|
The
windows you choose can have a dramatic affect on your home's overall
appearance.
|
|
Windows
and Energy
Windows should let light in and keep weather out. That's a tall order,
because glass has almost no insulative value and is a poor barrier to
radiant energy. So, if you can't control the way energy passes in and
out through your windows, you won't be comfortable in your home. While
some people augment compensate for inadequate windows by using their heating
and cooling systems, this doesn't produce true comfort, and means spending
more on utilities.
Cold Climate Design
By design, cold climate windows should help keep heat in a building. U-value
is the energy term used to describe a unit's ability to prevent heat loss
through the glazing or glass, sash, or frame. Choosing a unit with the
wrong U-value is like wearing a swimsuit in a blizzard: There's not much
keeping the heat in. Heat can also escape through windows as radiant energy.
Warm is attracted to cool, so radiant energy from people and objects is
drawn out through the glass. You can actually feel this happen when the
air temperature is warm, but you feel chilly whenever you approach a window.
Another way to increase efficiency is
to use insulated glass units (IGUs), or windows with an air pocket sealed
between two layers of glass. The trapped air insulates much like a layer
of down in a coat. In gas-filled IGUs, manufacturers use exotic gases
like argon or krypton to fill the pocket and achieve lower U-values.
|
Hot
Climate Design
In a hot climate, the goal is to keep heat out. One way heat enters a
building is by conduction, when cool inside air comes in contact with
warm exterior glazing. Again, the cool air draws in the warmth, defeating
the cooling effect indoors. A lower U-value makes this less likely to
happen. Solar heat gain happens when radiant energy from direct or reflected
sunlight enters through the window glass. High-tech prevention is available
in low-e coatings which prevent the passage of radiant energy or solar
heat into the home. An easy, low-tech solution is to minimize the amount
of sun that hits your windows. Shading the windows with vegetation, awnings,
or overhangs such as porches and eaves provides respite from the sun's
burning rays. Another option is to decrease the size and number of windows
on the east and west sides of the building.
Ventilating Windows
Most windows open and close so bring air flow to your home. Operable units
open many different ways. Double hung windows slide up and down, while
sliding units move from side to side. Casement and European-style windows
swing in or out like doors. Hopper and awning units are hinged to tilt
in from the bottom or out from the top. Windows and doors are major architectural
elements, so be sure to choose those that match the design of your home.
For example, a 1920's bungalow looks utterly ridiculous with modern sliders.
Likewise, a 1960's ranch may look silly with the multi-paned double-hung
units commonly found on a colonial.
Material and Design
The material employed for sashes, frames, and doors affects energy efficiency,
durability, aesthetics, and cost. Wood is often used for doors and windows.
It's paintable, stainable, and a good thermal insulator. Unfortunately,
it rots if you don't keep paint on it. Steel and aluminum are strong,
durable materials for windows, but both have fallen out of favor because
of the way they conduct heat and cold. Vinyl is cheap, durable, and relatively
energy efficient. You can't paint it, but it does come in a number of
colors. Fiberglass windows, while expensive, are durable, paintable, and
strong.Wood windows clad or faced in vinyl or aluminum is another option.
The cladding enhances the durability of the window without compromising
the thermal performance and design flexibility of wood.
It is critical to keep design and style
in mind when selecting windows for your home. Windows are a huge investment
and will significantly impact the look, feel, and operation of your home,
so take the time before you buy to select a material, style, and model
that is right for you.
|