Sep 28 2007
Windows are important to the overall design of a home. They come in all sorts of shapes, sizes, and styles in order to give our home the look we want. Windows also provide us with sunlight and beautiful views. But if you are planning on building a green or energy efficient home windows are also essential to the efficiency of the design. Is it possible to have the both of best worlds?
Not every choice you make when building your new green home will be the most efficient one. Sometimes personal preference guides our decisions, but there are ways to align what we want with what an energy efficient home needs.
Windows provide us with two important energy uses: daylighting and passive solar heating. Daylighting is the sunlight that enters the home and reduces the need for electrical lighting. Daylighting can be enhanced with the strategic placement of windows or structural elements that aid in the reflection of sunlight into the home, such as light shelves.
Passive solar heating comes courtesy of radiation from the sun. This heat comes from sunlight that passes through the windows and heats the interior without the use of an active heating system. To learn more about how passive solar heating works, click here.
While passive solar heating and daylighting can be considered positive attributes of windows, when windows are not correctly sized or positioned, these attributes can also be cause for energy loss (the escape of heat and air-conditioning) and significantly affect the temperature of our homes. Considering window placement (orientation to the sun), energy efficient windows, and window treatments are important to increasing a window’s efficiency.
The placement of windows is important because it determines the allowance of solar heat gain from the sun. Putting windows on the south side of your home in northern parts of the country will increase passive solar heat gain in the winter. In the summer, windows will fall in the shade because the sun is higher in the sky and, therefore, is obstructed by the roof or by window overhangs.
Putting large windows on the east or west sides of your home is not the best idea for warmer climates. This is because sunlight will hit these windows at an angle and, therefore, cannot be blocked sufficiently by a window overhang.
Ratings and Efficiency
To further counter the negative energy effects of large windows, choose energy efficient windows with high ratings. One common rating is the U-factor. A low U-factor indicates good insulating ability while a high U-factor indicates poor insulation. Poorly insulated windows can result in the escape of valuable heat and air conditioning.
Awnings, sun shades, and blinds can also increase the efficiency of your windows. They are especially useful in warmer climates where the sun contributes to solar heat gain inside of the home. Blinds can offer added insulation to block unwanted solar heat gain in the summer and retain heat in the winter.
Large windows can be a burden when building a green home, but the beautiful views and ample sunlight they provide are hard to resist. Carefully plan the placement of your windows, choose energy efficient windows, and add window treatments to enhance their efficiency so that your green home can come with a view. To find a window that is right for your climate, refer to Energy Star.