavy and fragile. Plastic panels, such as Plexiglas and acrylics are tougher and lighter than glass, but may scratch easily, and some materials may turn yellow over time.
A low "tech" and inexpensive alternative is to install polyethelene plastic sheets or films on the room side of the window. You can find "do-it-yourself" kits in hardware and home improvement stores, which are plastic films that you tape over the window. Using a hair dryer to shrink-wrap the film around the window helps to tighten the film and improve its transparency. Such kits are used once and then removed at the end of the season.
In general, plastics are most economical for people with small budgets or who live in apartments. The primary advantage is to reduce air leakage into and out of the window. While inexpensive and relatively easy to install, they are easy to damage. Also, some plastic films may significantly reduce visibility and degrade over time when exposed to sunlight.
Frames: The material that the frame of a storm window is made of contributes to how well it insulates and how easy it is to maintain. Wood, aluminum, and vinyl are the most common storm window frame materials. There are advantages and disadvantages to all types of frame materials.
Although very strong, light and almost maintenance free, aluminum frames conduct heat very rapidly. Because of this, aluminum makes a very poor insulating material.
Wood frames insulate well, but weather with age and expand and contract according to weather conditions. Wood-frame storm windows installed during the winter may not close easily during the summer, and those installed during the summer may fit loosely in the winter. They can also be quite heavy and thicker than metal frames. This can make storage difficult, reduce the view out the window, and reduce the amount of natural light in the room. Out of most of the choices in storm window frames, wood frames also require the most maintenance. There are, however, aluminum or vinyl clad wood frames that reduce maintenance requirements.
Vinyl frames are usually made of polyvinyl chloride (PVC) with ultraviolet light (UV) stabilizers to keep sunlight from breaking down the material. However, vinyl frames are relatively weak and may expand and warp at high temperatures and crack in extremely low temperatures. Also, if sunlight hits the material for many hours a day, colors other than white will tend to fade over time.
Exterior and Interior Storm Windows: For the most part, interior storm windows offer greater convenience than exterior storm windows. They are easier to install and remove and often need less maintenance because they are not exposed to extreme weathering. Interior storm window designs may also complement interior decor. Since they reduce air infiltration better, they also reduce energy loss more than exterior types.
Interior types inhibit air infiltration the most because they seal airtight to the primary window. This creates a superior dead-air space relative to exterior storm windows, which require weep holes. As mentioned above, exterior storm windows require weep holes to allow any rain that may be driven behind them or water vapor from inside the house that condenses in the space between the primary window and the storm window to run out of the window. If an interior storm window is sealed tightly to the primary window, the insulation value of the window increases by about R-1 for ordinary glass or plastic. If the glazing has low-e properties then the R-value increase could be as much as 2.
Cost and Payback: The payback period (the time it takes for the money from energy savings to pay for the purchase and installation of storm windows) depends on the initial cost of the windows, the climate, and the cost of fuel. Payback for storm windows in most climates can take decades. This may be offset by the increase in room comfort (fewer drafts) and perhaps an increase in house value (most homebuyers will probably prefer modern energy efficient replacement windows.)
If you can afford to install exterior storm windows, you can probably afford modern, energy efficient replacement windows. Replacement windows that have low-e coatings and other energy saving features give a much better payback than storm windows alone. They also add much more to the value of, and comfort in, the house.
In any case, when making a decision on what type of storm window to buy, in addition to the price, you should consider the following factors:
* Convenience: Since storm windows must be periodically cleaned or opened for ventilation, they should be easy to move. Interior storm windows are often the best choice for apartments and houses with more than one floor.
* Appearance: Consider how it will effect the overall look of your dwelling.
* Maintenance: Remember that some types of storm windows require more maintenance than other types. Warm-Climate Window Tips * In the summertime, the sun shining through your windows heats up the room. Windows with spectrally selective coatings on the glass reflect some of the sunlight, keeping your rooms cooler.
* Install white window shades, drapes, or blinds to reflect heat away from the house.
* Close curtains on south- and west-facing windows during the day.
* Install awnings on south- and west-facing windows.
* Apply sun-control or other reflective films on south-facing windows to reduce solar gain. Cold-Climate Window Tips * Double-pane windows with low-e coating on the glass reflect heat back into the room during the winter months.
* Install exterior or interior storm windows; storm windows can reduce your heat loss through the windows by 25% to 50%. Storm windows should have weather-stripping at all moveable joints; be made of strong, durable materials; and have interlocking or overlapping joints. Low-e storm windows save even more energy.
* Repair and weatherize your current storm windows, if necessary.
* Install tight-fitting, insulating window shades on windows that feel drafty after weatherizing.
* Close your curtains and shades at night; open them during the day.
* Keep windows on the south side of your house clean to maximize solar gain. |
